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Fabrication of Bis-Quaternary Ammonium Salt as an Efficient Bactericidal Weapon Against Escherichia coli and Staphylococcus aureus

  • Zhiyong Song
    Zhiyong Song
    State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, PR China
    More by Zhiyong Song
    Orcidhttp://orcid.org/0000-0002-2552-5239
  • , 
  • Huajuan Wang
    Huajuan Wang
    State Key Laboratory of Agricultural Microbiology, College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
    More by Huajuan Wang
  • , 
  • Yang Wu
    Yang Wu
    State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, PR China
    More by Yang Wu
  • , 
  • Jiangjiang Gu
    Jiangjiang Gu
    State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, PR China
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  • , 
  • Shuojun Li
    Shuojun Li
    State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, PR China
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  • , and 
  • Heyou Han*
    Heyou Han
    State Key Laboratory of Agricultural Microbiology, College of Science  and  State Key Laboratory of Agricultural Microbiology, College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
    *E-mail: [email protected]
    More by Heyou Han
    Orcidhttp://orcid.org/0000-0001-9406-0722
Cite this: ACS Omega 2018, 3, 10, 14517–14525
Publication Date (Web):October 31, 2018
https://doi.org/10.1021/acsomega.8b01265

Copyright © 2018 American Chemical Society. This publication is licensed under these Terms of Use.

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Abstract

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Combating bacterial pathogens has become a global concern, especially the emergence of drug-resistant bacteria have made conventional antibiotics lose their efficiency. This grim situation suggests the necessity to explore novel antibacterial agents with favorable safety and strong antibacterial activity. Here, we took the advantage of quaternary ammonium compounds and synthesized a long-chain high-molecular organic bis-quaternary ammonium salt (BQAS) with a broad-spectrum bactericidal activity through a facile one-pot reaction. The bactericidal effect of BQAS was evaluated by two bacterial human pathogens: Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), which are the major cause of diarrheal infections in children and adults. Our experimental results indicate that the bactericidal activity of BQAS is linked to the strong contact between the positively charged quaternary ammonium groups and the bacterial cells, thus leading to a temporary and locally high concentration of reactive oxygen species, which subsequently triggers oxidative stress and membrane damage in the bacteria. This mechanism was further confirmed by several assays, such as the membrane permeabilization assay, fluorescent-based cell live/dead test, scanning electron microscopy, transmission electron microscopy, together with the lactate dehydrogenase release assay, which all indicated that BQAS induced damage to the cytoplasmic membrane and the leakage of intracellular fluid containing essential molecules. The excellent bactericidal activity of BQAS suggests its great application potential as a promising candidate against the rapid emergence of drug-resistant bacterial pathogens.

Introduction

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Over the past decades, infectious diseases caused by bacteria remain one of the largest health problems in the world (1) and afflict millions of people annually (2) and thus have gained extensive concerns. More than 1.3 million deaths of children are reported to be caused by diarrheal illness worldwide every year, (3) indicating the urgent necessity to develop new antibacterial agents with favorable safety and potent antibacterial activity. To this end, a variety of antibacterial materials, such as antibiotics, (4) antimicrobial peptides, (5) cationic polymers, (6) carbon-based nanomaterials, (7−9) small molecular antibacterial agents, (10−13) and metals or metal oxides (14−16) have been widely used in antimicrobial research. Among these traditional methods, the use of antibiotics is the most common and effective approach to treat bacterial infectious diseases. (17) Despite the critical role of antibiotics in decreasing the morbidity and mortality induced by bacterial infections, (18) the global abuse of antibiotics results in the development of more and more bacteria into resistance against most of the traditional antibiotics. (19) The emergence of antibiotic-resistant bacteria poses a new threat to human health, (20−22) further suggesting the vital importance of discovering new antibacterial materials to replace traditional antibiotics. (23,24)
Quaternary ammonium compounds (QACs), which are usually white and crystalline powders and are very soluble or dispersible in water, have a broad spectrum of antimicrobial activity and often display extended biological activity owing to their long-lived residues on treated surfaces. (25) QACs have good antibacterial activity against both Gram-positive and Gram-negative bacteria at medium concentrations and also possess moderate effectiveness against viruses, fungi, and algae. (26,27) Because of the broad-spectrum antimicrobial activity and surfactant properties, QACs, such as benzalkonium chloride, favor hygienic adjuncts in disinfectant cleaners and have been increasingly used in domestic cleaning products over the last decade. (28) Several mechanisms have been suggested to explain the antimicrobial action of QACs, such as the perturbation of cytoplasmic and outer membrane lipid bilayers through the association of the positively charged quaternary nitrogen with the polar head groups of acidic phospholipids, (29) followed by the interaction of the hydrophobic tail with the hydrophobic membrane core. QACs usually contain four organic groups linked to nitrogen, which may be similar or different in chemistry and structure. The organic substituents are alkyl, aryl, or heterocyclic. To achieve a hydrophobic segment compatible with the bilayer of the outer cell wall, at least one of the organic substituents should be a long alkyl chain. (30,31) Previous studies have demonstrated that with an increasing alkyl chain length of an amphiphilic compound, the hydrophobic interaction with the lipid bilayer of the cell wall significantly increases, which in turn enhances the antimicrobial activity of the compound. (32)
In this article, we synthesized a long-chain high-molecular organic bisquaternary ammonium salt (BQAS) with excellent solubility in water by using a simple one-pot method. BQAS was found to possess both a positive charge and a hydrophobic segment, and its bactericidal properties were investigated by evaluating its bactericidal activity against the Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). The results showed that BQAS has a much stronger ability to kill bacteria at low concentrations, and the Gram-positive S. aureus are more sensitive to BQAS than the Gram-negative E. coli. The bactericidal mechanism of BQAS was also proposed, and it had the potential as a new broad-spectrum antibacterial agent for treating infectious diseases.

Results and Discussion

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In this study, a simple one-step method was used to synthesize BQAS with a high yield (90%) and a highly positive surface charge (ζ-potential ca. +30.2 mV). The molecular structure of BQAS was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectra of BQAS (Figure 1A) showed the absorption bands at 3390 cm–1 (O–H stretching), 2924, 2855 cm–1 (C–H stretching), 1468 cm–1 (C–H bending), 1124 cm–1 (C–N stretching), 1072 cm–1 (C–O stretching), and 721 cm–1 (C–H rocking). The FT-IR spectra matched well with the molecular structure of BQAS. The 1H NMR spectrum is shown in Figure 1B, and the peaks at δ5.16 (1-H), δ3.60–4.40 (2-H), δ3.40 (3-H), δ3.50 (4-H), δ1.80 (5-H), δ1.30 (6-H), and δ0.88 (6-H) demonstrated that BQAS was successfully synthesized under the one-step pathway. The molecular characterizations of BQAS were further consolidated by electrospray ionization-mass spectrometry (ESI-MS) (positive ion). The results are shown in Figure S1. Important peaks in these spectra are found at m/z 519.65, 483.60. These ion peaks account for the direct loss of one/two chloride ions from the molecule, leading to the formation of the positively charged ions (M–Cl)+/(M–2Cl)+. These results suggested that BQAS was successfully synthesized.

Figure 1

Figure 1. Characterization of BQAS by FT-IR spectroscopy (A) and 1H NMR (B).

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The antibacterial effect was quantitatively investigated by measuring the growth curves and death rate of bacteria exposed to BQAS. The growth curve was used to study the dynamics of bacterial growth and evaluate the antibacterial properties of BQAS at different concentrations (Figure 2). In Figure 2A,B, an obvious growth delay could be observed with increasing BQAS concentration, indicating that the antibacterial activity of BQAS was dose-dependent. In addition, the growth delay was much more obvious in Figure 2B than in Figure 2A, suggesting that S. aureus is more sensitive to BQAS than E. coli. Apart from growth inhibition, microbicidal activity is an important indicator for antibacterial materials. The colony count assay was carried out to study the bactericidal effect of BQAS. Figure 2C,D showed the typical photographs of the E. coli and S. aureus bacterial colonies after treatment with various concentrations of BQAS. The number of colonies was significantly reduced with an increasing BQAS concentration, indicating that BQAS has excellent bactericidal activity against both Gram-negative E. coli and Gram-positive S. aureus bacteria in a concentration-dependent manner. Meanwhile, we have selected two other strains of Methicillin-resistant S. aureus (1213P46B; 011P6B5A) and E. coli (EIEC 23-6; EAEC 36) to evaluate the minimal inhibitory concentration (MIC) of the BQAS compounds. The MIC results, as shown in Table 1 suggested that BQAS had good antibacterial effect against the Gram-positive and Gram-negative bacteria.

Figure 2

Figure 2. Growth curves of (A) E. coli and (B) S. aureus in LB medium at 30 °C after the bacterial cells (200 μL, 108 cfu/mL) were treated with different concentrations of BQAS. Colony count assay of (C) E. coli and (D) S. aureus bacterial cells treated separately with (a) 0, (b) 12.5, (c) 25, (d) 50, (e) 100, and (f) 200 μg/mL of BQAS.

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Table 1. MICs of BQAS Against Three Strains of Gram-Positive Bacteria and Gram-Negative Bacteria
microorganism MIC (μg/mL)
E. coli (AB 93154) 16
E. coli (EAEC 36) 64
E. coli (EPEC 2-1) 32
S. aureus (AB 91093) 16
S. aureus (1213P46B) 8
S. aureus (011P6B5A) 32
The death rates also showed that BQAS has an excellent bactericidal activity against both Gram-negative and Gram-positive bacteria. In Figure 3, the death rates gradually ascended with an increasing concentration of BQAS. The death rates for E. coli and S. aureus were 35.91 and 36.48% at the concentration of 12.5 μg/mL, and 84.02 and 94.93% at the concentration of 25 μg/mL, respectively. The bacterial inhibition of BQAS reached over 99% at the concentration of 50 μg/mL, and with the concentration of BQAS increased from 12.5 to 200 μg/mL, the death rates of both E. coli and S. aureus increased to 99.99%. A comparison of antibacterial activity between BQAS and CTAB was performed under the same experimental conditions. Figure 3 showed the death rates of E. coli and S. aureus treated with CTAB (12.5–200 μg/mL). A significant difference of antibacterial effect could be observed between CTAB and BQAS at low concentrations. For example, BQAS showed 74 and 94.93% inactivation effect on E. coli and S. aureus at a concentration of 25 μg/mL, respectively. However, CTAB exhibited only about 55.2 and 50.46% inactivation effect on the two strains at the same concentration (Figure 3). The results indicated that BQAS had a higher antibacterial activity than CTAB at low concentrations. Additionally, BQAS displayed a stronger inhibition effect on S. aureus than E. coli at low concentrations.

Figure 3

Figure 3. Cell death rates of (A) E. coli and (B) S. aureus after incubation with BQAS and CTAB dispersions at different concentrations (0–200 μg/mL) for 3 h at 30 °C. E. coli and S. aureus untreated with BQAS or CTAB were used as control. Error bars represent the standard deviation.

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The credibility of the cfu method was further confirmed by the live/dead bacterial staining assay. PI (propidium iodide) and DAPI (4′-6-diamidino-2-phenylindole) are fluorescent dyes. PI can only pass through the damaged structures of the cell membrane, stain the nucleus, and emit red fluorescence, whereas DAPI can penetrate the intact membrane of live cells, combine strongly with DNA, and emit blue fluorescence. Therefore, PI and DAPI are usually used to identify dead cells and live cells, (31) respectively. As shown in Figure 4, the red fluorescence became gradually strong and the blue fluorescence became weak with the increasing concentration of BQAS, suggesting that the dead bacterial cells ascended with the increasing concentration of BQAS. The result was not only in accordance with the above results, but also implied that the cell membranes were seriously damaged.

Figure 4

Figure 4. Fluorescence microscopic images of E. coli (top panel) and S. aureus (bottom panel) (cells stained with PI and DAPI) after exposure to BQAS at concentrations of (A) 0, (B) 12.5, (C) 25, (D) 50, (E) 100, and (F) 200 μg/mL, respectively.

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The morphological changes and membrane integrity of E. coli and S. aureus bacterial cells treated with BQAS were observed using a scanning electron microscope and transmission electron microscope. As shown in Figure 5A,C, in the absence of BQAS, the shapes of both E. coli and S. aureus cells were typically rod-shaped and round, respectively, with a smooth and intact cell wall to protect the bacterial cells and maintain their life. (33) However, after treatment with 200 μg/mL BQAS, significant changes can be observed in the bacterial morphology. As shown in Figure 5B,D, a large number of E. coli and S. aureus cell walls crumpled and collapsed into holes and debris (the magnified images showed a rather clear change), leading to the inactivity of the bacterial cells.

Figure 5

Figure 5. SEM images of E. coli (A,B) and S. aureus (C,D), untreated with BQAS (A,C) and treated with BQAS (B,D). A 200 μL of BQAS (200 μg/mL) was incubated with 200 μL of bacterial dispersion (108 cfu/mL) for 3 h at a shaking speed of 120 rpm at 30 °C.

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In addition, the membrane disruption and the inner changes of the cells were confirmed by TEM (Figure 6). When the cells were treated with 200 μg/mL of BQAS, the bacterial cells of E. coli (Figure 6B) and S. aureus (Figure 6D) showed significant changes in morphology compared with the untreated bacterial cells, with the treated bacterial cell walls being blurred or the edges partially dissolved, similar to previous reports. (34) These results further indicated that BQAS was an effective antibacterial agent.

Figure 6

Figure 6. TEM images of E. coli (A,B) and S. aureus (C,D), untreated with BQAS (A,C) and treated with BQAS (B,D). A 200 μL of BQAS (200 μL/mL) was incubated with 200 μL of bacterial dispersion (108 cfu/mL) for 3 h at a shaking speed of 120 rpm at 30 °C.

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The significant morphological changes in the structure of bacterial cells could be attributed to the detachment of the cytoplasmic membrane from the cell wall, as determined by the lactic acid dehydrogenase (LDH) release assay. Figure 7A exhibited the LDH activity in the supernatant after treatment with BQAS for 3 h. It can be observed that the release of LDH was concentration-dependent. The bacterial cells treated with 12.5 μg/mL of BQAS showed a minimal release of LDH. However, when the concentration of BQAS was increased to 200 μg/mL, the LDH release significantly ascended, with a cytotoxicity of 84.2 and 83.77% for E. coli and S. aureus, respectively.

Figure 7

Figure 7. (A) BQAS cytotoxicity measured by the LDH release from the bacterial cells after treatment with different concentrations (0–200 μg/mL) of BQAS for 3 h. (B) Release of protein from bacteria treated with BQAS (0–200 μg/mL). Bacterial cells (108 cfu/mL) incubated with 200 μL of different concentrations (0–200 μg/mL) of BQAS at 30 °C for 3 h at a shaking speed of 120 rpm. Error bars represent the standard deviation (n = 3).

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The release of cytoplasmatic content was further detected in terms of DNA and protein (Figures S4 and 7B). It can be clearly seen that after incubation with different concentrations of BQAS, strips appeared. Interestingly, the intensity of the strips varied obviously with the different BQAS concentrations, the intensity of the DNA strips being stronger at low concentrations than at high concentrations. The results not only indicated that the DNA was degraded to a certain degree at a high BQAS concentration because the generated reactive oxygen species (ROS) had an activity of oxidizing the nucleic acid, (35) but also confirmed that the cell membrane of the bacteria was indeed damaged.
Figure 7B showed the leakage of proteins after interaction with BQAS. The absorbance at an optical density of 590 nm (OD590nm) reflected the level of the leaked proteins. Compared with the group untreated with BQAS, the values of OD590nm of the treatment groups increased with the increasing concentration of BQAS, indicating that the leakage of protein was dose-dependent. The significant increase of the leaked proteins in the bacteria verified that the bacterial cell membrane was severely damaged because of the direct contact of the bacteria with BQAS. The above results fully demonstrated that the bacterial cell walls were damaged and the inner contents leaked out, eventually leading to the inhibition of the bacterial growth.
The above results are consistent with previous studies reporting that several nanomaterials exhibited a stronger antibacterial activity against Gram-positive than Gram-negative bacteria. (34,36) This difference in sensitivity to nanomaterials can be attributed to their different cell wall structures. (37,38) The cellular membranes of Gram-negative E. coli have negative charges, with pI (isoelectric point) = 4–5. However, the pI value of Gram-positive S. aureus membranes is higher than that of E. coli, which can generate a more negatively charged surface in a culture medium at pH 7 (Figure S3). BQAS has a highly positive surface charge (ζ-potential ca. +30.2 mV) and can induce a stronger contact with S. aureus. Previous findings have indicated that the highly positive charge causes a severe disruption of the bacterial membrane. (39) To understand the mechanism of reversible antibacterial control, zeta potential measurements were carried out to study the interaction between bacteria and BQAS. As shown in Figure 8, the potentials of BQAS exhibited remarkable changes with the addition of BSA. Previous reports have shown that cationic conjugated oligomers/polymers with QA groups as side chains could bind and insert into the negatively charged membrane of bacteria by electrostatic and hydrophobic interactions. (40,41) Inserting into the membrane by hydrophobic interactions does not affect the zeta potential of bacteria, but binding by electrostatic interactions leads to a remarkable positive potential shift. We further measured the ζ-potential and examined the antibacterial activity of BQAS. As shown in Figure 8A, the ζ-potential values of BQAS and BQAS–BSA are significantly different; the ζ-potential values of BQAS containing 1 and 5 μM BSA are ca. +10 and +3 mV, respectively. A 12.5 μg/mL BQAS was used to compare the antibacterial properties of BQAS with BQAS–BSA, and the results are presented in Figure 8B. Further, the MICs of BQAS and BSA-modified BQAS against S. aureus and E. coli were also measured (Table 2). It can be seen that the antibacterial activity significantly decreased with the addition of BSA, suggesting that BQAS rich in positive charge favors its antibacterial activity, leading to a strong electrostatic interaction with the bacterial membrane, and then caused severe damage to the integrity of the cell membrane, induced the leakage of intracellular contents, and ultimately resulted in bacterial death.

Figure 8

Figure 8. (A) Zeta potential of BQAS in the absence and presence of BSA and (B) death rate of S. aureus and E. coli for the treatments of BQAS in the absence and presence of BSA. Error bars represent the standard deviation of three repeated measurements.

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Table 2. MICs of BQAS and BSA–BQAS Against Three Strains of Gram-Positive Bacteria and Gram-Negative Bacteria
  MIC (μg/mL)
microorganism BQAS +5 μM BSA
E. coli 16 32
S. aureus 16 32
Several previous studies have proposed that ROS contributed to the antibacterial activity of many materials. (34,35,42,43) Oxidative stress occurs when cells are exposed to elevated levels of ROS such as free radicals, •O2–, •OH, and H2O2. Figure 9 shows the electron spin resonance (ESR) spectra of ROS generated by BQAS in the absence of bacteria. BQAS generated both •OH (Figure 9A) and •O2– (Figure 9B) signals, with •O2– as the main species.

Figure 9

Figure 9. ESR spectra of (A) DMPO-•OH and (B) DMPO-•O2– for BQAS.

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ROS was measured with an oxidation-sensitive fluorescent probe 2,7-dichlorofluorescein diacetate (DCFH-DA). The ROS level is correlated with the antibacterial activity of the material because of its damaging effect on the bacterial cell membrane. When the materials affect the cell membrane, ROS is formed, and DCFH-DA inside the cell reacts with the ROS to form a fluorescent by-product. As displayed in Figure 10A,D, almost no green fluorescence was observed in the absence of BQAS. However, in Figure 10B,C,E,F, the green fluorescence intensity became stronger with the increasing concentration of BQAS, demonstrating an increase of the endogenous oxidative level in this study. (44) As shown in Figure S5, little green fluorescence could be observed in the absence of BQAS, implying that almost no ROS was produced. In contrast, under the treatment of 200 μg/mL BQAS, the green fluorescence intensity was 5.5 and 4.1 times greater than that of the control group.

Figure 10

Figure 10. Intracellular ROS staining results of E. coli (A–C) and S. aureus (D–F) bacterial cells after treatment with (A) 0, (B) 50, and (C) 200 μg/mL of BQAS, respectively. Bacterial suspensions in deionized water without BQAS were used as control.

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The peroxidation environment makes a contribution to the physiological changes of bacterial cells, such as the depolarization of cell membrane and the release of protein and DNA/RNA, which result from the permeability increase of the membrane. (45) To identify whether the cellular oxidative stress is induced by BQAS, the ROS-dependent oxidative stress was investigated. The production of superoxide anion (•O2–) at different BQAS concentrations was monitored using the Superoxide Assay Kit (Beyotime Biotechnology). As shown in Figure S6, the absorption values increased notably with an increasing BQAS concentration, revealing that BQAS mediated superoxide anion production, which played an important role in antibacterial activity.
Good cell compatibility is essential for the antibacterial agents to be used in vivo. The effect of BQAS on the viability of 4T1 cells was evaluated by employing an MTT cytotoxicity assay. As shown in Figure S7, compared with the control, BQAS displayed no obvious effect on the proliferation of 4T1 cells within the concentration of 50 μg/mL, which means that BQAS had a negligible toxicity to cells and that the cell viability was about 90%. The result indicated that BQAS could be safely used in vivo.

Conclusions

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In summary, our studies indicated that BQAS exhibited a broad bactericidal activity against both Gram-negative E. coli and Gram-positive S. aureus in vitro, and the bactericidal activity was concentration-dependent and superior to that of CTAB. Meanwhile, S. aureus was found to be more sensitive to BQAS than E. coli because of the different cell wall structures. BQAS has a highly positive surface charge (ζ-potential ca. +30.2 mV) and can induce a strong contact with the bacterial membrane. The leakage of the inner cell contents indicated that the exposure of bacteria to BQAS leads to ROS generation and the destruction of the cell membrane. This study demonstrated that the combination of a highly positive charge and ROS generation is an effective approach to improve the antibacterial activity of a bactericidal material. The integrated data indicated that BQAS had a great potential for therapy against bacterial infections.

Experimental Section

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Materials

1,3-Dichloro-2-propanol, N,N-dimethyldodecylamine, propanol, ethylacetate, PI, and DAPI products were purchased from Aladdin Industrial Corporation (Shanghai, China). The superoxide detection kit and reactive oxygen test kit were purchased from Beyotime Biotechnology (Shanghai, China). The cytotoxicity detection kit was purchased from Roche Applied Science (Shanghai, China).

Synthesis and Characterization of BQAS

BQAS was synthesized by a one-step pathway with 1,3-dichloro-2-propanol and N,N-dimethyldodecylamine by using the condensate reflow device only. (25,46) The molecular structure of BQAS was characterized by FT-IR spectroscopy and MS, and zeta potential was also used to analyze the obtained BQAS.

Bacterial Culture

E. coli (AB 93154) and S. aureus (AB 91093) were selected as Gram-negative and Gram-positive bacteria, respectively, and acquired from China Center for Type Culture Collection. All the bacterial strains were stored at −80 °C in Luria Bertani (LB) with 30% glycerol. The bacteria were cultured in an LB broth medium (10 g L–1 peptone, 5 g L–1 yeast extract, 10 g L–1 NaCl, sterilization for 20 min at 121 °C and 101 kPa, and stored at 4 °C for further use) at 30 °C on a shaker bed at 120 rpm overnight. Then, the bacterial suspension was washed twice with deionized water by centrifugation (3000 rpm, 5 min), followed by dilution with deionized water to a concentration of 108 cfu/mL for further experiments.

Antimicrobial Activity Test of BQAS

The antimicrobial activity of BQAS was evaluated by measuring OD and by the colony count method. The OD growth curves were obtained as follows. Briefly, the logarithmic-phase bacteria (0.2 mL 1 × 108 cfu/mL) were centrifuged at 3000 rpm for 5 min and washed in deionized water, followed by discarding the supernatant. Then, the precipitates were mixed separately with different concentrations of the BQAS aqueous solution (12.5, 25, 50, 100, and 200 μg/mL), and sterile water was used instead of BQAS as the control group. Next, the mixtures were subjected to continuous shaking at 120 rpm and 30 °C for 3 h and then transferred to a 20 mL LB medium for further incubation at 30 °C in a constant-temperature oscillator under 120 rpm rotation. Finally, aliquots of the samples were withdrawn at 1 hour interval, and the value of OD at a wavelength of 600 nm (OD600) was measured on a Multiskan Spectrum.
The colony count method was adopted as follows. Briefly, the bacteria (1 × 108 cfu/mL) were incubated with different concentrations of BQAS at 30 °C for 3 h. The aliquots of the samples were withdrawn, and cfu was counted by plating 20 μL of 10-fold serial dilutions onto LB agar plates and cultured at 30 °C for 24 h. The control group consisted of the bacteria untreated with BQAS. The colonies were counted, and the bacterial death rate was calculated according to the following formula
(1)

Fluorescence Microscopic Observation (Live/Dead)

The death rates were further verified via the live/dead viability assay after treatment with BQAS. Briefly, 200 μL bacterial suspensions were mixed with 200 μL BQAS at different concentrations (0, 12.5, 25, 50, 100, and 200 μg/mL) and incubated in a rotary shaker at 120 rpm for 3 h at 30 °C. Then, an appropriate volume of the bacterial suspension was stained with PI and DAPI for 20 and 3 min in the dark sequentially. Finally, the fluorescence images were taken on a fluorescence microscope.

Cell Morphology Observation

SEM and TEM analyses were performed to evaluate the effect of BQAS on the morphology and structure of cells. SEM imaging was conducted as follows. Briefly, the bacterial cells were incubated with BQAS, followed by washing twice with sterile water. Then, fixation with 2.5% glutaraldehyde for 4 h at room temperature and successive dehydration with a gradient concentration of ethanol (30, 50, 70, 90, and 100%) for 15 min were performed. Finally, the samples were dried in a vacuum oven and then coated with gold via sputtering for SEM, and the samples were dropped on copper grids for TEM.

Lactase Dehydrogenase Release Experiments

The LDH release assay was performed to verify the cell membrane activity of bacterial cells treated with BQAS using the LDH cytotoxicity assay kit (Roche Applied Science). (47) The standard protocol assay was conducted according to the manufacturer’s instructions. Briefly, the E. coli and S. aureus cells were treated with BQAS at concentrations of 12.5, 25, 50, 100, and 200 μg/mL for 3 h, followed by transferring 120 μL of each cell culture supernatant into a new centrifuge tube and then adding 60 μL of substrate. After incubation at room temperature in the dark for 30 min, the reaction was stopped by adding 50 μL of the stop solution. Finally, the LDH release was quantified by monitoring the absorbance at 490 nm.

Determination of Intracellular ROS

The ROS production was evaluated by using DCFH-DA, a nonfluorescent compound, which can readily diffuse into water and interact with ROS. After incubation with different concentrations of BQAS for 3 h, the bacterial suspensions were washed and stained with 10 μm DCFH-DA (Beyotime Biotechnology) for 20 min in dark at 25 °C. Green fluorescent ROS-producing cells were visualized with a fluorescence microscope at a 488 nm excitation wavelength. The areas of observation were randomly photographed with a Nikon fluorescence microscope.
The possibility of superoxide anion (O2•–) production was evaluated to determine the oxidative stress using the superoxide assay kit (Beyotime Biotechnology). Briefly, 200 μL of the bacterial suspension was centrifuged and washed twice with sterile water, followed by adding 200 μL of detection solution and incubating at 37 °C for 5–10 min. Next, the bacterial samples were incubated with different concentrations of BQAS under the same conditions as described above. Finally, the samples were examined by a microplate absorbance reader at 450 nm.

Leakage of Intracellular Components

To further verify the destruction of the cell membrane, related experiments were performed to evaluate the release of protein and DNA of the bacterial cells. The protein content was measured with a BCA protein assay kit (Beyotime Biotechnology), and DNA was examined by agarose gels.

Supporting Information

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsomega.8b01265.

  • Structural formula and MS spectrum of BQAS; antibacterial activity of BQAS; zeta potential of bacteria; DNA strides of bacterial cells; ROS generation; intracellular superoxide levels; MICs of BQAS against different strains of bacteria (PDF)

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Author Information

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  • Corresponding Author
    • Heyou Han - State Key Laboratory of Agricultural Microbiology, College of Science  and  State Key Laboratory of Agricultural Microbiology, College of Food Science and Technology, and , Huazhong Agricultural University, Wuhan 430070, PR China;  Orcidhttp://orcid.org/0000-0001-9406-0722;  Email: [email protected]
  • Authors
    • Zhiyong Song - State Key Laboratory of Agricultural Microbiology, College of Science, and , Huazhong Agricultural University, Wuhan 430070, PR China;  Orcidhttp://orcid.org/0000-0002-2552-5239
    • Huajuan Wang - State Key Laboratory of Agricultural Microbiology, College of Food Science and Technology, and , Huazhong Agricultural University, Wuhan 430070, PR China
    • Yang Wu - State Key Laboratory of Agricultural Microbiology, College of Science, and , Huazhong Agricultural University, Wuhan 430070, PR China
    • Jiangjiang Gu - State Key Laboratory of Agricultural Microbiology, College of Science, and , Huazhong Agricultural University, Wuhan 430070, PR China
    • Shuojun Li - State Key Laboratory of Agricultural Microbiology, College of Science, and , Huazhong Agricultural University, Wuhan 430070, PR China
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors are grateful to the financial support by the National Natural Science Foundation of China (21778020), the Fundamental Research Funds for the Central Universities (grant no. 2662016QD027), Sci-tech Innovation Foundation of Huazhong Agriculture University (2662017PY042). The authors are also thankful to Xuedong Jia’s group in the School of Chemistry and Chemical Engineering, Nanjing University for material synthesis and technical support.

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This article references 47 other publications.

  1. 1
    Subbiahdoss, G.; Sharifi, S.; Grijpma, D. W.; Laurent, S.; van der Mei, H. C.; Mahmoudi, M.; Busscher, H. J. Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci. Acta Biomater. 2012, 8, 2047– 2055,  DOI: 10.1016/j.actbio.2012.03.002
    Google Scholar
    1
    Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci
    Subbiahdoss, Guruprakash; Sharifi, Shahriar; Grijpma, Dirk W.; Laurent, Sophie; van der Mei, Henny C.; Mahmoudi, Morteza; Busscher, Henk J.
    Acta Biomaterialia (2012), 8 (6), 2047-2055CODEN: ABCICB; ISSN:1742-7061. (Elsevier Ltd.)
    Biofilms on biomaterial implants are hard to eradicate with antibiotics due to the protection offered by the biofilm mode of growth, esp. when caused by antibiotic-resistant strains. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as targeted drug delivery and magnetic resonance imaging. Here, we evaluate the hypothesis that SPIONs can be effective in the treatment of biomaterial-assocd. infection. SPIONs can be targeted to the infection site using an external magnetic field, causing deep penetration in a biofilm and possibly effectiveness against antibiotic-resistant strains. We report that carboxyl-grafted SPIONs, magnetically concd. in a biofilm, cause an approx. 8-fold higher percentage of dead staphylococci than does gentamicin for a gentamicin-resistant strain in a developing biofilm. Moreover, magnetically concd. carboxyl-grafted SPIONs cause bacterial killing in an established biofilm. Thus magnetic targeting of SPIONs constitutes a promising alternative for the treatment of costly and recalcitrant biomaterial-assocd. infections by antibiotic-resistant strains.
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  2. 2
    Rizzello, L.; Pompa, P. P. Nanosilver-based antibacterial drugs and devices: mechanisms, methodological drawbacks, and guidelines. Chem. Soc. Rev. 2014, 43, 1501– 1518,  DOI: 10.1039/c3cs60218d
    Google Scholar
    2
    Nanosilver-based antibacterial drugs and devices: Mechanisms, methodological drawbacks, and guidelines
    Rizzello, Loris; Pompa, Pier Paolo
    Chemical Society Reviews (2014), 43 (5), 1501-1518CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    Despite the current advancement in drug discovery and pharmaceutical biotechnol., infection diseases induced by bacteria continue to be one of the greatest health problems worldwide, afflicting millions of people annually. Almost all microorganisms have, in fact, an intrinsic outstanding ability to flout many therapeutic interventions, thanks to their fast and easy-to-occur evolutionary genetic mechanisms. At the same time, big pharmaceutical companies are losing interest in new antibiotics development, shifting their capital investments in much more profitable research and development fields. New smart solns. are, thus, required to overcome such concerns, and should combine the feasibility of industrial prodn. processes with cheapness and effectiveness. In this framework, nanotechnol.-based solns., and in particular silver nanoparticles (AgNPs), have recently emerged as promising candidates in the market as new antibacterial agents. AgNPs display, in fact, enhanced broad-range antibacterial/antiviral properties, and their synthesis procedures are quite cost effective. However, despite their increasing impact on the market, many relevant issues are still open. These include the mol. mechanisms governing the AgNPs-bacteria interactions, the physico-chem. parameters underlying their toxicity to prokaryotes, the lack of standardized methods and materials, and the uncertainty in the definition of general strategies to develop smart antibacterial drugs and devices based on nanosilver. In this review, we analyze the exptl. data on the bactericidal effects of AgNPs, discussing the complex scenario and presenting the potential drawbacks and limitations in the techniques and methods employed. Moreover, after analyzing in depth the main mechanisms involved, we provide some general strategies/procedures to perform antibacterial tests of AgNPs, and propose some general guidelines for the design of antibacterial nanosystems and devices based on silver/nanosilver.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFWhtrk%253D&md5=24e5e696c703fd263e5ec33fbd5f84ac
  3. 3
    Liu, C.; Xie, X.; Zhao, W.; Liu, N.; Maraccini, P. A.; Sassoubre, L. M.; Boehm, A. B.; Cui, Y. Conducting Nanosponge Electroporation for Affordable and High-Efficiency Disinfection of Bacteria and Viruses in Water. Nano Lett. 2013, 13, 4288– 4293,  DOI: 10.1021/nl402053z
    Google Scholar
    3
    Conducting nanosponge electroporation for affordable and high-efficiency disinfection of bacteria and viruses in water
    Liu, Chong; Xie, Xing; Zhao, Wenting; Liu, Nian; Maraccini, Peter A.; Sassoubre, Lauren M.; Boehm, Alexandria B.; Cui, Yi
    Nano Letters (2013), 13 (9), 4288-4293CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    High-efficiency, affordable, and low energy water disinfection methods are in great need to prevent diarrheal illness, which is one of the top five leading causes of death over the world. Traditional water disinfection methods have drawbacks including carcinogenic disinfection byproducts formation, energy and time intensiveness, and pathogen recovery. Here, we report an innovative method that achieves high-efficiency water disinfection by introducing nanomaterial-assisted electroporation implemented by a conducting nanosponge filtration device. The use of one-dimensional (1D) nanomaterials allows electroporation to occur at only several volts, which is 2 to 3 orders of magnitude lower than that in traditional electroporation applications. The disinfection mechanism of electroporation prevents harmful byproduct formation and ensures a fast treatment speed of 15,000 L/(h·m2), which is equal to a contact time of 1 s. The conducting nanosponge made from low-cost polyurethane sponge coated with carbon nanotubes and silver nanowires ensures the device's affordability. This method achieves more than 6 log (99.9999%) removal of four model bacteria, including Escherichia coli, Salmonella enterica typhimirium, Enterococcus faecalis, and Bacillus subtilis, and more than 2 log (99%) removal of one model virus, bacteriophage MS2, with a low energy consumption of only 100 J/L.
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  4. 4
    Fischbach, M. A.; Walsh, C. T. Antibiotics for Emerging Pathogens. Science 2009, 325, 1089– 1093,  DOI: 10.1126/science.1176667
    Google Scholar
    4
    Antibiotics for Emerging Pathogens
    Fischbach, Michael A.; Walsh, Christopher T.
    Science (Washington, DC, United States) (2009), 325 (5944), 1089-1093CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    A review. Antibiotic-resistant strains of pathogenic bacteria are increasingly prevalent in hospitals and the community. New antibiotics are needed to combat these bacterial pathogens, but progress in developing them has been slow. Historically, most antibiotics have come from a small set of mol. scaffolds whose functional lifetimes have been extended by generations of synthetic tailoring. The emergence of multidrug resistance among the latest generation of pathogens suggests that the discovery of new scaffolds should be a priority. Promising approaches to scaffold discovery are emerging; they include mining underexplored microbial niches for natural products, designing screens that avoid rediscovering old scaffolds, and repurposing libraries of synthetic mols. for use as antibiotics.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVersrzK&md5=96d902c55376951663e06dcddf0d571d
  5. 5
    Shirley, D.; Chrom, C. L.; Caputo, G. A. Membrane Binding and Antimicrobial Activity of a Catioinc, Porphyrin-Binding Peptide. Biophys. J. 2017, 112, 380a,  DOI: 10.1016/j.bpj.2016.11.2066
    Google Scholar
    There is no corresponding record for this reference.
  6. 6
    Li, P.; Poon, Y. F.; Li, W.; Zhu, H.-Y.; Yeap, S. H.; Cao, Y.; Qi, X.; Zhou, C.; Lamrani, M.; Beuerman, R. W.; Kang, E.-T.; Mu, Y.; Li, C. M.; Chang, M. W.; Leong, S. S. J.; Chan-Park, M. B. A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability. Nat. Mater. 2011, 10, 149– 156,  DOI: 10.1038/nmat2915
    Google Scholar
    6
    A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability
    Li, Peng; Poon, Yin Fun; Li, Weifeng; Zhu, Hong-Yuan; Yeap, Siew Hooi; Cao, Ye; Qi, Xiaobao; Zhou, Chuncai; Lamrani, Mouad; Beuerman, Roger W.; Kang, En-Tang; Mu, Yuguang; Li, Chang Ming; Chang, Matthew W.; Leong, Susanna Su Jan; Chan-Park, Mary B.
    Nature Materials (2011), 10 (2), 149-156CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
    Despite advanced sterilization and aseptic techniques, infections assocd. with medical implants have not been eradicated. Most present coatings cannot simultaneously fulfil the requirements of antibacterial and antifungal activity as well as biocompatibility and reusability. Here, we report an antimicrobial hydrogel based on dimethyldecylammonium chitosan (with high quaternization)-graft-poly(ethylene glycol) methacrylate (DMDC-Q-g-EM) and poly(ethylene glycol) diacrylate, which has excellent antimicrobial efficacy against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Fusarium solani. The proposed mechanism of the antimicrobial activity of the polycationic hydrogel is by attraction of sections of anionic microbial membrane into the internal nanopores of the hydrogel, like an 'anion sponge', leading to microbial membrane disruption and then microbe death. We have also demonstrated a thin uniform adherent coating of the hydrogel by simple UV immobilization. An animal study shows that DMDC-Q-g-EM hydrogel coating is biocompatible with rabbit conjunctiva and has no toxicity to the epithelial cells or the underlying stroma.
    >> More from SciFinder ®
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  7. 7
    Kang, S.; Pinault, M.; Pfefferle, L. D.; Elimelech, M. Single-walled carbon nanotubes exhibit strong antimicrobial activity. Langmuir 2007, 23, 8670– 8673,  DOI: 10.1021/la701067r
    Google Scholar
    7
    Single-Walled Carbon Nanotubes Exhibit Strong Antimicrobial Activity
    Kang, Seoktae; Pinault, Mathieu; Pfefferle, Lisa D.; Elimelech, Menachem
    Langmuir (2007), 23 (17), 8670-8673CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    The authors provide the first direct evidence that highly purified single-walled carbon nanotubes (SWNTs) exhibit strong antimicrobial activity. By using a pristine SWNT with a narrow diam. distribution, the authors demonstrate that cell membrane damage resulting from direct contact with SWNT aggregates is the likely mechanism leading to bacterial cell death. This finding may be useful in the application of SWNTs as building blocks for antimicrobial materials.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXnvFOltbY%253D&md5=2085cc562720db0e2cea9eb23ba3fc12
  8. 8
    Wang, X.; Liu, X.; Han, H. Evaluation of antibacterial effects of carbon nanomaterials against copper-resistant Ralstonia solanacearum. Colloids Surf., B 2013, 103, 136– 142,  DOI: 10.1016/j.colsurfb.2012.09.044
    Google Scholar
    8
    Evaluation of antibacterial effects of carbon nanomaterials against copper-resistant Ralstonia solanacearum
    Wang, Xiuping; Liu, Xueqin; Han, Heyou
    Colloids and Surfaces, B: Biointerfaces (2013), 103 (), 136-142CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
    The authors investigated the antibacterial activity and the action mode of carbon nanomaterials (CNMs) against the copper-resistant plant pathogenic bacterium Ralstonia solanacearum (R. solanacearum). Single-walled carbon nanotubes (SWCNTs) dispersion was found to show the strongest antibacterial activity, sequentially followed by graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO) and fullerene (C60). This investigation of the antibacterial mechanism of SWCNTs and GO indicated that the damage to the cell membrane leads to the release of cytoplasm materials from the bacterium, which is the causative factor for the inactivation of R. solanacearum bacterial cells. The superior antibacterial effect, and the novel antibacterial mode of SWCNTs and GO suggest that those carbon nanomaterials may have important applications in the control of plant bacterial diseases.
    >> More from SciFinder ®
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  9. 9
    Liu, S.; Zeng, T. H.; Hofmann, M.; Burcombe, E.; Wei, J.; Jiang, R.; Kong, J.; Chen, Y. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress. ACS Nano 2011, 5, 6971– 6980,  DOI: 10.1021/nn202451x
    Google Scholar
    9
    Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: Membrane and oxidative stress
    Liu, Shao-Bin; Zeng, Ting-Ying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rong-Rong; Kong, Jing; Chen, Yuan
    ACS Nano (2011), 5 (9), 6971-6980CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model: Escherichia coli. Under similar concn. and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest av. size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O2·-) induced reactive oxygen species (ROS) prodn. is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidn. capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidn. stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidn. The authors envision that physicochem. properties of graphene-based materials, such as d. of functional groups, size, and cond., can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials.
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  10. 10
    Ivankin, A.; Livne, L.; Mor, A.; Caputo, G. A.; DeGrado, W. F.; Meron, M.; Lin, B.; Gidalevitz, D. Role of the conformational rigidity in the design of biomimetic antimicrobial compounds. Angew. Chem., Int. Ed. 2010, 49, 8462– 8465,  DOI: 10.1002/anie.201003104
    Google Scholar
    10
    Role of the Conformational Rigidity in the Design of Biomimetic Antimicrobial Compounds
    Ivankin, Andrey; Livne, Liran; Mor, Amram; Caputo, Gregory A.; DeGrado, William F.; Meron, Mati; Lin, Binhua; Gidalevitz, David
    Angewandte Chemie, International Edition (2010), 49 (45), 8462-8465, S8462/1-S8462/3CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Antimicrobial peptides (AMPs) are naturally occurring antibiotics found in essentially all living organisms. In the past two decades, AMPs have attracted considerable interest because of their potential therapeutic use as antiinfective agents. There exists, however, a no. of serious challenges preventing AMP from reaching a pharmaceutical market including their rapid in vivo degrdn., high prodn. costs, and reduced activity in physiol. conditions. Efforts to overcome these problems while retaining the peptides' natural antiinfective properties resulted in the emergence of a rapidly expanding field of nonnatural mimics of antimicrobial peptides. Good understanding of the structure-activity relationships in AMPs is essential in the effort to create a successful peptidomimetic compd. The authors have reported results of the first X-ray study of interactions between nonnatural AMP mimics and model bacterial membranes aimed at understanding the role of structural flexibility on the activity of antimicrobials. The results show that conformational flexibility does not prevent antimicrobials from exerting a strong membrane-disruptive activity. In addn., we have demonstrated that while penetration of lipid A represents a serious challenge for the conformationally rigid antimicrobials, the flexible OAK-I incorporates into lipid A with the same propensity as into DPPG. This implies that the structured and flexible antimicrobials act on the bacterial outer membrane differently. In recent years, a no. of novel synthetic oligomers and linear polymers with favorable antimicrobial efficacy, yet no specific or regular conformation, have been identified. Our results will aid in the rational design and optimization of emerging and future nonnatural antimicrobial agents.
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  11. 11
    Ghosh, C.; Manjunath, G. B.; Akkapeddi, P.; Yarlagadda, V.; Hoque, J.; Uppu, D. S. S. M.; Konai, M. M.; Haldar, J. Small molecular antibacterial peptoid mimics: the simpler the better!. J. Med. Chem. 2014, 57, 1428– 1436,  DOI: 10.1021/jm401680a
    Google Scholar
    11
    Small molecular antibacterial peptoid mimics: the simpler the better!
    Ghosh, Chandradhish; Manjunath, Goutham B.; Akkapeddi, Padma; Yarlagadda, Venkateswarlu; Hoque, Jiaul; Uppu, Divakara S. S. M.; Konai, Mohini M.; Haldar, Jayanta
    Journal of Medicinal Chemistry (2014), 57 (4), 1428-1436CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)
    The emergence of multidrug-resistant bacteria compounded by the depleting arsenal of antibiotics has accelerated efforts toward development of antibiotics with novel mechanisms of action. The authors present a series of small mol. antibacterial peptoid mimics which exhibit high in vitro potency against a variety of Gram-pos. and Gram-neg. bacteria, including drug-resistant species such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. The highlight of these compds. is their superior activity against the major nosocomial pathogen Pseudomonas aeruginosa. Nontoxic toward mammalian cells, these rapidly bactericidal compds. primarily act by permeabilization and depolarization of bacterial membrane. Synthetically simple and selectively antibacterial, these compds. can be developed into a newer class of therapeutic agents against multidrug resistant bacterial species.
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  12. 12
    Niu, Y.; Wang, M.; Cao, Y.; Nimmagadda, A.; Hu, J.; Wu, Y.; Cai, J.; Ye, X.-S. Rational Design of Dimeric Lysine N-Alkylamides as Potent and Broad-Spectrum Antibacterial Agents. J. Med. Chem. 2018, 61, 2865– 2874,  DOI: 10.1021/acs.jmedchem.7b01704
    Google Scholar
    12
    Rational design of dimeric lysine N-alkylamides as potent and broad-spectrum antibacterial agents
    Niu, Youhong; Wang, Minghui; Cao, Yafei; Nimmagadda, Alekhya; Hu, Jianxing; Wu, Yanfen; Cai, Jianfeng; Ye, Xin-Shan
    Journal of Medicinal Chemistry (2018), 61 (7), 2865-2874CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)
    Antibiotic resistance is one of the biggest threats to public health, and new antibacterial agents hence are in an urgent need to combat infectious diseases caused by multidrug-resistant (MDR) pathogens. Utilizing dimerization strategy, we rationally designed and efficiently synthesized a new series of small mol. dimeric lysine alkylamides as mimics of AMPs. Evaluation of these mimics against a panel of Gram-pos. and Gram-neg. bacteria including MDR strains was performed, and a broad-spectrum and potent compd. 3d was identified. This compd. displayed high specificity toward bacteria over mammalian cell. Time-kill kinetics and mechanistic studies suggest that compd. 3d quickly eliminated bacteria in a bactericidal mode by disrupting bacterial cell membrane. In addn., lead compd. 3d could inhibit biofilm formation and did not develop drug resistance in S. aureus and E. coli over 14 passages. These results suggested that dimeric lysine nonylamide has immense potential as a new type of novel small mol. agent to combat antibiotic resistance.
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  13. 13
    Tew, G. N.; Scott, R. W.; Klein, M. L.; DeGrado, W. F. De novo design of antimicrobial polymers, foldamers, and small molecules: from discovery to practical applications. Acc. Chem. Res. 2010, 43, 30– 39,  DOI: 10.1021/ar900036b
    Google Scholar
    13
    De Novo Design of Antimicrobial Polymers, Foldamers, and Small Molecules: From Discovery to Practical Applications
    Tew, Gregory N.; Scott, Richard W.; Klein, Michael L.; De Grado, William F.
    Accounts of Chemical Research (2010), 43 (1), 30-39CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
    A review. Antimicrobial peptides (AMPs) provide protection against a variety of pathogenic bacteria and are, therefore, an important part of the innate immune system. Over the past decade, there has been considerable interest in developing AMPs as i.v. administered antibiotics. However, despite extensive efforts in the pharmaceutical and biotechnol. industry, it has proven difficult to achieve this goal. While researchers have solved some relatively simple problems such as susceptibility to proteolysis, more severe problems have included the expense of the materials, toxicity, poor efficacy, and limited tissue distribution. In this Account, the authors describe their efforts to design and synthesize "foldamers" - short sequence-specific oligomers based on acrylamide and β-amino acid backbones, which fold into well-defined secondary structures - that could act as antimicrobial agents. The authors reasoned that small "foldamers" would be less expensive to produce than peptides, and might have better tissue distribution. It should be easier to fine-tune the structures and activities of these mols. to minimize toxicity. Because the activities of many AMPs depends primarily on their overall physicochem. properties rather than the fine details of their precise amino acid sequences, the authors have designed and synthesized very small "coarse-grained" mols., which are far simpler than naturally produced AMPs. The mol. design of these foldamers epitomizes the pos. charged amphiphilic structures believed to be responsible for the activity of AMPs. The designed oligomers show greater activity than the parent peptides. They have also provided leads for novel small mol. therapeutics that show excellent potency in animal models for multidrug resistant bacterial infections. In addn., such mols. can serve as relatively simple exptl. systems for investigations aimed at understanding the mechanism of action for this class of antimicrobial agents. The foldamers' specificity for bacterial membranes relative to mammalian membranes appears to arise from differences in membrane compn. and phys. properties between these cell types. Furthermore, because exptl. coarse-graining provided such outstanding results, the authors developed computational coarse-grained models to enable mol. dynamic simulations of these mols. with phospholipid membranes. These simulations allow investigation of larger systems for longer times than conventional mol. dynamics simulations, allowing the authors to investigate how physiol. relevant surface concns. of AMP mimics affect the bilayer structure and properties. Finally, the authors apply the principles discovered through this work to the design of inexpensive antimicrobial polymers and materials.
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  14. 14
    Agnihotri, S.; Mukherji, S.; Mukherji, S. Size-controlled silver nanoparticles synthesized over the range 5-100 nm using the same protocol and their antibacterial efficacy. RSC Adv. 2014, 4, 3974– 3983,  DOI: 10.1039/c3ra44507k
    Google Scholar
    14
    Size-controlled silver nanoparticles synthesized over the range 5-100 nm using the same protocol and their antibacterial efficacy
    Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna
    RSC Advances (2014), 4 (8), 3974-3983CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
    A systematic and detailed study for size-specific antibacterial efficacy of silver nanoparticles (AgNPs) synthesized using a co-redn. approach is presented here. Nucleation and growth kinetics during the synthesis process was precisely controlled and AgNPs of av. size 5, 7, 10, 15, 20, 30, 50, 63, 85, and 100 nm were synthesized with good yield and monodispersity. The authors found the bacteriostatic/bactericidal effect of AgNPs to be size and dose-dependent as detd. by the min. inhibitory concn. (MIC) and min. bactericidal concn. (MBC) of silver nanoparticles against four bacterial strains. Out of the tested strains, Escherichia coli MTCC 443 and Staphylococcus aureus NCIM 5201 are the most and least sensitive strains regardless of AgNP size. For AgNPs with <10 nm size, the antibacterial efficacy was significantly enhanced as revealed through delayed bacterial growth kinetics, corresponding MIC/MBC values and disk diffusion tests. AgNPs of the smallest size, i.e., 5 nm demonstrated the best results and mediated the fastest bactericidal activity against all the tested strains compared to AgNPs having 7 nm and 10 nm sizes at similar bacterial concns. TEM anal. of AgNP treated bacterial cells showed AgNPs on the cell membrane, and AgNPs internalized within the cells.
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  15. 15
    Wang, Y.-W.; Cao, A.; Jiang, Y.; Zhang, X.; Liu, J.-H.; Liu, Y.; Wang, H. Superior antibacterial activity of zinc oxide/graphene oxide composites originating from high zinc concentration localized around bacteria. ACS Appl. Mater. Interfaces 2014, 6, 2791– 2798,  DOI: 10.1021/am4053317
    Google Scholar
    15
    Superior Antibacterial Activity of Zinc Oxide/Graphene Oxide Composites Originating from High Zinc Concentration Localized around Bacteria
    Wang, Yan-Wen; Cao, Aoneng; Jiang, Yu; Zhang, Xin; Liu, Jia-Hui; Liu, Yuanfang; Wang, Haifang
    ACS Applied Materials & Interfaces (2014), 6 (4), 2791-2798CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    New materials with good antibacterial activity and less toxicity to other species attract numerous research interest. Taking advantage of zinc oxide (ZnO) and graphene oxide (GO), the ZnO/GO composites were prepd. by a facile one-pot reaction to achieve superior antibacterial properties without damaging other species. In the composites, ZnO nanoparticles (NPs), with a size of about 4 nm, homogeneously anchored onto GO sheets. The typical bacterium Escherichia coli and HeLa cell were used to evaluate the antibacterial activity and cytotoxicity of the ZnO/GO composites, resp. The synergistic effects of GO and ZnO NPs led to the superior antibacterial activity of the composites. GO helped the dispersion of ZnO NPs, slowed the dissoln. of ZnO, acted as the storage site for the dissolved zinc ions, and enabled the intimate contact of E. coli with ZnO NPs and zinc ions as well. The close contact enhanced the local zinc concn. pitting on the bacterial membrane and the permeability of the bacterial membrane and thus induced bacterial death. In addn., the ZnO/GO composites were found to be much less toxic to HeLa cells, compared to the equiv. concn. of ZnO NPs in the composites. The results indicate that the ZnO/GO composites are promising disinfection materials to be used in surface coatings on various substrates to effectively inhibit bacterial growth, propagation, and survival in medical devices.
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  16. 16
    Gupta, K.; Singh, R. P.; Pandey, A.; Pandey, A. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli. Beilstein J. Nanotechnol. 2013, 4, 345– 351,  DOI: 10.3762/bjnano.4.40
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    16
    Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus., P. aeruginosa and E. coli
    Gupta, Kiran; Singh, R. P.; Pandey, Ashutosh; Pandey, Anjana
    Beilstein Journal of Nanotechnology (2013), 4 (), 345-351, 7 pp.CODEN: BJNEAH; ISSN:2190-4286. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
    This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradn. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol-gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV-vis spectroscopy. The rate of recombination and transfer behavior of the photoexcited electron-hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram pos. (Staphylococcus aureus) and gram neg. (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concns. of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.
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  17. 17
    Ran, X.; Du, Y.; Wang, Z.; Wang, H.; Pu, F.; Ren, J.; Qu, X. Hyaluronic Acid-Templated Ag Nanoparticles/Graphene Oxide Composites for Synergistic Therapy of Bacteria Infection. ACS Appl. Mater. Interfaces 2017, 9, 19717– 19724,  DOI: 10.1021/acsami.7b05584
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    17
    Hyaluronic Acid-Templated Ag Nanoparticles/Graphene Oxide Composites for Synergistic Therapy of Bacteria Infection
    Ran, Xiang; Du, Ye; Wang, Zhenzhen; Wang, Huan; Pu, Fang; Ren, Jinsong; Qu, Xiaogang
    ACS Applied Materials & Interfaces (2017), 9 (23), 19717-19724CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Developing methods of decreasing the harm to cell and increasing the antibacterial efficiency is becoming a potential topic of medical treatments. We demonstrated a hyaluronidase-triggered photothermal platform for killing bacteria based on silver nanoparticles (AgNPs) and graphene oxide (GO). The property of the hyaluronidase (HAase)-triggered release provided excellent antibacterial activity against Staphylococcus aureus. Upon illumination of NIR light, the GO-based nanomaterials locally raised the temp., resulting in high mortality of bacteria. The HAase-triggered AgNPs releasing approach for antibacterial allows AgNPs to be protected by hyaluronic acid (HA) template without affecting mammalian cells. The nanocomposites provided antibacterial activity against S. aureus while showing low toxicity to mammal cells. In addn., the GO-HA-AgNPs are prepd. for in vivo expts. and show excellent antibacterial property in wound disinfection model.
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  18. 18
    Kim, T. I.; Kwon, B.; Yoon, J.; Park, I.-J.; Bang, G. S.; Park, Y. K.; Seo, Y.-S.; Choi, S.-Y. Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films. ACS Appl. Mater. Interfaces 2017, 9, 7908– 7917,  DOI: 10.1021/acsami.6b12464
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    18
    Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films
    Kim, Tae In; Kwon, Buki; Yoon, Jonghee; Park, Ick-Joon; Bang, Gyeong Sook; Park, YongKeun; Seo, Yeon-Soo; Choi, Sung-Yool
    ACS Applied Materials & Interfaces (2017), 9 (9), 7908-7917CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Two-dimensional (2D) nanomaterials, such as graphene-based materials and transition metal dichalcogenide (TMD) nanosheets, are promising materials for biomedical applications owing to their remarkable cytocompatibility and physicochem. properties. On the basis of their potent antibacterial properties, 2D materials have potential as antibacterial films, wherein the 2D nanosheets are immobilized on the surface and the bacteria may contact with the basal planes of 2D nanosheets dominantly rather than contact with the sharp edges of nanosheets. To address these points, in this study, we prepd. an effective antibacterial surface consisting of representative 2D materials, i.e., graphene oxide (GO) and molybdenum disulfide (MoS2), formed into nanosheets on a transparent substrate for real device applications. The antimicrobial properties of the GO-MoS2 nanocomposite surface toward the Gram-neg. bacteria Escherichia coli were investigated, and the GO-MoS2 nanocomposite exhibited enhanced antimicrobial effects with increased glutathione oxidn. capacity and partial cond. Furthermore, direct imaging of continuous morphol. destruction in the individual bacterial cells having contacts with the GO-MoS2 nanocomposite surface was characterized by holotomog. (HT) microscopy, which could be used to detect the refractive index (RI) distribution of each voxel in bacterial cell and reconstruct the three-dimensional (3D) mapping images of bacteria. In this regard, the decreases in both the vol. (67.2%) and the dry mass (78.8%) of bacterial cells that came in contact with the surface for 80 min were quant. measured, and releasing of intracellular components mediated by membrane and oxidative stress was obsd. Our findings provided new insights into the antibacterial properties of 2D nanocomposite film with label-free tracing of bacterial cell which improve our understanding of antimicrobial activities and opened a window for the 2D nanocomposite as a practical antibacterial film in biomedical applications.
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  19. 19
    Levy, S. B.; Marshall, B. Antibacterial resistance worldwide: causes, challenges and responses. Nat. Med. 2004, 10, S122– S129,  DOI: 10.1038/nm1145
    Google Scholar
    19
    Antibacterial resistance worldwide: Causes, challenges and responses
    Levy, Stuart B.; Marshall, Bonnie
    Nature Medicine (New York, NY, United States) (2004), 10 (12, Suppl.), S122-S129CODEN: NAMEFI; ISSN:1078-8956. (Nature Publishing Group)
    A review. The optimism of the early period of antimicrobial discovery has been tempered by the emergence of bacterial strains with resistance to these therapeutics. Today, clin. important bacteria are characterized not only by single drug resistance but also by multiple antibiotic resistance: the legacy of past decades of antimicrobial use and misuse. Drug resistance presents an ever-increasing global public health threat that involves all major microbial pathogens and antimicrobial drugs.
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  20. 20
    Mahmoudi, M.; Serpooshan, V. Silver-coated engineered magnetic nanoparticles are promising for the success in the fight against antibacterial resistance threat. ACS Nano 2012, 6, 2656– 2664,  DOI: 10.1021/nn300042m
    Google Scholar
    20
    Silver-Coated Engineered Magnetic Nanoparticles Are Promising for the Success in the Fight against Antibacterial Resistance Threat
    Mahmoudi, Morteza; Serpooshan, Vahid
    ACS Nano (2012), 6 (3), 2656-2664CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    The combination of patients with poor immune system, prolonged exposure to anti-infective drugs, and cross-infection has given rise to nosocomial infections with highly resistant pathogens, which is going to be a growing threat so termed "antibiotic resistance". Due to their significant antimicrobial activity, silver nanoparticles are recognized as a promising candidate to fight against resistant pathogens; however, there are two major shortcomings with these nanoparticles. First, the silver nanoparticles are highly toxic to the healthy cells; second, due to the protection offered by the biofilm mode of growth, the silver nanoparticles cannot eradicate bacterial biofilms. In order to overcome these limitations, this study introduces a new class of engineered multimodal nanoparticles comprising a magnetic core and a silver ring with a ligand gap. The results indicated promising capability of the designed multimodal nanoparticles for high-yield antibacterial effects and eradication of bacterial biofilms, while the particles were completely compatible with the cells. Utilizing a gold ring as an intermediate coating on the produced nanoparticles may exploit new opportunities for theranosis applications. This will require special consideration in future works.
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  21. 21
    Mei, L.; Lu, Z.; Zhang, W.; Wu, Z.; Zhang, X.; Wang, Y.; Luo, Y.; Li, C.; Jia, Y. Bioconjugated nanoparticles for attachment and penetration into pathogenic bacteria. Biomaterials 2013, 34, 10328– 10337,  DOI: 10.1016/j.biomaterials.2013.09.045
    Google Scholar
    21
    Bioconjugated nanoparticles for attachment and penetration into pathogenic bacteria
    Mei, Lin; Lu, Zhentan; Zhang, Wei; Wu, Zhongming; Zhang, Xinge; Wang, Yanan; Luo, Yuting; Li, Chaoxing; Jia, Yanxia
    Biomaterials (2013), 34 (38), 10328-10337CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
    As an antimicrobial agent, silver nanoparticles functionalized with both bacitracin A and polymyxin E (AgNPs-BA&PE) were designed and synthesized with complementary antibacterial functions to act against gram-pos. and gram-neg. bacteria. AgNPs-BA&PE could easily get attached and penetrate into the bacterial cell membrane through surface-immobilized BA and PE with a membrane target, resulting in up to 10-fold increase in the antibacterial activity, without the emergence of bacterial resistance. Anal. of the antimicrobial mechanism confirmed that the synthesized nanoparticles caused disorganization of the bacterial cytomembrane and leakage of cytoplasmic contents. This antimicrobial agent with better biocompatibility can promote healing of infected wounds, and has promising and useful applications in biomedical devices and antibacterial control systems.
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  22. 22
    Chellat, M. F.; Raguž, L.; Riedl, R. Targeting Antibiotic Resistance. Angew. Chem., Int. Ed. 2016, 55, 6600– 6626,  DOI: 10.1002/anie.201506818
    Google Scholar
    22
    Targeting Antibiotic Resistance
    Chellat, Mathieu F.; Raguz, Luka; Riedl, Rainer
    Angewandte Chemie, International Edition (2016), 55 (23), 6600-6626CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A review. Finding strategies against the development of antibiotic resistance is a major global challenge for the life sciences community and for public health. The past decades have seen a dramatic worldwide increase in human-pathogenic bacteria that are resistant to one or multiple antibiotics. More and more infections caused by resistant microorganisms fail to respond to conventional treatment, and in some cases, even last-resort antibiotics have lost their power. In addn., industry pipelines for the development of novel antibiotics have run dry over the past decades. A recent world health day by the World Health Organization titled "Combat drug resistance: no action today means no cure tomorrow" triggered an increase in research activity, and several promising strategies have been developed to restore treatment options against infections by resistant bacterial pathogens.
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  23. 23
    Zhao, C.; Deng, B.; Chen, G.; Lei, B.; Hua, H.; Peng, H.; Yan, Z. Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating. Nano Res. 2016, 9, 963– 973,  DOI: 10.1007/s122710.1007/s12274-016-0984-2
    Google Scholar
    23
    Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating
    Zhao, Chen; Deng, Bing; Chen, Guanchu; Lei, Bo; Hua, Hong; Peng, Hailin; Yan, Zhimin
    Nano Research (2016), 9 (4), 963-973CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)
    New types of antimicrobial systems are urgently needed owing to the emergence of pathogenic microbial strains that gain resistance to antibiotics commonly used in daily life and medical care. In this study, we developed for the first time a broad-spectrum and robust antimicrobial thin film coating based on large-area chem. vapor deposition (CVD)-grown graphene-wrapped silver nanowires (AgNWs). The antimicrobial graphene/AgNW hybrid coating can be applied on com. flexible transparent ethylene vinyl acetate/ polyethylene terephthalate (EVA/PET) plastic films by a full roll-to-roll process. The graphene/AgNW hybrid coating showed broad-spectrum antimicrobial activity against Gram-neg. (Escherichia coli) and Gram-pos. bacteria (Staphylococcus aureus), and fungi (Candida albicans). This effect was attributed to a weaker microbial attachment to the ultra-smooth graphene film and the sterilization capacity of Ag+, which is sustainably released from the AgNWs and presumably enhanced by the electrochem. corrosion of AgNWs. Moreover, the robust antimicrobial activity of the graphene/AgNW coating was reinforced by AgNW encapsulation by graphene. Furthermore, the antimicrobial efficiency could be enhanced to ∼100% by water electrolysis by using the conductive graphene/AgNW coating as a cathode. We developed a transparent and flexible antimicrobial cover made of graphene/AgNW/EVA/PET and an antimicrobial denture coated by graphene/ AgNW, to show the potential applications of the antimicrobial materials.
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  24. 24
    Huh, A. J.; Kwon, Y. J. ″Nanoantibiotics″: A new paradigm for treating infectious diseases using nanomaterials in the antibiotics resistant era. J. Controlled Release 2011, 156, 128– 145,  DOI: 10.1016/j.jconrel.2011.07.002
    Google Scholar
    24
    "Nanoantibiotics": A new paradigm for treating infectious diseases using nanomaterials in the antibiotics resistant era
    Huh, Ae Jung; Kwon, Young Jik
    Journal of Controlled Release (2011), 156 (2), 128-145CODEN: JCREEC; ISSN:0168-3659. (Elsevier B.V.)
    A review. Despite the fact that we live in an era of advanced and innovative technologies for elucidating underlying mechanisms of diseases and molecularly designing new drugs, infectious diseases continue to be one of the greatest health challenges worldwide. The main drawbacks for conventional antimicrobial agents are the development of multiple drug resistance and adverse side effects. Drug resistance enforces high dose administration of antibiotics, often generating intolerable toxicity, development of new antibiotics, and requests for significant economic, labor, and time investments. Recently, nontraditional antibiotic agents have been of tremendous interest in overcoming resistance that is developed by several pathogenic microorganisms against most of the commonly used antibiotics. Esp., several classes of antimicrobial nanoparticles (NPs) and nanosized carriers for antibiotics delivery have proven their effectiveness for treating infectious diseases, including antibiotics resistant ones, in vitro as well as in animal models. This review summarizes emerging efforts in combating against infectious diseases, particularly using antimicrobial NPs and antibiotics delivery systems as new tools to tackle the current challenges in treating infectious diseases.
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  25. 25
    McBain, A. J.; Ledder, R. G.; Moore, L. E.; Catrenich, C. E.; Gilbert, P. Effects of quaternary-ammonium-based formulations on bacterial community dynamics and antimicrobial susceptibility. Appl. Environ. Microbiol. 2004, 70, 3449– 3456,  DOI: 10.1128/AEM.70.6.3449-3456.2004
    Google Scholar
    25
    Effects of quaternary-ammonium-based formulations on bacterial community dynamics and antimicrobial susceptibility
    McBain, Andrew J.; Ledder, Ruth G.; Moore, Louise E.; Catrenich, Carl E.; Gilbert, Peter
    Applied and Environmental Microbiology (2004), 70 (6), 3449-3456CODEN: AEMIDF; ISSN:0099-2240. (American Society for Microbiology)
    Quaternary ammonium compds. (QACs) are widely used as adjuncts to hygiene in domestic cleaning products. Current concern that the increased use of such biocides in consumer products might contribute to the emergence of antibiotic resistance has led us to examine the effects of a QAC-contg. domestic cleaning fluid on the population dynamics and antimicrobial susceptibility of domestic sink drain biofilm communities. QAC susceptibilities of numerically dominant, culturable drain bacteria (15 genera, 17 species) were detd. in vitro before and after repeated QAC exposure (14 passages). A fully characterized drain microcosm was then exposed to short-term (12 days) and long-term (3 mo) dosing with a QAC-contg. domestic detergent (QD). QAC exposure of isolated cultures caused both increases (three species) and circa twofold decreases (six species) in QAC susceptibility. The susceptibility of Ralstonia sp. was considerably decreased following 14 consecutive QAC passages. Control drain microcosm biofilms maintained dynamic stability, as evidenced by culture and denaturing gradient gel electrophoresis (DGGE) anal. Bacterial population densities were largely unaffected during short-term exposure to use levels of QD, although 50% QD caused circa 10-fold viability redns. DGGE anal. supported these observations; identified the major microcosm genera as Pseudomonas, Pseudoalteromonas, Erwinia, and Enterobacter, and showed that aeromonads increased in abundance under 10 to 50% QD. Long-term exposure of the microcosms to QD did not significantly alter the pattern of antimicrobial susceptibility. These data demonstrate the recalcitrance of domestic drain biofilms toward QAC and that although repeated QAC exposure of drain isolates in pure culture results in susceptibility change in some test bacteria, such changes do not necessarily occur within complex communities.
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  26. 26
    Kawabata, N.; Nishiguchi, M. Antibacterial activity of soluble pyridinium-type polymers. Appl. Environ. Microbiol. 1988, 54, 2532– 2535
    Google Scholar
    26
    Antibacterial activity of soluble pyridinium-type polymers
    Kawabata, Nariyoshi; Nishiguchi, Masayuki
    Applied and Environmental Microbiology (1988), 54 (10), 2532-5CODEN: AEMIDF; ISSN:0099-2240.
    Cross-linked poly(N-benzyl-4-vinylpyridinium halide) (designated insol. BVP) was previously reported to capture bacterial cells alive by contact. The corresponding linear polymer, poly(N-benzyl-4-vinylpyridinium salt) (designated sol. BVP), exhibited antibacterial activity. This sol. pyridinium-type polymer showed strong antibacterial activity against gram-pos. bacteria, whereas it was less active against gram-neg. bacteria. The antibacterial activity of this cationic, polymeric disinfectant was considerably greater than that of the corresponding monomeric compd. and was approx. equal to that of conventional disinfectants such as benzalkonium chloride and chlorohexidine.
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    PMID: 3202632.

  27. 27
    Beyth, N.; Yudovin-Farber, I.; Bahir, R.; Domb, A. J.; Weiss, E. I. Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans. Biomaterials 2006, 27, 3995– 4002,  DOI: 10.1016/j.biomaterials.2006.03.003
    Google Scholar
    27
    Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans
    Beyth, Nurit; Yudovin-Farber, Ira; Bahir, Ran; Domb, Abraham J.; Weiss, Ervin I.
    Biomaterials (2006), 27 (21), 3995-4002CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
    The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1% wt./wt. with clin. used bonding, flowable and hybrid dental composite resins and cured by light polymn. was studied. The antibacterial activity was tested with Streptococcus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity (p<0.001) was found in all 3 types of composite resins incorporated with the synthesized nanoparticles. The effect lasted for at least 1 mo. SEM demonstrated bacterial debris and no streptococcal chains at 24 h of bacterial contact. The addn. of 1% wt./wt. of nanoparticles did not affect the flexural modulus and the flexural strength of the dental composite materials. The results indicate that quaternary ammonium PEI nanoparticles immobilized in resin-based materials have a strong antibacterial activity upon contact without leach-out of the nanoparticles and without compromise in mech. properties.
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  28. 28
    Gilbert, P.; McBain, A. J. Potential impact of increased use of biocides in consumer products on prevalence of antibiotic resistance. Clin. Microbiol. Rev. 2003, 16, 189– 208,  DOI: 10.1128/CMR.16.2.189-208.2003
    Google Scholar
    28
    Potential impact of increased use of biocides in consumer products on prevalence of antibiotic resistance
    Gilbert, Peter; McBain, Andrew J.
    Clinical Microbiology Reviews (2003), 16 (2), 189-208CODEN: CMIREX; ISSN:0893-8512. (American Society for Microbiology)
    A review. There has recently been much controversy surrounding the increased use of antibacterial substances in a wide range of consumer products and the possibility that, as with antibiotics, indiscriminate use of biocides might contribute to the overall pattern of susceptibility in the general environment and in the clinic. Such speculation, based on the isolation of resistant mutants from in vitro monoculture expts., is not reflected by an emergence of biocide-resistant strains in vivo. This review provides a broad coverage of the biocide and resistance literature and evaluates the potential risks, perceived from such lab. monoculture expts., against evidence gathered over 50 yr of field studies. An explanation for the continued effectiveness of broad-spectrum biocidal agents against the decline in efficacy of therapeutic agents is provided based on the fitness costs of resistance and the ubiquity of naturally occurring substances that possess antibacterial effect. While the authors conclude from this review of the literature that the incorporation of antibacterial agents into a widening sphere of personal products has had little or no impact on the patterns of microbial susceptibility obsd. in the environment, the assocd. risks remain finite. The use of such products should therefore be assocd. with a clear demonstration of added value either to consumer health or to the product life. Hygienic products should therefore be targeted to applications for which the risks have been established.
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  29. 29
    Jiao, Y.; Niu, L.-n.; Ma, S.; Li, J.; Tay, F. R.; Chen, J.-h. Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance. Prog. Polym. Sci. 2017, 71, 53– 90,  DOI: 10.1016/j.progpolymsci.2017.03.001
    Google Scholar
    29
    Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance
    Jiao, Yang; Niu, Li-na; Ma, Sai; Li, Jing; Tay, Franklin R.; Chen, Ji-hua
    Progress in Polymer Science (2017), 71 (), 53-90CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
    Microbial infections affect humans worldwide. Many quaternary ammonium compds. have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for prepn. of antimicrobial biomaterials. Various polymn. techniques have been employed to prep. antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymn. techniques enable precise control over macromol. structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technol. developments have also been accompanied by potential toxicol. and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-contg. biomaterials that are based on randomized human clin. trials, the golden std. in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.
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  30. 30
    Mei, L.; Lu, Z.; Zhang, X.; Li, C.; Jia, Y. Polymer-Ag Nanocomposites with Enhanced Antimicrobial Activity against Bacterial Infection. ACS Appl. Mater. Interfaces 2014, 6, 15813– 15821,  DOI: 10.1021/am502886m
    Google Scholar
    30
    Polymer-Ag Nanocomposites with Enhanced Antimicrobial Activity against Bacterial Infection
    Mei, Lin; Lu, Zhentan; Zhang, Xinge; Li, Chaoxing; Jia, Yanxia
    ACS Applied Materials & Interfaces (2014), 6 (18), 15813-15821CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Herein, a nontoxic nanocomposite is synthesized by redn. of silver nitrate in the presence of a cationic polymer displaying strong antimicrobial activity against bacterial infection. These nanocomposites with a large concn. of pos. charge promote their adsorption to bacterial membranes through electrostatic interaction. Moreover, the synthesized nanocomposites with polyvalent and synergistic antimicrobial effects can effectively kill both Gram-pos. and Gram-neg. bacteria without the emergence of bacterial resistance. Morphol. changes obtained by transmission electron microscope observation show that these nanocomposites can cause leakage and chaos of intracellular contents. Anal. of the antimicrobial mechanism confirms that the lethal action of nanocomposites against the bacteria started with disruption of the bacterial membrane, subsequent cellular internalization of the nanoparticles, and inhibition of intracellular enzymic activity. This novel antimicrobial material with good cytocompatibility promotes healing of infected wounds in diabetic rats, and has a promising future in the treatment of other infectious diseases.
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  31. 31
    Muñoz-Bonilla, A.; Fernández-García, M. Polymeric materials with antimicrobial activity. Prog. Polym. Sci. 2012, 37, 281– 339,  DOI: 10.1039/978178262499810.1016/j.progpolymsci.2011.08.005
    Google Scholar
    31
    Polymeric materials with antimicrobial activity
    Munoz-Bonilla, Alexandra; Fernandez-Garcia, Marta
    Progress in Polymer Science (2012), 37 (2), 281-339CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
    A review. This article describes the state of the art in the field of antimicrobial polymeric systems during the last decade. Keeping in mind the multitude of existing systems, a classification of the different materials is carried out dividing basically those synthetic polymers that: (a) exhibit antimicrobial activity by themselves; (b) those whose biocidal activity is conferred through their chem. modification; (c) those that incorporate antimicrobial org. compds. with either low or high mol. wt.; and (d) those that involve the addn. of active inorg. systems. This classification is not absolutely unique and in occasions some described polymeric systems could belong to more than one section. However, the purpose of this review is to provide a handy overall vision of the antimicrobial synthetic polymers world.
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  32. 32
    Altay, E.; Yapaöz, M. A.; Keskin, B.; Yucesan, G.; Eren, T. Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP. Colloids Surf., B 2015, 127, 73– 78,  DOI: 10.1016/j.colsurfb.2015.01.020
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    32
    Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP
    Altay, Esra; Yapaoz, Melda Altikatoglu; Keskin, Bahadir; Yucesan, Gundog; Eren, Tarik
    Colloids and Surfaces, B: Biointerfaces (2015), 127 (), 73-78CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
    The purpose of this study is to understand the antibacterial properties of cationic polymers on solid surfaces by investigating the structure-activity relationships. The polymer synthesis was carried via ring opening metathesis polymn. (ROMP) of oxanorbornene derivs. Modulation of mol. wts. and alkyl chain lengths of the polymers were studied to investigate the antibacterial properties on the glass surface. Fluorescein (Na salt) staining contact angle measurements were used to characterize the pos. charge d. and hydrophobicity on the polymer coated surfaces. Pos. charge d. for the surface coated polymers with mol. wts. of 3000 and 10,000 g mol-1 is obsd. to be in the range of 2.3-28.5 nmol cm-2. The ROMP based cationic pyridinium polymer with hexyl unit exhibited the highest bactericidal efficiency against Escherichia coli on solid surface killing 99% of the bacteria in 5 min. However, Ph and octyl functionalized quaternary pyridinium groups exhibited lower biocidal properties on the solid surfaces compared to their soln. phase biocidal properties. Studying the effect of threshold polymer concns. on the antibacterial properties indicated that changing the concns. of polymer coatings on the solid surface dramatically influences antibacterial efficiency.
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  33. 33
    Chen, J.; Peng, H.; Wang, X.; Shao, F.; Yuan, Z.; Han, H. Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation. Nanoscale 2014, 6, 1879– 1889,  DOI: 10.1039/C3NR04941H
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    33
    Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation
    Chen, Juanni; Peng, Hui; Wang, Xiuping; Shao, Feng; Yuan, Zhaodong; Han, Heyou
    Nanoscale (2014), 6 (3), 1879-1889CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
    To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular study was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). GO had a powerful effect on the reprodn. of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range of aggregated graphene oxide sheets, resulting in the local perturbation of their cell membrane and inducing the decrease of the bacterial membrane potential and the leakage of electrolytes of fungal spores. It is likely that GO interacts with the pathogens by mech. wrapping and locally damaging the cell membrane and finally causing cell lysis, which may be one of the major toxicity actions of GO against phytopathogens. The antibacterial mode proposed in this study suggests that the GO may possess antibacterial activity against more multi-resistant bacterial and fungal phytopathogens, and provides useful information about the application of GO in resisting crop diseases.
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  34. 34
    Rasool, K.; Helal, M.; Ali, A.; Ren, C. E.; Gogotsi, Y.; Mahmoud, K. A. Antibacterial Activity of Ti3C2Tx MXene. ACS Nano 2016, 10, 3674– 3684,  DOI: 10.1021/acsnano.6b00181
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    34
    Antibacterial activity of Ti3C2Tx MXene
    Rasool, Kashif; Helal, Mohamed; Ali, Adnan; Ren, Chang E.; Gogotsi, Yury; Mahmoud, Khaled A.
    ACS Nano (2016), 10 (3), 3674-3684CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    MXenes are a family of atomically thin, two-dimensional (2D) transition metal carbides and carbonitrides with many attractive properties. Two-dimensional Ti3C2Tx (MXene) has been recently explored for applications in water desalination/purifn. membranes. A major success indicator for any water treatment membrane is the resistance to biofouling. To validate this and to understand better the health and environmental impacts of the new 2D carbides, the authors investigated the antibacterial properties of single- and few-layer Ti3C2Tx MXene flakes in colloidal soln. The antibacterial properties of Ti3C2Tx were tested against Escherichia coli and Bacillus subtilis by using bacterial growth curves based on optical densities (OD) and colonies growth on agar nutritive plates. Ti3C2Tx shows a greater antibacterial efficiency toward both Gram-neg. E. coli and Gram-pos. B. subtilis compared with graphene oxide (GO), which has been widely reported as an antibacterial agent. Concn.-dependent antibacterial activity was obsd. and more than 98% bacterial cell viability loss was found at 200 μg/mL Ti3C2Tx for both bacterial cells within 4 h of exposure, as confirmed by colony forming unit (CFU) and regrowth curve. An antibacterial mechanism investigation by scanning and transmission electron microscopy coupled with a lactate dehydrogenase release assay indicated damage to the cell membrane, which resulted in release of cytoplasmic materials from the bacterial cells. Reactive oxygen species (ROS) dependent and independent stress induction by Ti3C2Tx was investigated in two sep. abiotic assays. MXenes are expected to be resistant to biofouling and to offer bactericidal properties.
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  35. 35
    Bing, W.; Chen, Z.; Sun, H.; Shi, P.; Gao, N.; Ren, J.; Qu, X. Visible-light-driven enhanced antibacterial and biofilm elimination activity of graphitic carbon nitride by embedded Ag nanoparticles. Nano Res. 2015, 8, 1648– 1658,  DOI: 10.1007/s122710.1007/s12274-014-0654-1
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    35
    Visible-light-driven enhanced antibacterial and biofilm elimination activity of graphitic carbon nitride by embedded Ag nanoparticles
    Bing, Wei; Chen, Zhaowei; Sun, Hanjun; Shi, Peng; Gao, Nao; Ren, Jinsong; Qu, Xiaogang
    Nano Research (2015), 8 (5), 1648-1658CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)
    Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles (NPs) on a semiconductor, since the noble metal NPs act as excellent electron acceptors which inhibit the quick recombination of the photoexcited electron-hole pairs and thereby enhance the generation of reactive oxygen species (ROS). Herein, a highly effective platform, graphitic carbon nitride (g-C3N4) nanosheets with embedded Ag nanoparticles (Ag/g-C3N4), was synthesized by a facile route. Under visible light irradn., the ROS prodn. of Ag/g-C3N4 nanohybrids was greatly improved compared with pristine g-C3N4 nanosheets, and moreover, the nanohybrids showed enhanced antibacterial efficacy and ability to disperse bacterial biofilms. We demonstrate for the first time that the Ag/g-C3N4 nanohybrids are efficient bactericidal agents under visible light irradn., and can also provide a new way for biofilm elimination. The enhanced antibacterial properties and biofilm-disrupting ability of Ag/g-C3N4 nanohybrids may offer many biomedical applications. [Figure not available: see fulltext.].
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  36. 36
    Hou, J.; Miao, L.; Wang, C.; Wang, P.; Ao, Y.; Qian, J.; Dai, S. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes. J. Hazard. Mater. 2014, 276, 164– 170,  DOI: 10.1016/j.jhazmat.2014.04.048
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    36
    Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes
    Hou, Jun; Miao, Lingzhan; Wang, Chao; Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan
    Journal of Hazardous Materials (2014), 276 (), 164-170CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)
    The presence of ZnO NPs in waste streams can neg. affect the efficiency of biol. nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. The temporal and spatial inhibitory effects of ZnO NPs on the O2 respiration activities of aerobic wastewater biofilms were investigated using an O2 microelectrode. The resulting time-course microelectrode measurements demonstrated that ZnO NPs inhibited O2 respiration within 2 h. The spatial distributions of net specific O2 respiration were detd. in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. SEM anal. showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. The inhibition of O2 respiration induced by higher concns. of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissoln. of the ZnO NPs.
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  37. 37
    Fu, F.; Li, L.; Liu, L.; Cai, J.; Zhang, Y.; Zhou, J.; Zhang, L. Construction of Cellulose Based ZnO Nanocomposite Films with Antibacterial Properties through One-Step Coagulation. ACS Appl. Mater. Interfaces 2015, 7, 2597– 2606,  DOI: 10.1021/am507639b
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    37
    Construction of Cellulose Based ZnO Nanocomposite Films with Antibacterial Properties through One-Step Coagulation
    Fu, Feiya; Li, Lingyan; Liu, Lianjie; Cai, Jun; Zhang, Yaping; Zhou, Jinping; Zhang, Lina
    ACS Applied Materials & Interfaces (2015), 7 (4), 2597-2606CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Cellulose based ZnO nanocomposite (RCZ) films were prepd. from cellulose carbamate-NaOH/ZnO solns. through one-step coagulation in Na2SO4 aq. solns. The structure and properties of RCZ films were characterized using XRD, FTIR, XPS, SEM, TEM, TG, tensile testing, and antibacterial activity tests. The content of ZnO in RCZ films was obtained in the range of 2.7-15.1 wt %. ZnO nanoparticles with a hexagonal wurtzite structure agglomerated into large particles, which firmly embedded in the cellulose matrix. RCZ films displayed good mech. properties and high thermal stability. Moreover, the films exhibited excellent UV-blocking properties and antibacterial activities against Staphylococcus aureus and Escherichia coli. A dramatic redn. in viable bacteria was obsd. within 3 h of exposure, while all of the bacteria were killed within 6 h. This work provided a novel and simple pathway for the prepn. of regenerated cellulose films with ZnO nanoparticles for application as functional biomaterials.
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  38. 38
    Hsu, M.-H.; Chang, C.-J. Ag-doped ZnO nanorods coated metal wire meshes as hierarchical photocatalysts with high visible-light driven photoactivity and photostability. J. Hazard. Mater. 2014, 278, 444– 453,  DOI: 10.1016/j.jhazmat.2014.06.038
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    38
    Ag-doped ZnO nanorods coated metal wire meshes as hierarchical photocatalysts with high visible-light driven photoactivity and photostability
    Hsu, Mu-Hsiang; Chang, Chi-Jung
    Journal of Hazardous Materials (2014), 278 (), 444-453CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)
    Ag-doped ZnO nanorods were grown on stainless-steel wire meshes to fabricate the hierarchical photocatalysts with excellent visible light driven activity and anti-photocorrosion property. Effects of Ag doping and the surface structure on the surface chem., surface wetting properties, absorption band shift, photoelectrochem. response, and photocatalytic decolorization properties of the hierarchical photocatalysts, together with the stability of photocatalytic activity for recycled photocatalysts were investigated. Ag doping leads to red-shift in the absorption band and increased visible light absorption. Nanorods coated wire meshes hierarchical structure not only increases the surface area of photocatalysts but also makes the surface hydrophilic. The photocatalytic activity enhancement and reduced photocorrosion can be achieved because of increased surface area, enhanced hydrophilicity, and the interaction between the metal wire/ZnO and Ag/ZnO heterostructure interface which can improve the charge sepn. of photogenerated charge carriers.
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  39. 39
    Jian, H.-J.; Wu, R.-S.; Lin, T.-Y.; Li, Y.-J.; Lin, H.-J.; Harroun, S. G.; Lai, J.-Y.; Huang, C.-C. Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis. ACS Nano 2017, 11, 6703– 6716,  DOI: 10.1021/acsnano.7b01023
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    39
    Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis
    Jian, Hong-Jyuan; Wu, Ren-Siang; Lin, Tzu-Yu; Li, Yu-Jia; Lin, Han-Jia; Harroun, Scott G.; Lai, Jui-Yang; Huang, Chih-Ching
    ACS Nano (2017), 11 (7), 6703-6716CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    We have developed a one-step method to synthesize carbon quantum dots (CQDPAs) from biogenic polyamines (PAs) as an antibacterial agent for topical treatment of bacterial keratitis (BK). CQDs synthesized by direct pyrolysis of spermidine (Spd) powder through a simple dry heating treatment exhibit a soly. and yield much higher than those from putrescine and spermine. We demonstrate that CQDs obtained from Spds (CQDSpds) possess effective antibacterial activities against non-multidrug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica serovar Enteritidis bacteria and also against the multidrug-resistant bacteria, methicillin-resistant S. aureus. The minimal inhibitory concn. (MIC) of CQDSpds is ∼2500-fold lower than that of spermidine alone, demonstrating their strong antibacterial capabilities. Investigation of the possible mechanisms behind the antibacterial activities of the as-synthesized CQDSpds indicates that the super-cationic CQDSpds with small size (diam. ca. 6 nm) and highly pos. charge (ζ-potential ca. +45 mV) cause severe disruption of the bacterial membrane. In vitro cytotoxicity, hemolysis, hemagglutination, genotoxicity, and oxidative stress and in vivo morphol. and physiol. cornea change evaluations show the good biocompatibility of CQDSpds. Furthermore, topical ocular administration of CQDSpds can induce the opening of the tight junction of corneal epithelial cells, thereby leading to great antibacterial treatment of S. aureus-induced BK in rabbits. Our results suggest that CQDSpds are a promising antibacterial candidate for clin. applications in treating eye-related bacterial infections and even persistent bacteria-induced infections.
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  40. 40
    Yuan, H.; Liu, Z.; Liu, L.; Lv, F.; Wang, Y.; Wang, S. Cationic conjugated polymers for discrimination of microbial pathogens. Adv. Mater. 2014, 26, 4333– 4338,  DOI: 10.1002/adma.201400636
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    40
    Cationic Conjugated Polymers for Discrimination of Microbial Pathogens
    Yuan, Huanxiang; Liu, Zhang; Liu, Libing; Lv, Fengting; Wang, Yilin; Wang, Shu
    Advanced Materials (Weinheim, Germany) (2014), 26 (25), 4333-4338CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A cationic poly(p-phenylene vinylene) (PPV-NMe3+) has been synthesized for rapid and simple discrimination of fungi, Gram-pos., and Gram-neg. bacteria. The thermodynamical and the zeta potential measurements exhibit that the binding of PPV-NMe3+ to Candida albicans and Escherichia coli is dominated by electrostatic interactions, while hydrophobic interactions for PPV-NMe3+ and Bacillus subtilis. Single self-luminous PPV-NMe3+ mols. could discriminate fungi, Gram-pos. bacteria, and Gram-neg. bacteria under a fluorescence microscope only via varying the ion strengths of the buffer soln. in a rapid and simple way. There are several unique features for the authors' new assay system. First, the method is rapid. It takes only <3 h to complete the anal. including culturing, detecting, and discriminating the pathogens. Second, the method is much simpler than other assays (such as PCR). Direct discrimination by the fluorescence intensity under a fluorescence microscope is the most important characteristic of the assay. Third, this method can be applied to complicated situations in which the targets consist of two or three classes of microorganisms (fungi, Gram-pos. bacteria, and Gram-neg. bacteria). Thus cationic conjugated polymers exhibit high potential as diagnostic materials for the detection and discrimination of pathogens.
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  41. 41
    Zhu, C.; Yang, Q.; Lv, F.; Liu, L.; Wang, S. Conjugated Polymer-Coated Bacteria for Multimodal Intracellular and Extracellular Anticancer Activity. Adv. Mater. 2013, 25, 1203– 1208,  DOI: 10.1002/adma.201204550
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    41
    Conjugated Polymer-Coated Bacteria for Multimodal Intracellular and Extracellular Anticancer Activity
    Zhu, Chunlei; Yang, Qiong; Lv, Fengting; Liu, Libing; Wang, Shu
    Advanced Materials (Weinheim, Germany) (2013), 25 (8), 1203-1208CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
    We developed a bacterial vector-based drug loading, delivery and release system for multimodal anticancer activity. The loaded drug is polypeptide exotoxin A of Pseudomonas aeruginosa (PE66). We first constructed a toxin-expressing plasmid pET28a-PE66 and subsequently installed it into the expression vector BL21 to fabricate the bacterial micro-/nanovectors. A conjugated polyelectrolyte (CP) could be used for coating E. coli by electrostatic and hydrophobic interactions. Facilitated by the collaborative release effect caused by CP and membrane- disrupting antibiotic polymyxin B, the loaded toxin PE66 can considerably leak out from the capsules and exert their toxic functions on cancer cells to initiate programmed cell apoptosis.
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  42. 42
    Wang, G.; Jin, W.; Qasim, A. M.; Gao, A.; Peng, X.; Li, W.; Feng, H.; Chu, P. K. Antibacterial effects of titanium embedded with silver nanoparticles based on electron-transfer-induced reactive oxygen species. Biomaterials 2017, 124, 25– 34,  DOI: 10.1016/j.biomaterials.2017.01.028
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    42
    Antibacterial effects of titanium embedded with silver nanoparticles based on electron-transfer-induced reactive oxygen species
    Wang, Guomin; Jin, Weihong; Qasim, Abdul Mateen; Gao, Ang; Peng, Xiang; Li, Wan; Feng, Hongqing; Chu, Paul K.
    Biomaterials (2017), 124 (), 25-34CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
    Although titanium embedded with silver nanoparticles (Ag-NPs@Ti) are suitable for biomedical implants because of the good cytocompatibility and antibacterial characteristics, the exact antibacterial mechanism is not well understood. In the present work, the antibacterial mechanisms of Ag-NPs@Ti prepd. by plasma immersion ion implantation (PIII) are explored in details. The antibacterial effects of the Ag-NPs depend on the cond. of the substrate revealing the importance of electron transfer in the antibacterial process. In addn., electron transfer between the Ag-NPs and titanium substrate produces bursts of reactive oxygen species (ROS) in both the bacteria cells and culture medium. ROS leads to bacteria death by inducing intracellular oxidn., membrane potential variation, and cellular contents release and the antibacterial ability of Ag-NPs@Ti is inhibited appreciably after adding ROS scavengers. Even though ROS signals are detected from osteoblasts cultured on Ag-NPs@Ti, the cell compatibility is not impaired. This electron-transfer-based antibacterial process which produces ROS provides insights into the design of biomaterials with both antibacterial properties and cytocompatibility.
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  43. 43
    Courtney, C. M.; Goodman, S. M.; McDaniel, J. A.; Madinger, N. E.; Chatterjee, A.; Nagpal, P. Photoexcited quantum dots for killing multidrug-resistant bacteria. Nat. Mater. 2016, 15, 529– 534,  DOI: 10.1038/nmat4542
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    43
    Photoexcited quantum dots for killing multidrug-resistant bacteria
    Courtney, Colleen M.; Goodman, Samuel M.; McDaniel, Jessica A.; Madinger, Nancy E.; Chatterjee, Anushree; Nagpal, Prashant
    Nature Materials (2016), 15 (5), 529-534CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
    Multidrug-resistant bacterial infections are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Metal nanoparticles can induce cell death, yet the toxicity effect is typically nonspecific. Here, we show that photoexcited quantum dots (QDs) can kill a wide range of multidrug-resistant bacterial clin. isolates, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Salmonella typhimurium. The killing effect is independent of material and controlled by the redox potentials of the photogenerated charge carriers, which selectively alter the cellular redox state. We also show that the QDs can be tailored to kill 92% of bacterial cells in a monoculture, and in a co-culture of E. coli and HEK 293T cells, while leaving the mammalian cells intact, or to increase bacterial proliferation. Photoexcited QDs could be used in the study of the effect of redox states on living systems, and lead to clin. phototherapy for the treatment of infections.
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  44. 44
    Cabiscol, E.; Tamarit, J.; Ros, J. Oxidative stress in bacteria and protein damage by reactive oxygen species. Int. Microbiol. 2000, 3, 3– 8
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    44
    Oxidative stress in bacteria and protein damage by reactive oxygen species
    Cabiscol, Elisa; Tamarit, Jordi; Ros, Joaquim
    International Microbiology (2000), 3 (1), 3-8CODEN: INMIFW; ISSN:1139-6709. (Springer-Verlag Iberica)
    A review with 50 refs. The advent of O2 in the atm. was among the first major pollution events that occurred on earth. The reaction between ferrous iron, very abundant in the reductive early atm., and oxygen results in the formation of harmful superoxide and hydroxyl radicals, which affect all macromols. (DNA, lipids and proteins). Living organisms have to build up mechanisms to protect themselves against oxidative stress, with enzymes such as catalase and superoxide dismutase, small proteins like thioredoxin and glutaredoxin, and mols. such as glutathione. Bacterial genetic responses to oxidative stress are controlled by two major transcriptional regulators (OxyR and SoxRS). This paper reviews major key points in the generation of reactive oxygen species in bacteria, defense mechanisms and genetic responses to oxidative stress. Special attention is paid to the oxidative damage to proteins.
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    PMID: 10963327.

  45. 45
    Blokhina, O.; Virolainen, E.; Fagerstedt, K. V. Antioxidants, oxidative damage and oxygen deprivation stress: a review. Ann. Bot. 2003, 91, 179– 194,  DOI: 10.1093/aob/mcf118
    Google Scholar
    45
    Antioxidants, oxidative damage and oxygen deprivation stress: A review
    Blokhina, Olga; Virolainen, Eija; Fagerstedt, Kurt V.
    Annals of Botany (Oxford, United Kingdom) (2003), 91 (Spec. Issue), 179-194CODEN: ANBOA4; ISSN:0305-7364. (Oxford University Press)
    A review. Oxidative stress is induced by a wide range of environmental factors including UV stress, pathogen invasion (hypersensitive reaction), herbicide action and oxygen shortage. Oxygen deprivation stress in plant cells is distinguished by three physiol. different states: transient hypoxia anoxia and reoxygenation. Generation of reactive oxygen species (ROS) is characteristic for hypoxia and esp. for reoxygenation. Of the ROS, hydrogen peroxide (H2O2) and superoxide (O2.-) are both produced in a no. of cellular reactions, including the iron-catalyzed Fenton reaction, and by various enzymes such as lipoxygenases, peroxidases, NADPH oxidase and xanthine oxidase. The main cellular components susceptible to damage by free radicals are lipids (peroxidn. of unsatd. fatty acids in membranes), proteins (denaturation), carbohydrates and nucleic acids. Consequences of hypoxia-induced oxidative stress depend on tissue and/or species (i.e. their tolerance to anoxia), on membrane properties, on endogenous antioxidant content and on the ability to induce the response in the antioxidant system. Effective utilization of energy resources (starch, sugars) and the switch to anaerobic metab. and the preservation of the redox status of the cell are vital for survival. The formation of ROS is prevented by an antioxidant system: low mol. mass antioxidants (ascorbic acid, glutathione, tocopherols), enzymes regenerating the reduced forms of antioxidants, and ROS-interacting enzymes such as SOD, peroxidases and catalases. In plant tissues many phenolic compds. (in addn. to tocopherols) are potential antioxidants: flavonoids, tannins and lignin precursors may work as ROS-scavenging compds. Antioxidants act as a cooperative network, employing a series of redox reactions. Interactions between ascorbic acid and glutathione, and ascorbic acid and phenolic compds. are well known. Under oxygen deprivation stress some contradictory results on the antioxidant status have been obtained. Expts. on overexpression of antioxidant prodn. do not always result in the enhancement of the antioxidative defense, and hence increased antioxidative capacity does not always correlate pos. with the degree of protection. Here, the authors present a consideration of factors which possibly affect the effectiveness of antioxidant protection under oxygen deprivation as well as under other environmental stresses. Such aspects as compartmentalization of ROS formation and antioxidant localization, synthesis and transport of antioxidants, the ability to induce the antioxidant defense and cooperation (and/or compensation) between different antioxidant systems are the determinants of the competence of the antioxidant system.
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  46. 46
    Tehrani-Bagha, A. R.; Kärnbratt, J.; Löfroth, J.-E.; Holmberg, K. Cationic ester-containing gemini surfactants: Determination of aggregation numbers by time-resolved fluorescence quenching. J. Colloid Interface Sci. 2012, 376, 126– 132,  DOI: 10.1016/j.jcis.2012.02.053
    Google Scholar
    46
    Cationic ester-containing gemini surfactants: Determination of aggregation numbers by time-resolved fluorescence quenching
    Tehrani-Bagha, A. R.; Kaernbratt, J.; Loefroth, J.-E.; Holmberg, K.
    Journal of Colloid and Interface Science (2012), 376 (1), 126-132CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
    The micellar aggregation no. of a series of ester-contg. gemini surfactants was detd. with steady state and with time-resolved fluorescence quenching. The latter method gave values of aggregation no. about twice those obtained with the former method. The length of the spacer was the most important factor affecting the aggregation no. The length and the nature of the surfactant alkyl chains were of less importance in spite of the fact that the length of the alkyl chains strongly affects the soln. properties of the unimers.
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  47. 47
    Rasool, K.; Helal, M.; Ali, A.; Ren, C. E.; Gogotsi, Y.; Mahmoud, K. A. Antibacterial Activity of Ti3C2T x MXene. ACS Nano 2016, 10, 3674– 3684,  DOI: 10.1021/acsnano.6b00181
    Google Scholar
    47
    Antibacterial activity of Ti3C2Tx MXene
    Rasool, Kashif; Helal, Mohamed; Ali, Adnan; Ren, Chang E.; Gogotsi, Yury; Mahmoud, Khaled A.
    ACS Nano (2016), 10 (3), 3674-3684CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    MXenes are a family of atomically thin, two-dimensional (2D) transition metal carbides and carbonitrides with many attractive properties. Two-dimensional Ti3C2Tx (MXene) has been recently explored for applications in water desalination/purifn. membranes. A major success indicator for any water treatment membrane is the resistance to biofouling. To validate this and to understand better the health and environmental impacts of the new 2D carbides, the authors investigated the antibacterial properties of single- and few-layer Ti3C2Tx MXene flakes in colloidal soln. The antibacterial properties of Ti3C2Tx were tested against Escherichia coli and Bacillus subtilis by using bacterial growth curves based on optical densities (OD) and colonies growth on agar nutritive plates. Ti3C2Tx shows a greater antibacterial efficiency toward both Gram-neg. E. coli and Gram-pos. B. subtilis compared with graphene oxide (GO), which has been widely reported as an antibacterial agent. Concn.-dependent antibacterial activity was obsd. and more than 98% bacterial cell viability loss was found at 200 μg/mL Ti3C2Tx for both bacterial cells within 4 h of exposure, as confirmed by colony forming unit (CFU) and regrowth curve. An antibacterial mechanism investigation by scanning and transmission electron microscopy coupled with a lactate dehydrogenase release assay indicated damage to the cell membrane, which resulted in release of cytoplasmic materials from the bacterial cells. Reactive oxygen species (ROS) dependent and independent stress induction by Ti3C2Tx was investigated in two sep. abiotic assays. MXenes are expected to be resistant to biofouling and to offer bactericidal properties.
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  • Abstract

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    Figure 1

    Figure 1. Characterization of BQAS by FT-IR spectroscopy (A) and 1H NMR (B).

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    Figure 2

    Figure 2. Growth curves of (A) E. coli and (B) S. aureus in LB medium at 30 °C after the bacterial cells (200 μL, 108 cfu/mL) were treated with different concentrations of BQAS. Colony count assay of (C) E. coli and (D) S. aureus bacterial cells treated separately with (a) 0, (b) 12.5, (c) 25, (d) 50, (e) 100, and (f) 200 μg/mL of BQAS.

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    Figure 3

    Figure 3. Cell death rates of (A) E. coli and (B) S. aureus after incubation with BQAS and CTAB dispersions at different concentrations (0–200 μg/mL) for 3 h at 30 °C. E. coli and S. aureus untreated with BQAS or CTAB were used as control. Error bars represent the standard deviation.

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    Figure 4

    Figure 4. Fluorescence microscopic images of E. coli (top panel) and S. aureus (bottom panel) (cells stained with PI and DAPI) after exposure to BQAS at concentrations of (A) 0, (B) 12.5, (C) 25, (D) 50, (E) 100, and (F) 200 μg/mL, respectively.

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    Figure 5

    Figure 5. SEM images of E. coli (A,B) and S. aureus (C,D), untreated with BQAS (A,C) and treated with BQAS (B,D). A 200 μL of BQAS (200 μg/mL) was incubated with 200 μL of bacterial dispersion (108 cfu/mL) for 3 h at a shaking speed of 120 rpm at 30 °C.

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    Figure 6

    Figure 6. TEM images of E. coli (A,B) and S. aureus (C,D), untreated with BQAS (A,C) and treated with BQAS (B,D). A 200 μL of BQAS (200 μL/mL) was incubated with 200 μL of bacterial dispersion (108 cfu/mL) for 3 h at a shaking speed of 120 rpm at 30 °C.

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    Figure 7

    Figure 7. (A) BQAS cytotoxicity measured by the LDH release from the bacterial cells after treatment with different concentrations (0–200 μg/mL) of BQAS for 3 h. (B) Release of protein from bacteria treated with BQAS (0–200 μg/mL). Bacterial cells (108 cfu/mL) incubated with 200 μL of different concentrations (0–200 μg/mL) of BQAS at 30 °C for 3 h at a shaking speed of 120 rpm. Error bars represent the standard deviation (n = 3).

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    Figure 8

    Figure 8. (A) Zeta potential of BQAS in the absence and presence of BSA and (B) death rate of S. aureus and E. coli for the treatments of BQAS in the absence and presence of BSA. Error bars represent the standard deviation of three repeated measurements.

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    Figure 9

    Figure 9. ESR spectra of (A) DMPO-•OH and (B) DMPO-•O2– for BQAS.

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    Figure 10

    Figure 10. Intracellular ROS staining results of E. coli (A–C) and S. aureus (D–F) bacterial cells after treatment with (A) 0, (B) 50, and (C) 200 μg/mL of BQAS, respectively. Bacterial suspensions in deionized water without BQAS were used as control.

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  • References

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    This article references 47 other publications.

    1. 1
      Subbiahdoss, G.; Sharifi, S.; Grijpma, D. W.; Laurent, S.; van der Mei, H. C.; Mahmoudi, M.; Busscher, H. J. Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci. Acta Biomater. 2012, 8, 2047– 2055,  DOI: 10.1016/j.actbio.2012.03.002
      1
      Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci
      Subbiahdoss, Guruprakash; Sharifi, Shahriar; Grijpma, Dirk W.; Laurent, Sophie; van der Mei, Henny C.; Mahmoudi, Morteza; Busscher, Henk J.
      Acta Biomaterialia (2012), 8 (6), 2047-2055CODEN: ABCICB; ISSN:1742-7061. (Elsevier Ltd.)
      Biofilms on biomaterial implants are hard to eradicate with antibiotics due to the protection offered by the biofilm mode of growth, esp. when caused by antibiotic-resistant strains. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as targeted drug delivery and magnetic resonance imaging. Here, we evaluate the hypothesis that SPIONs can be effective in the treatment of biomaterial-assocd. infection. SPIONs can be targeted to the infection site using an external magnetic field, causing deep penetration in a biofilm and possibly effectiveness against antibiotic-resistant strains. We report that carboxyl-grafted SPIONs, magnetically concd. in a biofilm, cause an approx. 8-fold higher percentage of dead staphylococci than does gentamicin for a gentamicin-resistant strain in a developing biofilm. Moreover, magnetically concd. carboxyl-grafted SPIONs cause bacterial killing in an established biofilm. Thus magnetic targeting of SPIONs constitutes a promising alternative for the treatment of costly and recalcitrant biomaterial-assocd. infections by antibiotic-resistant strains.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmsVGrs7s%253D&md5=e457413da27734edd45e5ab1a9ba9e4e
    2. 2
      Rizzello, L.; Pompa, P. P. Nanosilver-based antibacterial drugs and devices: mechanisms, methodological drawbacks, and guidelines. Chem. Soc. Rev. 2014, 43, 1501– 1518,  DOI: 10.1039/c3cs60218d
      2
      Nanosilver-based antibacterial drugs and devices: Mechanisms, methodological drawbacks, and guidelines
      Rizzello, Loris; Pompa, Pier Paolo
      Chemical Society Reviews (2014), 43 (5), 1501-1518CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      Despite the current advancement in drug discovery and pharmaceutical biotechnol., infection diseases induced by bacteria continue to be one of the greatest health problems worldwide, afflicting millions of people annually. Almost all microorganisms have, in fact, an intrinsic outstanding ability to flout many therapeutic interventions, thanks to their fast and easy-to-occur evolutionary genetic mechanisms. At the same time, big pharmaceutical companies are losing interest in new antibiotics development, shifting their capital investments in much more profitable research and development fields. New smart solns. are, thus, required to overcome such concerns, and should combine the feasibility of industrial prodn. processes with cheapness and effectiveness. In this framework, nanotechnol.-based solns., and in particular silver nanoparticles (AgNPs), have recently emerged as promising candidates in the market as new antibacterial agents. AgNPs display, in fact, enhanced broad-range antibacterial/antiviral properties, and their synthesis procedures are quite cost effective. However, despite their increasing impact on the market, many relevant issues are still open. These include the mol. mechanisms governing the AgNPs-bacteria interactions, the physico-chem. parameters underlying their toxicity to prokaryotes, the lack of standardized methods and materials, and the uncertainty in the definition of general strategies to develop smart antibacterial drugs and devices based on nanosilver. In this review, we analyze the exptl. data on the bactericidal effects of AgNPs, discussing the complex scenario and presenting the potential drawbacks and limitations in the techniques and methods employed. Moreover, after analyzing in depth the main mechanisms involved, we provide some general strategies/procedures to perform antibacterial tests of AgNPs, and propose some general guidelines for the design of antibacterial nanosystems and devices based on silver/nanosilver.
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    3. 3
      Liu, C.; Xie, X.; Zhao, W.; Liu, N.; Maraccini, P. A.; Sassoubre, L. M.; Boehm, A. B.; Cui, Y. Conducting Nanosponge Electroporation for Affordable and High-Efficiency Disinfection of Bacteria and Viruses in Water. Nano Lett. 2013, 13, 4288– 4293,  DOI: 10.1021/nl402053z
      3
      Conducting nanosponge electroporation for affordable and high-efficiency disinfection of bacteria and viruses in water
      Liu, Chong; Xie, Xing; Zhao, Wenting; Liu, Nian; Maraccini, Peter A.; Sassoubre, Lauren M.; Boehm, Alexandria B.; Cui, Yi
      Nano Letters (2013), 13 (9), 4288-4293CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      High-efficiency, affordable, and low energy water disinfection methods are in great need to prevent diarrheal illness, which is one of the top five leading causes of death over the world. Traditional water disinfection methods have drawbacks including carcinogenic disinfection byproducts formation, energy and time intensiveness, and pathogen recovery. Here, we report an innovative method that achieves high-efficiency water disinfection by introducing nanomaterial-assisted electroporation implemented by a conducting nanosponge filtration device. The use of one-dimensional (1D) nanomaterials allows electroporation to occur at only several volts, which is 2 to 3 orders of magnitude lower than that in traditional electroporation applications. The disinfection mechanism of electroporation prevents harmful byproduct formation and ensures a fast treatment speed of 15,000 L/(h·m2), which is equal to a contact time of 1 s. The conducting nanosponge made from low-cost polyurethane sponge coated with carbon nanotubes and silver nanowires ensures the device's affordability. This method achieves more than 6 log (99.9999%) removal of four model bacteria, including Escherichia coli, Salmonella enterica typhimirium, Enterococcus faecalis, and Bacillus subtilis, and more than 2 log (99%) removal of one model virus, bacteriophage MS2, with a low energy consumption of only 100 J/L.
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    4. 4
      Fischbach, M. A.; Walsh, C. T. Antibiotics for Emerging Pathogens. Science 2009, 325, 1089– 1093,  DOI: 10.1126/science.1176667
      4
      Antibiotics for Emerging Pathogens
      Fischbach, Michael A.; Walsh, Christopher T.
      Science (Washington, DC, United States) (2009), 325 (5944), 1089-1093CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      A review. Antibiotic-resistant strains of pathogenic bacteria are increasingly prevalent in hospitals and the community. New antibiotics are needed to combat these bacterial pathogens, but progress in developing them has been slow. Historically, most antibiotics have come from a small set of mol. scaffolds whose functional lifetimes have been extended by generations of synthetic tailoring. The emergence of multidrug resistance among the latest generation of pathogens suggests that the discovery of new scaffolds should be a priority. Promising approaches to scaffold discovery are emerging; they include mining underexplored microbial niches for natural products, designing screens that avoid rediscovering old scaffolds, and repurposing libraries of synthetic mols. for use as antibiotics.
      >> More from SciFinder ®
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    5. 5
      Shirley, D.; Chrom, C. L.; Caputo, G. A. Membrane Binding and Antimicrobial Activity of a Catioinc, Porphyrin-Binding Peptide. Biophys. J. 2017, 112, 380a,  DOI: 10.1016/j.bpj.2016.11.2066
      There is no corresponding record for this reference.
    6. 6
      Li, P.; Poon, Y. F.; Li, W.; Zhu, H.-Y.; Yeap, S. H.; Cao, Y.; Qi, X.; Zhou, C.; Lamrani, M.; Beuerman, R. W.; Kang, E.-T.; Mu, Y.; Li, C. M.; Chang, M. W.; Leong, S. S. J.; Chan-Park, M. B. A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability. Nat. Mater. 2011, 10, 149– 156,  DOI: 10.1038/nmat2915
      6
      A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability
      Li, Peng; Poon, Yin Fun; Li, Weifeng; Zhu, Hong-Yuan; Yeap, Siew Hooi; Cao, Ye; Qi, Xiaobao; Zhou, Chuncai; Lamrani, Mouad; Beuerman, Roger W.; Kang, En-Tang; Mu, Yuguang; Li, Chang Ming; Chang, Matthew W.; Leong, Susanna Su Jan; Chan-Park, Mary B.
      Nature Materials (2011), 10 (2), 149-156CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      Despite advanced sterilization and aseptic techniques, infections assocd. with medical implants have not been eradicated. Most present coatings cannot simultaneously fulfil the requirements of antibacterial and antifungal activity as well as biocompatibility and reusability. Here, we report an antimicrobial hydrogel based on dimethyldecylammonium chitosan (with high quaternization)-graft-poly(ethylene glycol) methacrylate (DMDC-Q-g-EM) and poly(ethylene glycol) diacrylate, which has excellent antimicrobial efficacy against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Fusarium solani. The proposed mechanism of the antimicrobial activity of the polycationic hydrogel is by attraction of sections of anionic microbial membrane into the internal nanopores of the hydrogel, like an 'anion sponge', leading to microbial membrane disruption and then microbe death. We have also demonstrated a thin uniform adherent coating of the hydrogel by simple UV immobilization. An animal study shows that DMDC-Q-g-EM hydrogel coating is biocompatible with rabbit conjunctiva and has no toxicity to the epithelial cells or the underlying stroma.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXovV2isQ%253D%253D&md5=18b8c0d55f18af86bd3e5de9d4a9dadd
    7. 7
      Kang, S.; Pinault, M.; Pfefferle, L. D.; Elimelech, M. Single-walled carbon nanotubes exhibit strong antimicrobial activity. Langmuir 2007, 23, 8670– 8673,  DOI: 10.1021/la701067r
      7
      Single-Walled Carbon Nanotubes Exhibit Strong Antimicrobial Activity
      Kang, Seoktae; Pinault, Mathieu; Pfefferle, Lisa D.; Elimelech, Menachem
      Langmuir (2007), 23 (17), 8670-8673CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      The authors provide the first direct evidence that highly purified single-walled carbon nanotubes (SWNTs) exhibit strong antimicrobial activity. By using a pristine SWNT with a narrow diam. distribution, the authors demonstrate that cell membrane damage resulting from direct contact with SWNT aggregates is the likely mechanism leading to bacterial cell death. This finding may be useful in the application of SWNTs as building blocks for antimicrobial materials.
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    8. 8
      Wang, X.; Liu, X.; Han, H. Evaluation of antibacterial effects of carbon nanomaterials against copper-resistant Ralstonia solanacearum. Colloids Surf., B 2013, 103, 136– 142,  DOI: 10.1016/j.colsurfb.2012.09.044
      8
      Evaluation of antibacterial effects of carbon nanomaterials against copper-resistant Ralstonia solanacearum
      Wang, Xiuping; Liu, Xueqin; Han, Heyou
      Colloids and Surfaces, B: Biointerfaces (2013), 103 (), 136-142CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
      The authors investigated the antibacterial activity and the action mode of carbon nanomaterials (CNMs) against the copper-resistant plant pathogenic bacterium Ralstonia solanacearum (R. solanacearum). Single-walled carbon nanotubes (SWCNTs) dispersion was found to show the strongest antibacterial activity, sequentially followed by graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO) and fullerene (C60). This investigation of the antibacterial mechanism of SWCNTs and GO indicated that the damage to the cell membrane leads to the release of cytoplasm materials from the bacterium, which is the causative factor for the inactivation of R. solanacearum bacterial cells. The superior antibacterial effect, and the novel antibacterial mode of SWCNTs and GO suggest that those carbon nanomaterials may have important applications in the control of plant bacterial diseases.
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    9. 9
      Liu, S.; Zeng, T. H.; Hofmann, M.; Burcombe, E.; Wei, J.; Jiang, R.; Kong, J.; Chen, Y. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress. ACS Nano 2011, 5, 6971– 6980,  DOI: 10.1021/nn202451x
      9
      Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: Membrane and oxidative stress
      Liu, Shao-Bin; Zeng, Ting-Ying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rong-Rong; Kong, Jing; Chen, Yuan
      ACS Nano (2011), 5 (9), 6971-6980CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model: Escherichia coli. Under similar concn. and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest av. size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O2·-) induced reactive oxygen species (ROS) prodn. is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidn. capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidn. stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidn. The authors envision that physicochem. properties of graphene-based materials, such as d. of functional groups, size, and cond., can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials.
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    10. 10
      Ivankin, A.; Livne, L.; Mor, A.; Caputo, G. A.; DeGrado, W. F.; Meron, M.; Lin, B.; Gidalevitz, D. Role of the conformational rigidity in the design of biomimetic antimicrobial compounds. Angew. Chem., Int. Ed. 2010, 49, 8462– 8465,  DOI: 10.1002/anie.201003104
      10
      Role of the Conformational Rigidity in the Design of Biomimetic Antimicrobial Compounds
      Ivankin, Andrey; Livne, Liran; Mor, Amram; Caputo, Gregory A.; DeGrado, William F.; Meron, Mati; Lin, Binhua; Gidalevitz, David
      Angewandte Chemie, International Edition (2010), 49 (45), 8462-8465, S8462/1-S8462/3CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Antimicrobial peptides (AMPs) are naturally occurring antibiotics found in essentially all living organisms. In the past two decades, AMPs have attracted considerable interest because of their potential therapeutic use as antiinfective agents. There exists, however, a no. of serious challenges preventing AMP from reaching a pharmaceutical market including their rapid in vivo degrdn., high prodn. costs, and reduced activity in physiol. conditions. Efforts to overcome these problems while retaining the peptides' natural antiinfective properties resulted in the emergence of a rapidly expanding field of nonnatural mimics of antimicrobial peptides. Good understanding of the structure-activity relationships in AMPs is essential in the effort to create a successful peptidomimetic compd. The authors have reported results of the first X-ray study of interactions between nonnatural AMP mimics and model bacterial membranes aimed at understanding the role of structural flexibility on the activity of antimicrobials. The results show that conformational flexibility does not prevent antimicrobials from exerting a strong membrane-disruptive activity. In addn., we have demonstrated that while penetration of lipid A represents a serious challenge for the conformationally rigid antimicrobials, the flexible OAK-I incorporates into lipid A with the same propensity as into DPPG. This implies that the structured and flexible antimicrobials act on the bacterial outer membrane differently. In recent years, a no. of novel synthetic oligomers and linear polymers with favorable antimicrobial efficacy, yet no specific or regular conformation, have been identified. Our results will aid in the rational design and optimization of emerging and future nonnatural antimicrobial agents.
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    11. 11
      Ghosh, C.; Manjunath, G. B.; Akkapeddi, P.; Yarlagadda, V.; Hoque, J.; Uppu, D. S. S. M.; Konai, M. M.; Haldar, J. Small molecular antibacterial peptoid mimics: the simpler the better!. J. Med. Chem. 2014, 57, 1428– 1436,  DOI: 10.1021/jm401680a
      11
      Small molecular antibacterial peptoid mimics: the simpler the better!
      Ghosh, Chandradhish; Manjunath, Goutham B.; Akkapeddi, Padma; Yarlagadda, Venkateswarlu; Hoque, Jiaul; Uppu, Divakara S. S. M.; Konai, Mohini M.; Haldar, Jayanta
      Journal of Medicinal Chemistry (2014), 57 (4), 1428-1436CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)
      The emergence of multidrug-resistant bacteria compounded by the depleting arsenal of antibiotics has accelerated efforts toward development of antibiotics with novel mechanisms of action. The authors present a series of small mol. antibacterial peptoid mimics which exhibit high in vitro potency against a variety of Gram-pos. and Gram-neg. bacteria, including drug-resistant species such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. The highlight of these compds. is their superior activity against the major nosocomial pathogen Pseudomonas aeruginosa. Nontoxic toward mammalian cells, these rapidly bactericidal compds. primarily act by permeabilization and depolarization of bacterial membrane. Synthetically simple and selectively antibacterial, these compds. can be developed into a newer class of therapeutic agents against multidrug resistant bacterial species.
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    12. 12
      Niu, Y.; Wang, M.; Cao, Y.; Nimmagadda, A.; Hu, J.; Wu, Y.; Cai, J.; Ye, X.-S. Rational Design of Dimeric Lysine N-Alkylamides as Potent and Broad-Spectrum Antibacterial Agents. J. Med. Chem. 2018, 61, 2865– 2874,  DOI: 10.1021/acs.jmedchem.7b01704
      12
      Rational design of dimeric lysine N-alkylamides as potent and broad-spectrum antibacterial agents
      Niu, Youhong; Wang, Minghui; Cao, Yafei; Nimmagadda, Alekhya; Hu, Jianxing; Wu, Yanfen; Cai, Jianfeng; Ye, Xin-Shan
      Journal of Medicinal Chemistry (2018), 61 (7), 2865-2874CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)
      Antibiotic resistance is one of the biggest threats to public health, and new antibacterial agents hence are in an urgent need to combat infectious diseases caused by multidrug-resistant (MDR) pathogens. Utilizing dimerization strategy, we rationally designed and efficiently synthesized a new series of small mol. dimeric lysine alkylamides as mimics of AMPs. Evaluation of these mimics against a panel of Gram-pos. and Gram-neg. bacteria including MDR strains was performed, and a broad-spectrum and potent compd. 3d was identified. This compd. displayed high specificity toward bacteria over mammalian cell. Time-kill kinetics and mechanistic studies suggest that compd. 3d quickly eliminated bacteria in a bactericidal mode by disrupting bacterial cell membrane. In addn., lead compd. 3d could inhibit biofilm formation and did not develop drug resistance in S. aureus and E. coli over 14 passages. These results suggested that dimeric lysine nonylamide has immense potential as a new type of novel small mol. agent to combat antibiotic resistance.
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    13. 13
      Tew, G. N.; Scott, R. W.; Klein, M. L.; DeGrado, W. F. De novo design of antimicrobial polymers, foldamers, and small molecules: from discovery to practical applications. Acc. Chem. Res. 2010, 43, 30– 39,  DOI: 10.1021/ar900036b
      13
      De Novo Design of Antimicrobial Polymers, Foldamers, and Small Molecules: From Discovery to Practical Applications
      Tew, Gregory N.; Scott, Richard W.; Klein, Michael L.; De Grado, William F.
      Accounts of Chemical Research (2010), 43 (1), 30-39CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
      A review. Antimicrobial peptides (AMPs) provide protection against a variety of pathogenic bacteria and are, therefore, an important part of the innate immune system. Over the past decade, there has been considerable interest in developing AMPs as i.v. administered antibiotics. However, despite extensive efforts in the pharmaceutical and biotechnol. industry, it has proven difficult to achieve this goal. While researchers have solved some relatively simple problems such as susceptibility to proteolysis, more severe problems have included the expense of the materials, toxicity, poor efficacy, and limited tissue distribution. In this Account, the authors describe their efforts to design and synthesize "foldamers" - short sequence-specific oligomers based on acrylamide and β-amino acid backbones, which fold into well-defined secondary structures - that could act as antimicrobial agents. The authors reasoned that small "foldamers" would be less expensive to produce than peptides, and might have better tissue distribution. It should be easier to fine-tune the structures and activities of these mols. to minimize toxicity. Because the activities of many AMPs depends primarily on their overall physicochem. properties rather than the fine details of their precise amino acid sequences, the authors have designed and synthesized very small "coarse-grained" mols., which are far simpler than naturally produced AMPs. The mol. design of these foldamers epitomizes the pos. charged amphiphilic structures believed to be responsible for the activity of AMPs. The designed oligomers show greater activity than the parent peptides. They have also provided leads for novel small mol. therapeutics that show excellent potency in animal models for multidrug resistant bacterial infections. In addn., such mols. can serve as relatively simple exptl. systems for investigations aimed at understanding the mechanism of action for this class of antimicrobial agents. The foldamers' specificity for bacterial membranes relative to mammalian membranes appears to arise from differences in membrane compn. and phys. properties between these cell types. Furthermore, because exptl. coarse-graining provided such outstanding results, the authors developed computational coarse-grained models to enable mol. dynamic simulations of these mols. with phospholipid membranes. These simulations allow investigation of larger systems for longer times than conventional mol. dynamics simulations, allowing the authors to investigate how physiol. relevant surface concns. of AMP mimics affect the bilayer structure and properties. Finally, the authors apply the principles discovered through this work to the design of inexpensive antimicrobial polymers and materials.
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    14. 14
      Agnihotri, S.; Mukherji, S.; Mukherji, S. Size-controlled silver nanoparticles synthesized over the range 5-100 nm using the same protocol and their antibacterial efficacy. RSC Adv. 2014, 4, 3974– 3983,  DOI: 10.1039/c3ra44507k
      14
      Size-controlled silver nanoparticles synthesized over the range 5-100 nm using the same protocol and their antibacterial efficacy
      Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna
      RSC Advances (2014), 4 (8), 3974-3983CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
      A systematic and detailed study for size-specific antibacterial efficacy of silver nanoparticles (AgNPs) synthesized using a co-redn. approach is presented here. Nucleation and growth kinetics during the synthesis process was precisely controlled and AgNPs of av. size 5, 7, 10, 15, 20, 30, 50, 63, 85, and 100 nm were synthesized with good yield and monodispersity. The authors found the bacteriostatic/bactericidal effect of AgNPs to be size and dose-dependent as detd. by the min. inhibitory concn. (MIC) and min. bactericidal concn. (MBC) of silver nanoparticles against four bacterial strains. Out of the tested strains, Escherichia coli MTCC 443 and Staphylococcus aureus NCIM 5201 are the most and least sensitive strains regardless of AgNP size. For AgNPs with <10 nm size, the antibacterial efficacy was significantly enhanced as revealed through delayed bacterial growth kinetics, corresponding MIC/MBC values and disk diffusion tests. AgNPs of the smallest size, i.e., 5 nm demonstrated the best results and mediated the fastest bactericidal activity against all the tested strains compared to AgNPs having 7 nm and 10 nm sizes at similar bacterial concns. TEM anal. of AgNP treated bacterial cells showed AgNPs on the cell membrane, and AgNPs internalized within the cells.
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    15. 15
      Wang, Y.-W.; Cao, A.; Jiang, Y.; Zhang, X.; Liu, J.-H.; Liu, Y.; Wang, H. Superior antibacterial activity of zinc oxide/graphene oxide composites originating from high zinc concentration localized around bacteria. ACS Appl. Mater. Interfaces 2014, 6, 2791– 2798,  DOI: 10.1021/am4053317
      15
      Superior Antibacterial Activity of Zinc Oxide/Graphene Oxide Composites Originating from High Zinc Concentration Localized around Bacteria
      Wang, Yan-Wen; Cao, Aoneng; Jiang, Yu; Zhang, Xin; Liu, Jia-Hui; Liu, Yuanfang; Wang, Haifang
      ACS Applied Materials & Interfaces (2014), 6 (4), 2791-2798CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      New materials with good antibacterial activity and less toxicity to other species attract numerous research interest. Taking advantage of zinc oxide (ZnO) and graphene oxide (GO), the ZnO/GO composites were prepd. by a facile one-pot reaction to achieve superior antibacterial properties without damaging other species. In the composites, ZnO nanoparticles (NPs), with a size of about 4 nm, homogeneously anchored onto GO sheets. The typical bacterium Escherichia coli and HeLa cell were used to evaluate the antibacterial activity and cytotoxicity of the ZnO/GO composites, resp. The synergistic effects of GO and ZnO NPs led to the superior antibacterial activity of the composites. GO helped the dispersion of ZnO NPs, slowed the dissoln. of ZnO, acted as the storage site for the dissolved zinc ions, and enabled the intimate contact of E. coli with ZnO NPs and zinc ions as well. The close contact enhanced the local zinc concn. pitting on the bacterial membrane and the permeability of the bacterial membrane and thus induced bacterial death. In addn., the ZnO/GO composites were found to be much less toxic to HeLa cells, compared to the equiv. concn. of ZnO NPs in the composites. The results indicate that the ZnO/GO composites are promising disinfection materials to be used in surface coatings on various substrates to effectively inhibit bacterial growth, propagation, and survival in medical devices.
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    16. 16
      Gupta, K.; Singh, R. P.; Pandey, A.; Pandey, A. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli. Beilstein J. Nanotechnol. 2013, 4, 345– 351,  DOI: 10.3762/bjnano.4.40
      16
      Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus., P. aeruginosa and E. coli
      Gupta, Kiran; Singh, R. P.; Pandey, Ashutosh; Pandey, Anjana
      Beilstein Journal of Nanotechnology (2013), 4 (), 345-351, 7 pp.CODEN: BJNEAH; ISSN:2190-4286. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
      This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradn. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol-gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV-vis spectroscopy. The rate of recombination and transfer behavior of the photoexcited electron-hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram pos. (Staphylococcus aureus) and gram neg. (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concns. of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.
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    17. 17
      Ran, X.; Du, Y.; Wang, Z.; Wang, H.; Pu, F.; Ren, J.; Qu, X. Hyaluronic Acid-Templated Ag Nanoparticles/Graphene Oxide Composites for Synergistic Therapy of Bacteria Infection. ACS Appl. Mater. Interfaces 2017, 9, 19717– 19724,  DOI: 10.1021/acsami.7b05584
      17
      Hyaluronic Acid-Templated Ag Nanoparticles/Graphene Oxide Composites for Synergistic Therapy of Bacteria Infection
      Ran, Xiang; Du, Ye; Wang, Zhenzhen; Wang, Huan; Pu, Fang; Ren, Jinsong; Qu, Xiaogang
      ACS Applied Materials & Interfaces (2017), 9 (23), 19717-19724CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Developing methods of decreasing the harm to cell and increasing the antibacterial efficiency is becoming a potential topic of medical treatments. We demonstrated a hyaluronidase-triggered photothermal platform for killing bacteria based on silver nanoparticles (AgNPs) and graphene oxide (GO). The property of the hyaluronidase (HAase)-triggered release provided excellent antibacterial activity against Staphylococcus aureus. Upon illumination of NIR light, the GO-based nanomaterials locally raised the temp., resulting in high mortality of bacteria. The HAase-triggered AgNPs releasing approach for antibacterial allows AgNPs to be protected by hyaluronic acid (HA) template without affecting mammalian cells. The nanocomposites provided antibacterial activity against S. aureus while showing low toxicity to mammal cells. In addn., the GO-HA-AgNPs are prepd. for in vivo expts. and show excellent antibacterial property in wound disinfection model.
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    18. 18
      Kim, T. I.; Kwon, B.; Yoon, J.; Park, I.-J.; Bang, G. S.; Park, Y. K.; Seo, Y.-S.; Choi, S.-Y. Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films. ACS Appl. Mater. Interfaces 2017, 9, 7908– 7917,  DOI: 10.1021/acsami.6b12464
      18
      Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films
      Kim, Tae In; Kwon, Buki; Yoon, Jonghee; Park, Ick-Joon; Bang, Gyeong Sook; Park, YongKeun; Seo, Yeon-Soo; Choi, Sung-Yool
      ACS Applied Materials & Interfaces (2017), 9 (9), 7908-7917CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Two-dimensional (2D) nanomaterials, such as graphene-based materials and transition metal dichalcogenide (TMD) nanosheets, are promising materials for biomedical applications owing to their remarkable cytocompatibility and physicochem. properties. On the basis of their potent antibacterial properties, 2D materials have potential as antibacterial films, wherein the 2D nanosheets are immobilized on the surface and the bacteria may contact with the basal planes of 2D nanosheets dominantly rather than contact with the sharp edges of nanosheets. To address these points, in this study, we prepd. an effective antibacterial surface consisting of representative 2D materials, i.e., graphene oxide (GO) and molybdenum disulfide (MoS2), formed into nanosheets on a transparent substrate for real device applications. The antimicrobial properties of the GO-MoS2 nanocomposite surface toward the Gram-neg. bacteria Escherichia coli were investigated, and the GO-MoS2 nanocomposite exhibited enhanced antimicrobial effects with increased glutathione oxidn. capacity and partial cond. Furthermore, direct imaging of continuous morphol. destruction in the individual bacterial cells having contacts with the GO-MoS2 nanocomposite surface was characterized by holotomog. (HT) microscopy, which could be used to detect the refractive index (RI) distribution of each voxel in bacterial cell and reconstruct the three-dimensional (3D) mapping images of bacteria. In this regard, the decreases in both the vol. (67.2%) and the dry mass (78.8%) of bacterial cells that came in contact with the surface for 80 min were quant. measured, and releasing of intracellular components mediated by membrane and oxidative stress was obsd. Our findings provided new insights into the antibacterial properties of 2D nanocomposite film with label-free tracing of bacterial cell which improve our understanding of antimicrobial activities and opened a window for the 2D nanocomposite as a practical antibacterial film in biomedical applications.
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    19. 19
      Levy, S. B.; Marshall, B. Antibacterial resistance worldwide: causes, challenges and responses. Nat. Med. 2004, 10, S122– S129,  DOI: 10.1038/nm1145
      19
      Antibacterial resistance worldwide: Causes, challenges and responses
      Levy, Stuart B.; Marshall, Bonnie
      Nature Medicine (New York, NY, United States) (2004), 10 (12, Suppl.), S122-S129CODEN: NAMEFI; ISSN:1078-8956. (Nature Publishing Group)
      A review. The optimism of the early period of antimicrobial discovery has been tempered by the emergence of bacterial strains with resistance to these therapeutics. Today, clin. important bacteria are characterized not only by single drug resistance but also by multiple antibiotic resistance: the legacy of past decades of antimicrobial use and misuse. Drug resistance presents an ever-increasing global public health threat that involves all major microbial pathogens and antimicrobial drugs.
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    20. 20
      Mahmoudi, M.; Serpooshan, V. Silver-coated engineered magnetic nanoparticles are promising for the success in the fight against antibacterial resistance threat. ACS Nano 2012, 6, 2656– 2664,  DOI: 10.1021/nn300042m
      20
      Silver-Coated Engineered Magnetic Nanoparticles Are Promising for the Success in the Fight against Antibacterial Resistance Threat
      Mahmoudi, Morteza; Serpooshan, Vahid
      ACS Nano (2012), 6 (3), 2656-2664CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      The combination of patients with poor immune system, prolonged exposure to anti-infective drugs, and cross-infection has given rise to nosocomial infections with highly resistant pathogens, which is going to be a growing threat so termed "antibiotic resistance". Due to their significant antimicrobial activity, silver nanoparticles are recognized as a promising candidate to fight against resistant pathogens; however, there are two major shortcomings with these nanoparticles. First, the silver nanoparticles are highly toxic to the healthy cells; second, due to the protection offered by the biofilm mode of growth, the silver nanoparticles cannot eradicate bacterial biofilms. In order to overcome these limitations, this study introduces a new class of engineered multimodal nanoparticles comprising a magnetic core and a silver ring with a ligand gap. The results indicated promising capability of the designed multimodal nanoparticles for high-yield antibacterial effects and eradication of bacterial biofilms, while the particles were completely compatible with the cells. Utilizing a gold ring as an intermediate coating on the produced nanoparticles may exploit new opportunities for theranosis applications. This will require special consideration in future works.
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    21. 21
      Mei, L.; Lu, Z.; Zhang, W.; Wu, Z.; Zhang, X.; Wang, Y.; Luo, Y.; Li, C.; Jia, Y. Bioconjugated nanoparticles for attachment and penetration into pathogenic bacteria. Biomaterials 2013, 34, 10328– 10337,  DOI: 10.1016/j.biomaterials.2013.09.045
      21
      Bioconjugated nanoparticles for attachment and penetration into pathogenic bacteria
      Mei, Lin; Lu, Zhentan; Zhang, Wei; Wu, Zhongming; Zhang, Xinge; Wang, Yanan; Luo, Yuting; Li, Chaoxing; Jia, Yanxia
      Biomaterials (2013), 34 (38), 10328-10337CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
      As an antimicrobial agent, silver nanoparticles functionalized with both bacitracin A and polymyxin E (AgNPs-BA&PE) were designed and synthesized with complementary antibacterial functions to act against gram-pos. and gram-neg. bacteria. AgNPs-BA&PE could easily get attached and penetrate into the bacterial cell membrane through surface-immobilized BA and PE with a membrane target, resulting in up to 10-fold increase in the antibacterial activity, without the emergence of bacterial resistance. Anal. of the antimicrobial mechanism confirmed that the synthesized nanoparticles caused disorganization of the bacterial cytomembrane and leakage of cytoplasmic contents. This antimicrobial agent with better biocompatibility can promote healing of infected wounds, and has promising and useful applications in biomedical devices and antibacterial control systems.
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    22. 22
      Chellat, M. F.; Raguž, L.; Riedl, R. Targeting Antibiotic Resistance. Angew. Chem., Int. Ed. 2016, 55, 6600– 6626,  DOI: 10.1002/anie.201506818
      22
      Targeting Antibiotic Resistance
      Chellat, Mathieu F.; Raguz, Luka; Riedl, Rainer
      Angewandte Chemie, International Edition (2016), 55 (23), 6600-6626CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A review. Finding strategies against the development of antibiotic resistance is a major global challenge for the life sciences community and for public health. The past decades have seen a dramatic worldwide increase in human-pathogenic bacteria that are resistant to one or multiple antibiotics. More and more infections caused by resistant microorganisms fail to respond to conventional treatment, and in some cases, even last-resort antibiotics have lost their power. In addn., industry pipelines for the development of novel antibiotics have run dry over the past decades. A recent world health day by the World Health Organization titled "Combat drug resistance: no action today means no cure tomorrow" triggered an increase in research activity, and several promising strategies have been developed to restore treatment options against infections by resistant bacterial pathogens.
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    23. 23
      Zhao, C.; Deng, B.; Chen, G.; Lei, B.; Hua, H.; Peng, H.; Yan, Z. Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating. Nano Res. 2016, 9, 963– 973,  DOI: 10.1007/s122710.1007/s12274-016-0984-2
      23
      Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating
      Zhao, Chen; Deng, Bing; Chen, Guanchu; Lei, Bo; Hua, Hong; Peng, Hailin; Yan, Zhimin
      Nano Research (2016), 9 (4), 963-973CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)
      New types of antimicrobial systems are urgently needed owing to the emergence of pathogenic microbial strains that gain resistance to antibiotics commonly used in daily life and medical care. In this study, we developed for the first time a broad-spectrum and robust antimicrobial thin film coating based on large-area chem. vapor deposition (CVD)-grown graphene-wrapped silver nanowires (AgNWs). The antimicrobial graphene/AgNW hybrid coating can be applied on com. flexible transparent ethylene vinyl acetate/ polyethylene terephthalate (EVA/PET) plastic films by a full roll-to-roll process. The graphene/AgNW hybrid coating showed broad-spectrum antimicrobial activity against Gram-neg. (Escherichia coli) and Gram-pos. bacteria (Staphylococcus aureus), and fungi (Candida albicans). This effect was attributed to a weaker microbial attachment to the ultra-smooth graphene film and the sterilization capacity of Ag+, which is sustainably released from the AgNWs and presumably enhanced by the electrochem. corrosion of AgNWs. Moreover, the robust antimicrobial activity of the graphene/AgNW coating was reinforced by AgNW encapsulation by graphene. Furthermore, the antimicrobial efficiency could be enhanced to ∼100% by water electrolysis by using the conductive graphene/AgNW coating as a cathode. We developed a transparent and flexible antimicrobial cover made of graphene/AgNW/EVA/PET and an antimicrobial denture coated by graphene/ AgNW, to show the potential applications of the antimicrobial materials.
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    24. 24
      Huh, A. J.; Kwon, Y. J. ″Nanoantibiotics″: A new paradigm for treating infectious diseases using nanomaterials in the antibiotics resistant era. J. Controlled Release 2011, 156, 128– 145,  DOI: 10.1016/j.jconrel.2011.07.002
      24
      "Nanoantibiotics": A new paradigm for treating infectious diseases using nanomaterials in the antibiotics resistant era
      Huh, Ae Jung; Kwon, Young Jik
      Journal of Controlled Release (2011), 156 (2), 128-145CODEN: JCREEC; ISSN:0168-3659. (Elsevier B.V.)
      A review. Despite the fact that we live in an era of advanced and innovative technologies for elucidating underlying mechanisms of diseases and molecularly designing new drugs, infectious diseases continue to be one of the greatest health challenges worldwide. The main drawbacks for conventional antimicrobial agents are the development of multiple drug resistance and adverse side effects. Drug resistance enforces high dose administration of antibiotics, often generating intolerable toxicity, development of new antibiotics, and requests for significant economic, labor, and time investments. Recently, nontraditional antibiotic agents have been of tremendous interest in overcoming resistance that is developed by several pathogenic microorganisms against most of the commonly used antibiotics. Esp., several classes of antimicrobial nanoparticles (NPs) and nanosized carriers for antibiotics delivery have proven their effectiveness for treating infectious diseases, including antibiotics resistant ones, in vitro as well as in animal models. This review summarizes emerging efforts in combating against infectious diseases, particularly using antimicrobial NPs and antibiotics delivery systems as new tools to tackle the current challenges in treating infectious diseases.
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    25. 25
      McBain, A. J.; Ledder, R. G.; Moore, L. E.; Catrenich, C. E.; Gilbert, P. Effects of quaternary-ammonium-based formulations on bacterial community dynamics and antimicrobial susceptibility. Appl. Environ. Microbiol. 2004, 70, 3449– 3456,  DOI: 10.1128/AEM.70.6.3449-3456.2004
      25
      Effects of quaternary-ammonium-based formulations on bacterial community dynamics and antimicrobial susceptibility
      McBain, Andrew J.; Ledder, Ruth G.; Moore, Louise E.; Catrenich, Carl E.; Gilbert, Peter
      Applied and Environmental Microbiology (2004), 70 (6), 3449-3456CODEN: AEMIDF; ISSN:0099-2240. (American Society for Microbiology)
      Quaternary ammonium compds. (QACs) are widely used as adjuncts to hygiene in domestic cleaning products. Current concern that the increased use of such biocides in consumer products might contribute to the emergence of antibiotic resistance has led us to examine the effects of a QAC-contg. domestic cleaning fluid on the population dynamics and antimicrobial susceptibility of domestic sink drain biofilm communities. QAC susceptibilities of numerically dominant, culturable drain bacteria (15 genera, 17 species) were detd. in vitro before and after repeated QAC exposure (14 passages). A fully characterized drain microcosm was then exposed to short-term (12 days) and long-term (3 mo) dosing with a QAC-contg. domestic detergent (QD). QAC exposure of isolated cultures caused both increases (three species) and circa twofold decreases (six species) in QAC susceptibility. The susceptibility of Ralstonia sp. was considerably decreased following 14 consecutive QAC passages. Control drain microcosm biofilms maintained dynamic stability, as evidenced by culture and denaturing gradient gel electrophoresis (DGGE) anal. Bacterial population densities were largely unaffected during short-term exposure to use levels of QD, although 50% QD caused circa 10-fold viability redns. DGGE anal. supported these observations; identified the major microcosm genera as Pseudomonas, Pseudoalteromonas, Erwinia, and Enterobacter, and showed that aeromonads increased in abundance under 10 to 50% QD. Long-term exposure of the microcosms to QD did not significantly alter the pattern of antimicrobial susceptibility. These data demonstrate the recalcitrance of domestic drain biofilms toward QAC and that although repeated QAC exposure of drain isolates in pure culture results in susceptibility change in some test bacteria, such changes do not necessarily occur within complex communities.
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    26. 26
      Kawabata, N.; Nishiguchi, M. Antibacterial activity of soluble pyridinium-type polymers. Appl. Environ. Microbiol. 1988, 54, 2532– 2535
      26
      Antibacterial activity of soluble pyridinium-type polymers
      Kawabata, Nariyoshi; Nishiguchi, Masayuki
      Applied and Environmental Microbiology (1988), 54 (10), 2532-5CODEN: AEMIDF; ISSN:0099-2240.
      Cross-linked poly(N-benzyl-4-vinylpyridinium halide) (designated insol. BVP) was previously reported to capture bacterial cells alive by contact. The corresponding linear polymer, poly(N-benzyl-4-vinylpyridinium salt) (designated sol. BVP), exhibited antibacterial activity. This sol. pyridinium-type polymer showed strong antibacterial activity against gram-pos. bacteria, whereas it was less active against gram-neg. bacteria. The antibacterial activity of this cationic, polymeric disinfectant was considerably greater than that of the corresponding monomeric compd. and was approx. equal to that of conventional disinfectants such as benzalkonium chloride and chlorohexidine.
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      PMID: 3202632.

    27. 27
      Beyth, N.; Yudovin-Farber, I.; Bahir, R.; Domb, A. J.; Weiss, E. I. Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans. Biomaterials 2006, 27, 3995– 4002,  DOI: 10.1016/j.biomaterials.2006.03.003
      27
      Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans
      Beyth, Nurit; Yudovin-Farber, Ira; Bahir, Ran; Domb, Abraham J.; Weiss, Ervin I.
      Biomaterials (2006), 27 (21), 3995-4002CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
      The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1% wt./wt. with clin. used bonding, flowable and hybrid dental composite resins and cured by light polymn. was studied. The antibacterial activity was tested with Streptococcus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity (p<0.001) was found in all 3 types of composite resins incorporated with the synthesized nanoparticles. The effect lasted for at least 1 mo. SEM demonstrated bacterial debris and no streptococcal chains at 24 h of bacterial contact. The addn. of 1% wt./wt. of nanoparticles did not affect the flexural modulus and the flexural strength of the dental composite materials. The results indicate that quaternary ammonium PEI nanoparticles immobilized in resin-based materials have a strong antibacterial activity upon contact without leach-out of the nanoparticles and without compromise in mech. properties.
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    28. 28
      Gilbert, P.; McBain, A. J. Potential impact of increased use of biocides in consumer products on prevalence of antibiotic resistance. Clin. Microbiol. Rev. 2003, 16, 189– 208,  DOI: 10.1128/CMR.16.2.189-208.2003
      28
      Potential impact of increased use of biocides in consumer products on prevalence of antibiotic resistance
      Gilbert, Peter; McBain, Andrew J.
      Clinical Microbiology Reviews (2003), 16 (2), 189-208CODEN: CMIREX; ISSN:0893-8512. (American Society for Microbiology)
      A review. There has recently been much controversy surrounding the increased use of antibacterial substances in a wide range of consumer products and the possibility that, as with antibiotics, indiscriminate use of biocides might contribute to the overall pattern of susceptibility in the general environment and in the clinic. Such speculation, based on the isolation of resistant mutants from in vitro monoculture expts., is not reflected by an emergence of biocide-resistant strains in vivo. This review provides a broad coverage of the biocide and resistance literature and evaluates the potential risks, perceived from such lab. monoculture expts., against evidence gathered over 50 yr of field studies. An explanation for the continued effectiveness of broad-spectrum biocidal agents against the decline in efficacy of therapeutic agents is provided based on the fitness costs of resistance and the ubiquity of naturally occurring substances that possess antibacterial effect. While the authors conclude from this review of the literature that the incorporation of antibacterial agents into a widening sphere of personal products has had little or no impact on the patterns of microbial susceptibility obsd. in the environment, the assocd. risks remain finite. The use of such products should therefore be assocd. with a clear demonstration of added value either to consumer health or to the product life. Hygienic products should therefore be targeted to applications for which the risks have been established.
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    29. 29
      Jiao, Y.; Niu, L.-n.; Ma, S.; Li, J.; Tay, F. R.; Chen, J.-h. Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance. Prog. Polym. Sci. 2017, 71, 53– 90,  DOI: 10.1016/j.progpolymsci.2017.03.001
      29
      Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance
      Jiao, Yang; Niu, Li-na; Ma, Sai; Li, Jing; Tay, Franklin R.; Chen, Ji-hua
      Progress in Polymer Science (2017), 71 (), 53-90CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
      Microbial infections affect humans worldwide. Many quaternary ammonium compds. have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for prepn. of antimicrobial biomaterials. Various polymn. techniques have been employed to prep. antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymn. techniques enable precise control over macromol. structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technol. developments have also been accompanied by potential toxicol. and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-contg. biomaterials that are based on randomized human clin. trials, the golden std. in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.
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    30. 30
      Mei, L.; Lu, Z.; Zhang, X.; Li, C.; Jia, Y. Polymer-Ag Nanocomposites with Enhanced Antimicrobial Activity against Bacterial Infection. ACS Appl. Mater. Interfaces 2014, 6, 15813– 15821,  DOI: 10.1021/am502886m
      30
      Polymer-Ag Nanocomposites with Enhanced Antimicrobial Activity against Bacterial Infection
      Mei, Lin; Lu, Zhentan; Zhang, Xinge; Li, Chaoxing; Jia, Yanxia
      ACS Applied Materials & Interfaces (2014), 6 (18), 15813-15821CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Herein, a nontoxic nanocomposite is synthesized by redn. of silver nitrate in the presence of a cationic polymer displaying strong antimicrobial activity against bacterial infection. These nanocomposites with a large concn. of pos. charge promote their adsorption to bacterial membranes through electrostatic interaction. Moreover, the synthesized nanocomposites with polyvalent and synergistic antimicrobial effects can effectively kill both Gram-pos. and Gram-neg. bacteria without the emergence of bacterial resistance. Morphol. changes obtained by transmission electron microscope observation show that these nanocomposites can cause leakage and chaos of intracellular contents. Anal. of the antimicrobial mechanism confirms that the lethal action of nanocomposites against the bacteria started with disruption of the bacterial membrane, subsequent cellular internalization of the nanoparticles, and inhibition of intracellular enzymic activity. This novel antimicrobial material with good cytocompatibility promotes healing of infected wounds in diabetic rats, and has a promising future in the treatment of other infectious diseases.
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    31. 31
      Muñoz-Bonilla, A.; Fernández-García, M. Polymeric materials with antimicrobial activity. Prog. Polym. Sci. 2012, 37, 281– 339,  DOI: 10.1039/978178262499810.1016/j.progpolymsci.2011.08.005
      31
      Polymeric materials with antimicrobial activity
      Munoz-Bonilla, Alexandra; Fernandez-Garcia, Marta
      Progress in Polymer Science (2012), 37 (2), 281-339CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
      A review. This article describes the state of the art in the field of antimicrobial polymeric systems during the last decade. Keeping in mind the multitude of existing systems, a classification of the different materials is carried out dividing basically those synthetic polymers that: (a) exhibit antimicrobial activity by themselves; (b) those whose biocidal activity is conferred through their chem. modification; (c) those that incorporate antimicrobial org. compds. with either low or high mol. wt.; and (d) those that involve the addn. of active inorg. systems. This classification is not absolutely unique and in occasions some described polymeric systems could belong to more than one section. However, the purpose of this review is to provide a handy overall vision of the antimicrobial synthetic polymers world.
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    32. 32
      Altay, E.; Yapaöz, M. A.; Keskin, B.; Yucesan, G.; Eren, T. Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP. Colloids Surf., B 2015, 127, 73– 78,  DOI: 10.1016/j.colsurfb.2015.01.020
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      Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP
      Altay, Esra; Yapaoz, Melda Altikatoglu; Keskin, Bahadir; Yucesan, Gundog; Eren, Tarik
      Colloids and Surfaces, B: Biointerfaces (2015), 127 (), 73-78CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
      The purpose of this study is to understand the antibacterial properties of cationic polymers on solid surfaces by investigating the structure-activity relationships. The polymer synthesis was carried via ring opening metathesis polymn. (ROMP) of oxanorbornene derivs. Modulation of mol. wts. and alkyl chain lengths of the polymers were studied to investigate the antibacterial properties on the glass surface. Fluorescein (Na salt) staining contact angle measurements were used to characterize the pos. charge d. and hydrophobicity on the polymer coated surfaces. Pos. charge d. for the surface coated polymers with mol. wts. of 3000 and 10,000 g mol-1 is obsd. to be in the range of 2.3-28.5 nmol cm-2. The ROMP based cationic pyridinium polymer with hexyl unit exhibited the highest bactericidal efficiency against Escherichia coli on solid surface killing 99% of the bacteria in 5 min. However, Ph and octyl functionalized quaternary pyridinium groups exhibited lower biocidal properties on the solid surfaces compared to their soln. phase biocidal properties. Studying the effect of threshold polymer concns. on the antibacterial properties indicated that changing the concns. of polymer coatings on the solid surface dramatically influences antibacterial efficiency.
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    33. 33
      Chen, J.; Peng, H.; Wang, X.; Shao, F.; Yuan, Z.; Han, H. Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation. Nanoscale 2014, 6, 1879– 1889,  DOI: 10.1039/C3NR04941H
      33
      Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation
      Chen, Juanni; Peng, Hui; Wang, Xiuping; Shao, Feng; Yuan, Zhaodong; Han, Heyou
      Nanoscale (2014), 6 (3), 1879-1889CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
      To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular study was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). GO had a powerful effect on the reprodn. of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range of aggregated graphene oxide sheets, resulting in the local perturbation of their cell membrane and inducing the decrease of the bacterial membrane potential and the leakage of electrolytes of fungal spores. It is likely that GO interacts with the pathogens by mech. wrapping and locally damaging the cell membrane and finally causing cell lysis, which may be one of the major toxicity actions of GO against phytopathogens. The antibacterial mode proposed in this study suggests that the GO may possess antibacterial activity against more multi-resistant bacterial and fungal phytopathogens, and provides useful information about the application of GO in resisting crop diseases.
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    34. 34
      Rasool, K.; Helal, M.; Ali, A.; Ren, C. E.; Gogotsi, Y.; Mahmoud, K. A. Antibacterial Activity of Ti3C2Tx MXene. ACS Nano 2016, 10, 3674– 3684,  DOI: 10.1021/acsnano.6b00181
      34
      Antibacterial activity of Ti3C2Tx MXene
      Rasool, Kashif; Helal, Mohamed; Ali, Adnan; Ren, Chang E.; Gogotsi, Yury; Mahmoud, Khaled A.
      ACS Nano (2016), 10 (3), 3674-3684CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      MXenes are a family of atomically thin, two-dimensional (2D) transition metal carbides and carbonitrides with many attractive properties. Two-dimensional Ti3C2Tx (MXene) has been recently explored for applications in water desalination/purifn. membranes. A major success indicator for any water treatment membrane is the resistance to biofouling. To validate this and to understand better the health and environmental impacts of the new 2D carbides, the authors investigated the antibacterial properties of single- and few-layer Ti3C2Tx MXene flakes in colloidal soln. The antibacterial properties of Ti3C2Tx were tested against Escherichia coli and Bacillus subtilis by using bacterial growth curves based on optical densities (OD) and colonies growth on agar nutritive plates. Ti3C2Tx shows a greater antibacterial efficiency toward both Gram-neg. E. coli and Gram-pos. B. subtilis compared with graphene oxide (GO), which has been widely reported as an antibacterial agent. Concn.-dependent antibacterial activity was obsd. and more than 98% bacterial cell viability loss was found at 200 μg/mL Ti3C2Tx for both bacterial cells within 4 h of exposure, as confirmed by colony forming unit (CFU) and regrowth curve. An antibacterial mechanism investigation by scanning and transmission electron microscopy coupled with a lactate dehydrogenase release assay indicated damage to the cell membrane, which resulted in release of cytoplasmic materials from the bacterial cells. Reactive oxygen species (ROS) dependent and independent stress induction by Ti3C2Tx was investigated in two sep. abiotic assays. MXenes are expected to be resistant to biofouling and to offer bactericidal properties.
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    35. 35
      Bing, W.; Chen, Z.; Sun, H.; Shi, P.; Gao, N.; Ren, J.; Qu, X. Visible-light-driven enhanced antibacterial and biofilm elimination activity of graphitic carbon nitride by embedded Ag nanoparticles. Nano Res. 2015, 8, 1648– 1658,  DOI: 10.1007/s122710.1007/s12274-014-0654-1
      35
      Visible-light-driven enhanced antibacterial and biofilm elimination activity of graphitic carbon nitride by embedded Ag nanoparticles
      Bing, Wei; Chen, Zhaowei; Sun, Hanjun; Shi, Peng; Gao, Nao; Ren, Jinsong; Qu, Xiaogang
      Nano Research (2015), 8 (5), 1648-1658CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)
      Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles (NPs) on a semiconductor, since the noble metal NPs act as excellent electron acceptors which inhibit the quick recombination of the photoexcited electron-hole pairs and thereby enhance the generation of reactive oxygen species (ROS). Herein, a highly effective platform, graphitic carbon nitride (g-C3N4) nanosheets with embedded Ag nanoparticles (Ag/g-C3N4), was synthesized by a facile route. Under visible light irradn., the ROS prodn. of Ag/g-C3N4 nanohybrids was greatly improved compared with pristine g-C3N4 nanosheets, and moreover, the nanohybrids showed enhanced antibacterial efficacy and ability to disperse bacterial biofilms. We demonstrate for the first time that the Ag/g-C3N4 nanohybrids are efficient bactericidal agents under visible light irradn., and can also provide a new way for biofilm elimination. The enhanced antibacterial properties and biofilm-disrupting ability of Ag/g-C3N4 nanohybrids may offer many biomedical applications. [Figure not available: see fulltext.].
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    36. 36
      Hou, J.; Miao, L.; Wang, C.; Wang, P.; Ao, Y.; Qian, J.; Dai, S. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes. J. Hazard. Mater. 2014, 276, 164– 170,  DOI: 10.1016/j.jhazmat.2014.04.048
      36
      Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes
      Hou, Jun; Miao, Lingzhan; Wang, Chao; Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan
      Journal of Hazardous Materials (2014), 276 (), 164-170CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)
      The presence of ZnO NPs in waste streams can neg. affect the efficiency of biol. nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. The temporal and spatial inhibitory effects of ZnO NPs on the O2 respiration activities of aerobic wastewater biofilms were investigated using an O2 microelectrode. The resulting time-course microelectrode measurements demonstrated that ZnO NPs inhibited O2 respiration within 2 h. The spatial distributions of net specific O2 respiration were detd. in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. SEM anal. showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. The inhibition of O2 respiration induced by higher concns. of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissoln. of the ZnO NPs.
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    37. 37
      Fu, F.; Li, L.; Liu, L.; Cai, J.; Zhang, Y.; Zhou, J.; Zhang, L. Construction of Cellulose Based ZnO Nanocomposite Films with Antibacterial Properties through One-Step Coagulation. ACS Appl. Mater. Interfaces 2015, 7, 2597– 2606,  DOI: 10.1021/am507639b
      37
      Construction of Cellulose Based ZnO Nanocomposite Films with Antibacterial Properties through One-Step Coagulation
      Fu, Feiya; Li, Lingyan; Liu, Lianjie; Cai, Jun; Zhang, Yaping; Zhou, Jinping; Zhang, Lina
      ACS Applied Materials & Interfaces (2015), 7 (4), 2597-2606CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Cellulose based ZnO nanocomposite (RCZ) films were prepd. from cellulose carbamate-NaOH/ZnO solns. through one-step coagulation in Na2SO4 aq. solns. The structure and properties of RCZ films were characterized using XRD, FTIR, XPS, SEM, TEM, TG, tensile testing, and antibacterial activity tests. The content of ZnO in RCZ films was obtained in the range of 2.7-15.1 wt %. ZnO nanoparticles with a hexagonal wurtzite structure agglomerated into large particles, which firmly embedded in the cellulose matrix. RCZ films displayed good mech. properties and high thermal stability. Moreover, the films exhibited excellent UV-blocking properties and antibacterial activities against Staphylococcus aureus and Escherichia coli. A dramatic redn. in viable bacteria was obsd. within 3 h of exposure, while all of the bacteria were killed within 6 h. This work provided a novel and simple pathway for the prepn. of regenerated cellulose films with ZnO nanoparticles for application as functional biomaterials.
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    38. 38
      Hsu, M.-H.; Chang, C.-J. Ag-doped ZnO nanorods coated metal wire meshes as hierarchical photocatalysts with high visible-light driven photoactivity and photostability. J. Hazard. Mater. 2014, 278, 444– 453,  DOI: 10.1016/j.jhazmat.2014.06.038
      38
      Ag-doped ZnO nanorods coated metal wire meshes as hierarchical photocatalysts with high visible-light driven photoactivity and photostability
      Hsu, Mu-Hsiang; Chang, Chi-Jung
      Journal of Hazardous Materials (2014), 278 (), 444-453CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)
      Ag-doped ZnO nanorods were grown on stainless-steel wire meshes to fabricate the hierarchical photocatalysts with excellent visible light driven activity and anti-photocorrosion property. Effects of Ag doping and the surface structure on the surface chem., surface wetting properties, absorption band shift, photoelectrochem. response, and photocatalytic decolorization properties of the hierarchical photocatalysts, together with the stability of photocatalytic activity for recycled photocatalysts were investigated. Ag doping leads to red-shift in the absorption band and increased visible light absorption. Nanorods coated wire meshes hierarchical structure not only increases the surface area of photocatalysts but also makes the surface hydrophilic. The photocatalytic activity enhancement and reduced photocorrosion can be achieved because of increased surface area, enhanced hydrophilicity, and the interaction between the metal wire/ZnO and Ag/ZnO heterostructure interface which can improve the charge sepn. of photogenerated charge carriers.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1WjsbzJ&md5=0ad72f0a8cd50e4b6ef4332c37e1bcbb
    39. 39
      Jian, H.-J.; Wu, R.-S.; Lin, T.-Y.; Li, Y.-J.; Lin, H.-J.; Harroun, S. G.; Lai, J.-Y.; Huang, C.-C. Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis. ACS Nano 2017, 11, 6703– 6716,  DOI: 10.1021/acsnano.7b01023
      39
      Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis
      Jian, Hong-Jyuan; Wu, Ren-Siang; Lin, Tzu-Yu; Li, Yu-Jia; Lin, Han-Jia; Harroun, Scott G.; Lai, Jui-Yang; Huang, Chih-Ching
      ACS Nano (2017), 11 (7), 6703-6716CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      We have developed a one-step method to synthesize carbon quantum dots (CQDPAs) from biogenic polyamines (PAs) as an antibacterial agent for topical treatment of bacterial keratitis (BK). CQDs synthesized by direct pyrolysis of spermidine (Spd) powder through a simple dry heating treatment exhibit a soly. and yield much higher than those from putrescine and spermine. We demonstrate that CQDs obtained from Spds (CQDSpds) possess effective antibacterial activities against non-multidrug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica serovar Enteritidis bacteria and also against the multidrug-resistant bacteria, methicillin-resistant S. aureus. The minimal inhibitory concn. (MIC) of CQDSpds is ∼2500-fold lower than that of spermidine alone, demonstrating their strong antibacterial capabilities. Investigation of the possible mechanisms behind the antibacterial activities of the as-synthesized CQDSpds indicates that the super-cationic CQDSpds with small size (diam. ca. 6 nm) and highly pos. charge (ζ-potential ca. +45 mV) cause severe disruption of the bacterial membrane. In vitro cytotoxicity, hemolysis, hemagglutination, genotoxicity, and oxidative stress and in vivo morphol. and physiol. cornea change evaluations show the good biocompatibility of CQDSpds. Furthermore, topical ocular administration of CQDSpds can induce the opening of the tight junction of corneal epithelial cells, thereby leading to great antibacterial treatment of S. aureus-induced BK in rabbits. Our results suggest that CQDSpds are a promising antibacterial candidate for clin. applications in treating eye-related bacterial infections and even persistent bacteria-induced infections.
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    40. 40
      Yuan, H.; Liu, Z.; Liu, L.; Lv, F.; Wang, Y.; Wang, S. Cationic conjugated polymers for discrimination of microbial pathogens. Adv. Mater. 2014, 26, 4333– 4338,  DOI: 10.1002/adma.201400636
      40
      Cationic Conjugated Polymers for Discrimination of Microbial Pathogens
      Yuan, Huanxiang; Liu, Zhang; Liu, Libing; Lv, Fengting; Wang, Yilin; Wang, Shu
      Advanced Materials (Weinheim, Germany) (2014), 26 (25), 4333-4338CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A cationic poly(p-phenylene vinylene) (PPV-NMe3+) has been synthesized for rapid and simple discrimination of fungi, Gram-pos., and Gram-neg. bacteria. The thermodynamical and the zeta potential measurements exhibit that the binding of PPV-NMe3+ to Candida albicans and Escherichia coli is dominated by electrostatic interactions, while hydrophobic interactions for PPV-NMe3+ and Bacillus subtilis. Single self-luminous PPV-NMe3+ mols. could discriminate fungi, Gram-pos. bacteria, and Gram-neg. bacteria under a fluorescence microscope only via varying the ion strengths of the buffer soln. in a rapid and simple way. There are several unique features for the authors' new assay system. First, the method is rapid. It takes only <3 h to complete the anal. including culturing, detecting, and discriminating the pathogens. Second, the method is much simpler than other assays (such as PCR). Direct discrimination by the fluorescence intensity under a fluorescence microscope is the most important characteristic of the assay. Third, this method can be applied to complicated situations in which the targets consist of two or three classes of microorganisms (fungi, Gram-pos. bacteria, and Gram-neg. bacteria). Thus cationic conjugated polymers exhibit high potential as diagnostic materials for the detection and discrimination of pathogens.
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    41. 41
      Zhu, C.; Yang, Q.; Lv, F.; Liu, L.; Wang, S. Conjugated Polymer-Coated Bacteria for Multimodal Intracellular and Extracellular Anticancer Activity. Adv. Mater. 2013, 25, 1203– 1208,  DOI: 10.1002/adma.201204550
      41
      Conjugated Polymer-Coated Bacteria for Multimodal Intracellular and Extracellular Anticancer Activity
      Zhu, Chunlei; Yang, Qiong; Lv, Fengting; Liu, Libing; Wang, Shu
      Advanced Materials (Weinheim, Germany) (2013), 25 (8), 1203-1208CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
      We developed a bacterial vector-based drug loading, delivery and release system for multimodal anticancer activity. The loaded drug is polypeptide exotoxin A of Pseudomonas aeruginosa (PE66). We first constructed a toxin-expressing plasmid pET28a-PE66 and subsequently installed it into the expression vector BL21 to fabricate the bacterial micro-/nanovectors. A conjugated polyelectrolyte (CP) could be used for coating E. coli by electrostatic and hydrophobic interactions. Facilitated by the collaborative release effect caused by CP and membrane- disrupting antibiotic polymyxin B, the loaded toxin PE66 can considerably leak out from the capsules and exert their toxic functions on cancer cells to initiate programmed cell apoptosis.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVyhsrzK&md5=3f12f6c6a273823c45b622b6da07e8ba
    42. 42
      Wang, G.; Jin, W.; Qasim, A. M.; Gao, A.; Peng, X.; Li, W.; Feng, H.; Chu, P. K. Antibacterial effects of titanium embedded with silver nanoparticles based on electron-transfer-induced reactive oxygen species. Biomaterials 2017, 124, 25– 34,  DOI: 10.1016/j.biomaterials.2017.01.028
      42
      Antibacterial effects of titanium embedded with silver nanoparticles based on electron-transfer-induced reactive oxygen species
      Wang, Guomin; Jin, Weihong; Qasim, Abdul Mateen; Gao, Ang; Peng, Xiang; Li, Wan; Feng, Hongqing; Chu, Paul K.
      Biomaterials (2017), 124 (), 25-34CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
      Although titanium embedded with silver nanoparticles (Ag-NPs@Ti) are suitable for biomedical implants because of the good cytocompatibility and antibacterial characteristics, the exact antibacterial mechanism is not well understood. In the present work, the antibacterial mechanisms of Ag-NPs@Ti prepd. by plasma immersion ion implantation (PIII) are explored in details. The antibacterial effects of the Ag-NPs depend on the cond. of the substrate revealing the importance of electron transfer in the antibacterial process. In addn., electron transfer between the Ag-NPs and titanium substrate produces bursts of reactive oxygen species (ROS) in both the bacteria cells and culture medium. ROS leads to bacteria death by inducing intracellular oxidn., membrane potential variation, and cellular contents release and the antibacterial ability of Ag-NPs@Ti is inhibited appreciably after adding ROS scavengers. Even though ROS signals are detected from osteoblasts cultured on Ag-NPs@Ti, the cell compatibility is not impaired. This electron-transfer-based antibacterial process which produces ROS provides insights into the design of biomaterials with both antibacterial properties and cytocompatibility.
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    43. 43
      Courtney, C. M.; Goodman, S. M.; McDaniel, J. A.; Madinger, N. E.; Chatterjee, A.; Nagpal, P. Photoexcited quantum dots for killing multidrug-resistant bacteria. Nat. Mater. 2016, 15, 529– 534,  DOI: 10.1038/nmat4542
      43
      Photoexcited quantum dots for killing multidrug-resistant bacteria
      Courtney, Colleen M.; Goodman, Samuel M.; McDaniel, Jessica A.; Madinger, Nancy E.; Chatterjee, Anushree; Nagpal, Prashant
      Nature Materials (2016), 15 (5), 529-534CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      Multidrug-resistant bacterial infections are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Metal nanoparticles can induce cell death, yet the toxicity effect is typically nonspecific. Here, we show that photoexcited quantum dots (QDs) can kill a wide range of multidrug-resistant bacterial clin. isolates, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Salmonella typhimurium. The killing effect is independent of material and controlled by the redox potentials of the photogenerated charge carriers, which selectively alter the cellular redox state. We also show that the QDs can be tailored to kill 92% of bacterial cells in a monoculture, and in a co-culture of E. coli and HEK 293T cells, while leaving the mammalian cells intact, or to increase bacterial proliferation. Photoexcited QDs could be used in the study of the effect of redox states on living systems, and lead to clin. phototherapy for the treatment of infections.
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    44. 44
      Cabiscol, E.; Tamarit, J.; Ros, J. Oxidative stress in bacteria and protein damage by reactive oxygen species. Int. Microbiol. 2000, 3, 3– 8
      44
      Oxidative stress in bacteria and protein damage by reactive oxygen species
      Cabiscol, Elisa; Tamarit, Jordi; Ros, Joaquim
      International Microbiology (2000), 3 (1), 3-8CODEN: INMIFW; ISSN:1139-6709. (Springer-Verlag Iberica)
      A review with 50 refs. The advent of O2 in the atm. was among the first major pollution events that occurred on earth. The reaction between ferrous iron, very abundant in the reductive early atm., and oxygen results in the formation of harmful superoxide and hydroxyl radicals, which affect all macromols. (DNA, lipids and proteins). Living organisms have to build up mechanisms to protect themselves against oxidative stress, with enzymes such as catalase and superoxide dismutase, small proteins like thioredoxin and glutaredoxin, and mols. such as glutathione. Bacterial genetic responses to oxidative stress are controlled by two major transcriptional regulators (OxyR and SoxRS). This paper reviews major key points in the generation of reactive oxygen species in bacteria, defense mechanisms and genetic responses to oxidative stress. Special attention is paid to the oxidative damage to proteins.
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      PMID: 10963327.

    45. 45
      Blokhina, O.; Virolainen, E.; Fagerstedt, K. V. Antioxidants, oxidative damage and oxygen deprivation stress: a review. Ann. Bot. 2003, 91, 179– 194,  DOI: 10.1093/aob/mcf118
      45
      Antioxidants, oxidative damage and oxygen deprivation stress: A review
      Blokhina, Olga; Virolainen, Eija; Fagerstedt, Kurt V.
      Annals of Botany (Oxford, United Kingdom) (2003), 91 (Spec. Issue), 179-194CODEN: ANBOA4; ISSN:0305-7364. (Oxford University Press)
      A review. Oxidative stress is induced by a wide range of environmental factors including UV stress, pathogen invasion (hypersensitive reaction), herbicide action and oxygen shortage. Oxygen deprivation stress in plant cells is distinguished by three physiol. different states: transient hypoxia anoxia and reoxygenation. Generation of reactive oxygen species (ROS) is characteristic for hypoxia and esp. for reoxygenation. Of the ROS, hydrogen peroxide (H2O2) and superoxide (O2.-) are both produced in a no. of cellular reactions, including the iron-catalyzed Fenton reaction, and by various enzymes such as lipoxygenases, peroxidases, NADPH oxidase and xanthine oxidase. The main cellular components susceptible to damage by free radicals are lipids (peroxidn. of unsatd. fatty acids in membranes), proteins (denaturation), carbohydrates and nucleic acids. Consequences of hypoxia-induced oxidative stress depend on tissue and/or species (i.e. their tolerance to anoxia), on membrane properties, on endogenous antioxidant content and on the ability to induce the response in the antioxidant system. Effective utilization of energy resources (starch, sugars) and the switch to anaerobic metab. and the preservation of the redox status of the cell are vital for survival. The formation of ROS is prevented by an antioxidant system: low mol. mass antioxidants (ascorbic acid, glutathione, tocopherols), enzymes regenerating the reduced forms of antioxidants, and ROS-interacting enzymes such as SOD, peroxidases and catalases. In plant tissues many phenolic compds. (in addn. to tocopherols) are potential antioxidants: flavonoids, tannins and lignin precursors may work as ROS-scavenging compds. Antioxidants act as a cooperative network, employing a series of redox reactions. Interactions between ascorbic acid and glutathione, and ascorbic acid and phenolic compds. are well known. Under oxygen deprivation stress some contradictory results on the antioxidant status have been obtained. Expts. on overexpression of antioxidant prodn. do not always result in the enhancement of the antioxidative defense, and hence increased antioxidative capacity does not always correlate pos. with the degree of protection. Here, the authors present a consideration of factors which possibly affect the effectiveness of antioxidant protection under oxygen deprivation as well as under other environmental stresses. Such aspects as compartmentalization of ROS formation and antioxidant localization, synthesis and transport of antioxidants, the ability to induce the antioxidant defense and cooperation (and/or compensation) between different antioxidant systems are the determinants of the competence of the antioxidant system.
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    46. 46
      Tehrani-Bagha, A. R.; Kärnbratt, J.; Löfroth, J.-E.; Holmberg, K. Cationic ester-containing gemini surfactants: Determination of aggregation numbers by time-resolved fluorescence quenching. J. Colloid Interface Sci. 2012, 376, 126– 132,  DOI: 10.1016/j.jcis.2012.02.053
      46
      Cationic ester-containing gemini surfactants: Determination of aggregation numbers by time-resolved fluorescence quenching
      Tehrani-Bagha, A. R.; Kaernbratt, J.; Loefroth, J.-E.; Holmberg, K.
      Journal of Colloid and Interface Science (2012), 376 (1), 126-132CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
      The micellar aggregation no. of a series of ester-contg. gemini surfactants was detd. with steady state and with time-resolved fluorescence quenching. The latter method gave values of aggregation no. about twice those obtained with the former method. The length of the spacer was the most important factor affecting the aggregation no. The length and the nature of the surfactant alkyl chains were of less importance in spite of the fact that the length of the alkyl chains strongly affects the soln. properties of the unimers.
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    47. 47
      Rasool, K.; Helal, M.; Ali, A.; Ren, C. E.; Gogotsi, Y.; Mahmoud, K. A. Antibacterial Activity of Ti3C2T x MXene. ACS Nano 2016, 10, 3674– 3684,  DOI: 10.1021/acsnano.6b00181
      47
      Antibacterial activity of Ti3C2Tx MXene
      Rasool, Kashif; Helal, Mohamed; Ali, Adnan; Ren, Chang E.; Gogotsi, Yury; Mahmoud, Khaled A.
      ACS Nano (2016), 10 (3), 3674-3684CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      MXenes are a family of atomically thin, two-dimensional (2D) transition metal carbides and carbonitrides with many attractive properties. Two-dimensional Ti3C2Tx (MXene) has been recently explored for applications in water desalination/purifn. membranes. A major success indicator for any water treatment membrane is the resistance to biofouling. To validate this and to understand better the health and environmental impacts of the new 2D carbides, the authors investigated the antibacterial properties of single- and few-layer Ti3C2Tx MXene flakes in colloidal soln. The antibacterial properties of Ti3C2Tx were tested against Escherichia coli and Bacillus subtilis by using bacterial growth curves based on optical densities (OD) and colonies growth on agar nutritive plates. Ti3C2Tx shows a greater antibacterial efficiency toward both Gram-neg. E. coli and Gram-pos. B. subtilis compared with graphene oxide (GO), which has been widely reported as an antibacterial agent. Concn.-dependent antibacterial activity was obsd. and more than 98% bacterial cell viability loss was found at 200 μg/mL Ti3C2Tx for both bacterial cells within 4 h of exposure, as confirmed by colony forming unit (CFU) and regrowth curve. An antibacterial mechanism investigation by scanning and transmission electron microscopy coupled with a lactate dehydrogenase release assay indicated damage to the cell membrane, which resulted in release of cytoplasmic materials from the bacterial cells. Reactive oxygen species (ROS) dependent and independent stress induction by Ti3C2Tx was investigated in two sep. abiotic assays. MXenes are expected to be resistant to biofouling and to offer bactericidal properties.
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    • Structural formula and MS spectrum of BQAS; antibacterial activity of BQAS; zeta potential of bacteria; DNA strides of bacterial cells; ROS generation; intracellular superoxide levels; MICs of BQAS against different strains of bacteria (PDF)


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