Graphene Oxide

Graphene oxides (GO) have been used as DNA sensing platforms.

From: Design, Principle and Application of Self-Assembled Nanobiomaterials in Biology and Medicine, 2022

Chapters and Articles

Biopolymers-graphene oxide nanoplatelets composites with enhanced conductivity and biocompatibility suitable for tissue engineering applications

Biswadeep Chaudhuri, in Fullerens, Graphenes and Nanotubes, 2018

12.6.4 Fabrication of Thin Graphene Oxide Sheets and Hybrid Composite Materials With Biocompatible Polymers

The pure graphene oxide (GOnPs) sheet was obtained from graphene oxide hydrosol prepared by ultrasonic peeling of GOnPs in aqueous suspension. The solution was dried in a vacuum oven for making GOnP sheets by spin coating. Graphene oxide solution in water was applied to a 2 cm×2 cm clean glass slide or Teflon plate, which was mounted on a spin coater (Scientific India) attached with a local vacuum unit. The sample was spun at 1500 rpm for 20 s to fully cover the glass or Teflon slides with thin film composed of GOnPs. The sample was then placed inside a fume hood overnight before being placed in vacuum for complete evaporation of solvent and film formation (Chaudhuri et al., 2014b; Hummers and Offema, 1958). To prepare GOnPs-PCL or GOnPs-PLGA composites, the percolation threshold concentration of GOnPs-PCL and GOnPs-PLGA composites was studied. For this purpose, GOnP-polymer composite solutions were made in DMF (20 v/v%) and chloroform (80 v/v%) solutions with different GOnPs concentration (0–1 wt% GOnPs) and were treated with ultrasound for 45 min to make a homogenous brown dispersion. PLGA (50:50) (or PCL) was dissolved at ~80°C and the solution was subsequently cooled to room temperature (RT). The GOnPs were gradually added to the polymer solution (DMF, for PLGA) with stirring, and sonicated at RT for ~45 min to obtain homogeneous GOnPs/polymer solutions. Finally, these solutions were left to stand overnight to remove air bubbles, then poured into glass dishes and kept at ~40°C for film formation until its weight equilibrated (Chaudhuri et al., 2015). Similarly, GOnPs-PCL composite films of different GOnPs concentrations were prepared. The final disc-shaped composite films for different GOnPs concentrations were prepared, each having ~10–20 mm in diameter and ~0.1 mm in thickness. The concentrations of the GOnPs fillers were varied systematically to investigate the influence of GOnPs on the dielectric and electrical properties of the composite.

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128136911000129

Separations of Water Pollutants with Nanotechnology

C. Ursino, A. Figoli, in Separation Science and Technology, 2022

GO membranes preparation

Concerning the membranes containing GO, it is possible to divide them in three different types: (i) layered of nano-porous GO membranes; (ii) assembled laminated GO membranes; (iii) GO-composite membranes [122,126–128], represented in Fig. 7.

Fig. 7

Fig. 7. Main types of GO-based membranes.

Adapted from M. Sun, J. Li, Graphene oxide membranes: functional structures, preparation and environmental applications, Nano Today 20 (2018) 121–137. doi:10.1016/j.nantod.2018.04.007.

In the first case, GO sheets is perforated in order to form a nanopores. This is an ideal separation membrane, with a perfect structure and tunable pore size. Several works were reported in literature about the simulation performance of layer of nano-porous GO membranes [129–132]. The possibility to tune the nanopore size allows improving the membrane selectivity obtaining higher water permeability and salt rejection (approximately three orders of magnitude higher than some types of applied membranes, e.g., RO membranes) [126]. In terms of pore size, permeability and rejection, these properties would be perfect for the RO process; however, as reported by Petukhov et al. [127], to date, no experimental researches were developed to study the transport through this type of membrane. In the second type of GO membranes, the GO nanosheets were assembled in ordered laminated structures. GO membranes are GO paper-like selective and/or functional top layers onto porous supports. Basically, in this case it is possible to produce free-standing or supported membranes. These membranes were fabricated by deposition of a thin GO layer or GO nanocomposites (a few nm to μm) onto relatively thick support membranes (usually > 100 μm) [121]. Water flux (or general flux) takes place through the layered laminate GO membrane (interlayers nano-channels). These membranes possess a smaller pore size distribution and higher water permeability, up two orders of magnitude, with respect to the common UF membranes [126]. Several techniques were employed to prepare these membranes, as a different coating (spin-spray-dip-casting coating) [133], vacuum-assisted filtration [134], pressure-assisted methods [135], and casting processes. In the case of laminated structures, membranes performance is directly correlated to the interlayer distance [127]. Finally, the last case includes the MMMs where the GO was used as filler integrated with the polymer. These membranes were developed in order to improve the selectivity and permeability of polymeric material. As reported in literature [121], GO can migrate to the membrane surface during the PI, improving their hydrophilicity, porosity, and rejection.

Abdelkader et al. [136] prepared (GO)/polyacrylamide (PAM)/PES membrane, depositing GO on the PES surface via spin-coating technique and using PAM as an adhesive layer. GO was used at a higher concentration (5.5 mg/mL). Initially, a PAM solution (1.34 mg/mL) was spinning on the PES surface, and then GO solution was deposited over the membrane, increasing the rotation speed. PAM has been employed as a pretreatment step, to filter the divalent ions in desalination application. PA-GO composite membranes were prepared via pressure-assisted ultrafiltration with subsequent IP, using GO powder (0.2 g), by Zhao et al. [137]. PVDF-GO membranes were successfully prepared using a low toxic solvent via Nonsolvent-Induced Phase Separation (NIPS) and Vapor-Induced Phase Separation (VIPS)/NIPS, techniques [124]. GO was initially prepared starting from GN by means of its oxidation, and exfoliation by sonication. The obtained GO sheets possess a lateral size from 0.8 to 3.0 μm (most of them with thickness of 1.0 nm). Several amounts of GO (0–0.125–0.5 wt%) were directly incorporated in the polymeric dope solution and the influence of NIPS/VIPS preparation procedure and GO amounts was studied and evaluated. Layer-by-layer (LbL) assembly of positive chitosan (CS) and negative GO nanosheets via electrostatic interaction was employed to produce blending hydrophilic sulfonated polyethersulfone (SPES) into PES matrix via PI process [138]. GO nanosheets (0.1 wt%), previously prepared from graphene by Hummer's method, were dispersed in an aqueous solution at pH 10. The negatively charged SPES-PES porous substrate was initially firstly immersed in the CS polycation solution (pH 3) and then soaked in the GO solution. The alternative CS and GO treatment can be repeated to fabricate membranes with the desired number of CS/GO layers. Zinadini et al. [139] produced NF mixed matrix PES membranes using GO. Membranes were characterized in terms of morphology and performance on the dye removal, and the effect of the embedded GO NPs was evaluated. GO nanosheets were prepared from natural graphite by Hummer's method and subsequently several amounts were added in the dope solution (0–0.1–0.5–1 wt%). Membranes were then prepared via the PI method; the characterization results have been revealed an optimal GO concentration of 0.5 wt%, without agglomeration and pore-blocking due to high NPs concentration.

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780323907637000160

Carbon Nanomaterials

Jingjing Xu, Lei Wang, in Nano-Inspired Biosensors for Protein Assay with Clinical Applications, 2019

1.3.5 Graphene-Based Surface Plasmon Resonance (SPR) for Protein Assay

Graphene oxide composites can form biocompatible surfaces on sensing films based on surface plasmon resonance (SPR). Chiu et al. prepared a SPR biosensor based on a GO sheet bound to a specific peptide aptamer for detection of human hCG protein (see Fig. 1.24; Chiu et al., 2017b).

Figure 1.24. The GO–peptide-based SPR biochip experimental conditions. (A) The BK7 substrate deposited with a 2-nm chromium (Cr) adhesion layer and a 47-nm gold (Au) film. (B) The Au film was modified with a thiol self-assembled monolayer (SAM) of cystamine (Cys). (C) The fabrication of the GO sheets on the Au film. (D) The activation of the carboxyl end groups on the surfaces of the GO sheets. (E) A peptide aptamer probe was immobilized on the GO sheet surface using covalent bonds. (F) The unreacted carboxyl groups on the GO sheet surfaces were blocked by ethanolamine. (G) The target hCG proteins was captured by the peptide probe.

Reprinted from Chiu, N.-F., Kuo, C.-T., Lin, T.-L., Chang, C.-C., Chen, C.-Y., 2017b. Ultra-high sensitivity of the non-immunological affinity of graphene oxide-peptide-based surface plasmon resonance biosensors to detect human chorionic gonadotropin. Biosens. Bioelectron. 94, 351–357.

Chiu et al. constructed an immunosensor based on carboxyl-functionalized graphene oxide (GO-COOH) in SPR. Graphene which underwent carboxylation could adjust its visible spectrum, thereby improving and controlling plasma coupling mechanism (see Fig. 1.25; Chiu et al., 2017a).

Figure 1.25. (A) The molecular structure of carboxyl-functionalized GO sheet and its oxygen-containing groups. (B) The process of fabrication of SPR chip with bio-molecular immobilization on the surface of carboxyl-functionalized GO film.

Reprinted from Chiu, N.-F., Fan, S.-Y., Yang, C.-D., Huang, T.-Y., 2017a. Arboxyl-functionalized graphene oxide composites as SPR biosensors with enhanced sensitivity for immunoaffinity detection. Biosens. Bioelectron. 89, 370–376.
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128150535000015

Odorant Binding and Chemosensory Proteins

Patrik Aspermair, ... Wolfgang Knoll, in Methods in Enzymology, 2020

2.1.5 Fabrication of reduced graphene oxide FET

Following the cleaning and silanization of the surface with APTES, 20 μL of aqueous GO solution with a final concentration of 12.5 μg/mL are drop casted onto the IDE. The deposition of GO and the chemical reduction process is shown in Fig. 4.

Fig. 4

Fig. 4. The deposition of GO onto IDE starts with a self-assembly monolayer of APTES on the glass interlayer to insure good adhesion of the negatively charged GO suspension. Subsequently, an aqueous GO solution with 12.5 μg/mL is drop casted onto the IDE. After a rinsing and baking step for 1 h at 120 °C, the GO is reduced to rGO in hydrazine vapor for 4 h. A thermal reduction afterward increases the stability of the rGO gFET.

2.1.5.1 Preparation of GO solutions

GO used for the deposition on the interdigitated electrodes was provided from the University of Bayreuth (Feicht et al., 2017). The stock concentration of the GO solution is 4.28 mg/mL. Four different dilutions were prepared to determine the influence of the GO concentration on the transfer of IDE: 50, 25, 12.5 and 6.25 μg/mL in deionized H2O. After the measurements with the produced gFETs, the optimized concentration of 12.5 μg/mL was used to produce gFETs.

2.1.5.2 GO drop casting

The GO suspensions are applied by a drop cast method onto the chips. For this, a drop of 15 μL of GO suspension is pipetted onto the interdigitated electrodes of the chips, allowing the GO flakes to attach to the APTES layer for 2 h precisely. The time is very crucial to form a uniform layer on the sensing area. Subsequently, the excess GO suspension is rinsed off with deionized H2O, not directing the jet onto the array area and carefully blow drying with compressed air.

2.1.5.3 Reduction of graphene oxide

2.1.5.3.1 Hydrazine reduction

All GO-modified IDE chips are placed in the center of a glass Petri dish for chemical reduction. Because of the carcinogenic properties of hydrazine, it is important to work under the fume hood at all times and treat the waste with special care. 1 mL of hydrazine is pipetted into the corners of the glass dish, while the chips are all placed in the center. Immediately, the lid is sealed air-tight with Kapton tape right afterward and the dish is placed in the oven inside the fume hood at 80 °C for 4 h.

After reduction, the Petri dish remains in the fume hood without lid for 1 h to evaporate the remaining hydrazine before rinsing each chip with dH2O and subsequently with isopropanol to remove hydrazine residues. Gently blow-dry and store the chips in a desiccator or directly perform the thermal reduction.

2.1.5.3.2 Thermal reduction

For the thermal reduction, IDE chips are placed in a pre-heated oven at 200 °C under vacuum for 2 h. This leads to a more stable and reliable electrical chip performance. The chips are taken out of the oven after 2 h and cooled down to room temperature. The resistance of the chips is measured with a Fluke multimeter immediately after reduction. The chips are stored in a desiccator under vacuum until further functionalization and measurement.

2.1.5.3.3 Optimize GO concentration

GO concentration of 4.28 mg/mL in dH2O is too high for the deposition of monolayer GO on the surface, therefore it needs to be diluted. To optimize the properties of the rGO field-effect transistors, different GO solutions were deposited on the substrate. The criteria for a good field-effect transistor for bio-sensing are manifold:

Flakes need to connect the drain- with the source electrodes

Presence of semiconductive properties (transfer characteristic)

Single- or few-layered GO deposition

High mobility of the finally produced gFET

Linear dependency to environmental changes (pH, ionic strength)

Low ohmic resistance to avoid gate leakage current

Four different concentrations were drop cast on the gFET and judged according to these criteria.

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/S0076687920302494

Enzyme Nanoarchitectures: Enzymes Armored with Graphene

Nalok Dutta, Malay K. Saha, in Methods in Enzymology, 2018

4.9 Stability and Reusability of GO-Lip

GO-lip could be reused for 12 repeated times retaining significant activity at both lower (71.17%; 45°C) and higher (76.4%; 95°C) temperatures whereas free lipase lost ~ 50% of activity after single use at 95°C (Fig. 4B and C). At 45°C, the free lipase lost its residual activity gradually after the third cycle retaining ~ 33% of its initial activity after the sixth use. GO immobilization of lipase via glutaraldehyde as crosslinker imparted flexibility to the temperature range for the enzyme activity. GO-lip could be stored at 4°C for more than 160 days with the enzyme retaining 79% activity whereas the free lipase could only retain 45% of its activity at the same temperature after 80 days (Fig. 4D).

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/S0076687918302064

Enzyme Nanoarchitectures: Enzymes Armored with Graphene

Orr Schlesinger, Lital Alfonta, in Methods in Enzymology, 2018

2.5.2 Filtration–Evaporation Method for Carbon Cloth–GO Electrode Fabrication

As GO hydrogel is a soft and flexible material it enables the generation of paper or foil-like electrodes that can be used as chemical filters, battery or electrical components, flexible biosensor electrodes, etc. (Dikin et al., 2007; Li, Müller, Gilje, Kaner, & Wallace, 2008). Carbon cloth is a good scaffold for a GO-based electrode because it reinforces the hydrogel while maintaining its flexibility, thermal, and electrical conductivity. Microorganisms, enzymes, and small molecules can be encapsulated in GO to create a biocatalytic electrode with high selectivity, specificity, and efficiency (Ravenna, 2015) (Fig. 3). Below is a modified version of the GO paper preparation protocol from Dikin et al. (2007).

Equipment

Vacuum filtration apparatus with sintered glass as support (such as Starlab Scientific product # SLGSF05002)

Vacuum pump

Buffers and reagents

Hydrophilic carbon cloth (ELAT®) (e.g., Fuel cell store product # 1591002)

Polyvinylidene difluoride (PVDF) membrane (0.2 μm pore size)

1% w/v GO suspension (can also be achieved with GO suspension containing enzymes, mediators, bacteria, or yeast cells)

Procedure
1.

Assemble the filtration apparatus.

2.

Cut the PVDF membrane to size and place onto the sintered glass (47 mm diameter).

3.

Place the hydrophilic carbon cloth on the PVDF membrane and carefully pour 10 mL of the GO suspension (composite GO suspension with microorganisms, enzymes, or mediators may also be used).

4.

Connect the vacuum pump.

5.

Leave the vacuum on for approximately 12 h, until the film is dry.

6.

Peel off and remove the carbon cloth—GO composite from the filtration apparatus.

Notes

Standard, untreated carbon cloth can be treated for increased hydrophilicity. Incubate the carbon cloth in concentrated nitric acid (HNO3) at 90°C for 1 h (Warning: warm concentrated nitric acid is extremely corrosive! work with coaution). Then wash the carbon cloth thoroughly with water and dry at 60°C for 24 h. Keep in a desiccator until use. Other methods for carbon cloth treatment can be found in Polovina, Babić, Kaluderović, and Dekanski (1997).

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/S0076687918302052

Functionalized Carbon Nanomaterials for Biosensors

Bansi Dhar Malhotra, Md. Azahar Ali, in Nanomaterials for Biosensors, 2018

2.4.0 Graphene, Graphene Oxide, and Reduced Graphene Oxide for Biosensors

Graphene, GO, rGO, and other graphene derivatives such as chemically modified graphene, thermally modified have been proposed for application to biosensors [9]. Although the pristine graphene sheets have superior conductivity, their limited applications in biosensors have been found to be due to their functionality for attachment of biomolecules. To realize a suitable nanobiointerface of graphene with biomolecules, graphene can be chemically exfoliated from graphite oxide by oxidation or by mechanical or thermal exfoliation of graphite oxide to GO sheets. GO sheets are known to be hydrophilic, and can be oxygenated to obtain graphene sheets. Because of the presence of oxygenated functional groups and a specific 2D structure, GO shows excellent properties such as electronic, optical, mechanical, thermal, and chemical reactivity for application to biosensors and medical devices [38]. The conductivity of GO depends on its chemical and atomic structures because of the degree of structural disorder arising due to substantial sp3 carbon fraction. GO-based films are found to be insulating in nature with a sheet resistance around 10 Ω/sq. The insulating nature of GO can be linked to the concentration of sp3 Csingle bondO bonds resulting in a decrease of electrons transfer and leading to the disruption of percolating pathways with sp2 carbon clusters. The removal of oxygenated groups or reduction of GO by chemical or thermal treatments can facilitate the transport of carriers resulting in a decrease of Rs by several orders of magnitude and thus transforms the insulting GO into a semiconductor or graphene-like semimetal. The conductivity of the reduced GO sheets has been found to be ∼1000 S/m.

The non-functionalized pristine graphene is known to be insoluble in any solvent. It can however, be deposited on the substrate by mechanical cleavage, known as the “scotch-tape” method, resulting in uncontrollable shape, size, and location. The CVD technique was employed for deposition of controlled layer of graphene. A graphene-based FET (GFET) on flexible polyethylene terephthalate substrate used as biosensor in aqueous solution is shown in Fig. 2.3.0 [39]. The graphene channel can be buried in a flow cell or sensing chamber, and the GFET device was found to operate in an aqueous environment to detect biospecies. The drain and source need to be insulated to avoid current leakage due to ionic conduction, and the Ag/AgCl or Pt (gate electrode) is immersed in the solution. An electric double layer capacitance arises at channel–electrolyte interface due to applied gate potential. GFET device, the electrostatic gating effect and the doping effect are two major sensing mechanisms that have been explored. In the gate, the charged molecules are adsorbed onto graphene that acts as an supplemental gating capacitance for changing the conductance of the graphene channel. In doping effect, a direct charge transfer can occur between the adsorbed biomolecules and the graphene channel. In a GFET device, graphene can be functionalized noncovalently via π–π or electrostatic interactions with biomolecules such as proteins, single-strand DNA (ssDNA), enzymes, etc. for biosensors development. For example, ssDNA was directly interfaced onto the graphene surface by incubation in the presence of phosphate-buffered saline to improve the biostability and specificity [40]. A sensitive FET has been developed by establishing a graphene–cellular interface to investigate electrogenic cells [41].

Figure 2.3.0. A solution-gate graphene field-effect transistor on flexible polyethylene terephthalate (PET) substrate used as a chemical and biological sensor in aqueous solution [39].

The presence of oxygen-containing functional groups (carboxyl, hydroxyl, or epoxy) provides potential benefits of GO sheets for numerous applications due to their multifunctionalities. N-Ethyl-N-(3-dimethylaminopropyl)-carbodiimide-N-hydroxysuccinimide (EDC-NHS) coupling mechanism is one of the most popular method that is utilized to covalently link proteins with the carboxyl groups of GO sheets. In this method, the amidation reactions allow the making of a covalent bond called amide (Csingle bondN) between the biomolecule and GO sheet resulting in enhanced stability and selectively of device. The antibody conjugates on the surface of aminated GO sheets using EDC-NHS chemistry to establish a suitable biointerface for investigations of lipid–lipid interactions [42]. Although GO shows poor conductivity, it provides excellent electron transfer behavior since it has been found to exhibit well-defined redox peaks via cyclic voltammetry (CV) studies in the presence of ferro/ferricyanide ([Fe(CN)6]3−/4−) and hexaammineruthenium(III/II) ([Ru(NH3)6]3+/2+), respectively [38]. It has been found that the magnitude of both the anodic and cathodic peak current in the CVs increases linearly with the square root of the scan rate suggesting that the redox processes on GO electrodes are diffusion controlled. Thus, GO is a potential candidate for fabrication of an electrochemical biosensor. Since most atoms at GO sheets are exposed to the surface, slight changes due to adsorption of protein molecules exhibit significant changes in their electrical properties that can be helpful for the fabrication of more sensitive biosensors. Papakonstantinou et al. first utilized graphene nanoflakes for electrochemical sensing of dopamine, ascorbic acid, and uric acid simultaneously [43]. GO has been recently used for development of electrochemical glucose sensor by covalent interactions of carboxyl acid groups of GO sheets with amines of glucose oxidase [44]. A PDMS–paper–glass-based microfluidic sensor integrated with aptamer-functionalized GO nanobiosensor has been demonstrated for simple, one-step and multiplexed pathogen detection (Fig. 2.3.1) [45]. An aptamer–carboxyfluorescein and GO nanosheet complex have been employed for molecular probing in living cells [46].

Figure 2.3.1. An aptamer-functionalized graphene oxide (GO)–based microfluidic biosensor using polydimethylsiloxane (PDMS)–paper hybrid for detection of multiplexed pathogens: (A) layout of microfluidic sensor, (B and C) the principle of the one-step “turn-on” detection method using interactions of GO, aptamers, and pathogens. (1: sensor fluorescence is quenched when an aptamer is adsorbed on the GO surface; and 2: with target pathogen, it induces the aptamer to be liberated from GO and thus restores its fluorescence for detection [45].)

The electrochemical conductivity of GO can be improved by the reduction of oxygenated functional groups by chemical or thermal techniques. The chemically rGO with a considerable amount of functional groups has been found suitable for the attachment of biomolecules with desired conductivity, resulting in many electrochemical sensing applications. The improved conductivity of rGO sheets has been found to be beneficial for development of electrochemical biosensors recently; electrophoretically deposited rGO sheets on ITO electrode for detection of aflatoxin B1 in food [47] and electrochemically active rGO utilized as immunosensing platform for ultrasensitive detection antigen [48]. A label-free, highly sensitive, reproducible, and selective immunosensor has been reported using anti-apolipoprotein B functionalized mesoporous few-layer rGO and nickel oxide (rGO–NiO) composite for quantification of low-density lipoprotein molecules (Fig. 2.3.2) [49]. rGO can be utilized for development of enzymatic biosensors without mediators for the fabrication of the third-generation amperometric glucose biosensors via direct electron transfer mechanism [50]. Quantum dots and rGO composite have recently been utilized for bioimaging of tumor cells with photothermal therapy [51].

Figure 2.3.2. Functionalization of reduced graphene oxide (rGO)–NiO composite with antibody for detection of blood low-density lipoprotein (LDL) molecules [49].

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780323449236000029

Application of Carbon-Based Nanomaterials as Drug and Gene Delivery Carrier

Sekhar Chandra Ray, Nikhil Ranjan Jana, in Carbon Nanomaterials for Biological and Medical Applications, 2017

5.3.3.2 Graphene Oxide in Drug Delivery

GO, produced by vigorous oxidation of graphite by Hummers method (1958), is an ideal nanocarrier for efficient drug and gene delivery. GO used for drug delivery is usually one to three layers (1–2 nm thick) with size ranging from a few nanometers to several hundred nanometers (Loh et al., 2010; Kovtyukhova et al., 1999; Sun et al., 2008). The unique structural features, such as large and planar sp2 hybridized carbon domain, high-specific surface area (2630 m2 g−1), and enriched oxygen-containing groups, render GO excellent biocompatibility, physiological solubility and stability, and capability of loading of drugs or genes via chemical conjugation or physisorption approaches. Moreover, the reactive COOH and OH groups GO bears facilitate conjugation with various systems, such as polymers (Shan et al., 2009), biomolecules (biotargeting ligand (Sun et al. 2008), DNA (Lei et al., 2011), protein (Zhang et al., 2010a,b,c, 2011; Lee et al., 2011), quantum dots (Dong et al., 2010), Fe3O4 nanoparticles (Chen et al., 2011a,b), and others (Shen et al., 2010) imparting GO with multifunctionalities and multimodalities for diverse biological and medical applications.

Inspired by the ideas for carbon nanotube-based drug delivery (Liu et al., 2011a,b), Dai et al. explored NGO for the first time as a novel and efficient nanocarrier for delivery of water-insoluble aromatic anticancer drugs into cells (Liu et al., 2008a,b,c). In their approach, NGO was first conjugated with an amine-terminated six armed PEG molecule, followed by loading of a water-insoluble anticancer drug, SN38, onto NGO surface by simple noncovalent adsorption via π–π stacking. The PEG-functionalized NGO loaded with SN38 exhibited high cytotoxicity for HCT-116 cells is 1000-fold more potent than CPT-11. In another work, the same group studied targeted delivery of chemical drugs into cells by using a Rituxan (CD20+ antibody)-conjugated NGO–PEG (Sun et al. 2008) (Fig. 5.4). It was further demonstrated that the drug releases from the GO surface was pH dependent, suggesting the possibility of pH-controlled drug release. The pH-sensitive drug release behavior from many different GO-based drug delivery systems was also studied later by Yang et al. (2008a,b,c), Bai et al. (2010), Depan et al. (2011), Zhang et al. (2010a,b,c). Apart from pH-activated drug release, Pan et al. (2011) developed a thermoresponsive drug delivery cargo, PNIPAM-grafted graphene sheets.

Figure 5.4. Nanographene oxide (NGO) for target cell imaging and drug delivery. (A) A schematic illustration of doxorubicin (DOX) loading onto NGO-PEG-Rituxan via π-stacking. Atomic force microscopy images of as-prepared (B) graphene oxide (GO) and (C) NGO-PEG. Near-infrared (NIR) fluorescence image of (d) CD20-positive Raji B-cells and (E) CD20-negative CEM cells treated with the NGO-PEG-Rituxan (anti-CD20 antibody) conjugate. Scale bar shows intensity of total NIR emission in the range of 1100–2200 nm under the 785 nm excitation. Scale bar = 25 μm. (F) In vitro toxicity test at 2 μM and 10 μM DOX concentrations showing that Rituxan conjugation selectively enhanced DOX delivery into Raji B-cells by comparing NGO-PEG-Rituxan/DOX with free DOX; NGO-PEG/DOX; and the mixture of DOX, Rituxan, and NGO-PEG (Sun et al., 2008). PEG, polyethylene glycol.

Reproduced with kind permission from Springer Science @ Business Media and Tsinghua Press.

Combined use of multiple drugs is a widely adopted clinical practice in cancer therapy to overcome drug resistance of cancer cells (Andersson et al., 1999; Gavrilov et al., 2005). However, few reports on nanomaterial-based drug delivery systems for controlled loading and delivery of multiple drugs can be found in the literature due to technical difficulties. Zhang et al. (2010a,b,c) explored the feasibility of GO as a nanocarrier for controlled loading and targeted delivery of mixed chemical drugs. Rana et al. (2011) reported the delivery of an antiinflammatory drug, ibuprofen, by using a chitosan-grafted GO. In this case, the loading rate of ibuprofen on the GO sheet was determined to be 9.7%. Furthermore, the work demonstrates that controlled drug release can be achieved by adjustment of pH value.

To enhance the anticancer effect, Yang et al. (2011) designed and prepared a magnetic- and bio-dual targeting drug delivery cargo based on GO-Fe3O4 nanoparticle hybrid. The in vitro experiments indicated specific targeting of the multifunctional drug carriers by SK3 human breast cancer cells. Clearly, in vivo study is desired to demonstrate the performance of this external magnetic field–guided and biotargeted drug delivery system.

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780323479066000059

Carbon nanotubes and graphene nanomaterials for biomedical applications

Ritu Painuli, ... Dinesh Kumar, in Design, Principle and Application of Self-Assembled Nanobiomaterials in Biology and Medicine, 2022

13.3.2.1 Graphene oxide as biosensors

GO possesses the capability to transduce a definite reaction to the target moiety and extraordinarily relate to the probe. The transduction can be accomplished via electrochemical reaction, Raman scattering, and fluorescence. Hence, graphene materials are generally employed in the field of biosensing [71]. Reduced graphene nanowire as the biosensors was reported by Akhavan and coworkers for the electrochemical detection of DNA [72]. Cheng coworkers prepared carboxylic group functionalized GO along with polyaniline changed GO. The prepared GO effectively detected DNA via differential pulse voltammetry [73]. Based on the graphene field-effect transistors, label-free DNA biosensors were prepared. The prepared biosensors depict a wide analytical range and offer the outlook of figuring out the DNA hybridization and sequencing more accurately and rapidly [74]. Liu coworkers informed biocompatible GO-based glucose sensors. The biosensor was prepared by the covalent bonding between -COOH groups of GO sheets and amines of glucose oxidase [75]. A biosensor based on enzymatic GO decorated tilted fiber grating was reported for the detection of glucose. A GO layer wrapped on a tilted fiber grating surface was used as a matrix for the covalent immobilization of glucose oxidase. The biosensor was used for the detection of glucose, even at low concentrations [76]. A GO-based biosensor can be employed in the diagnosis of a disease like typhoid. Singh et al. prepared a GO/Chitosan nanocomposite to develop a DNA-based electrochemical biosensor to diagnose typhoid. The satisfactory results observed from the prepared biosensor are credited to the enhanced surface area and electrochemical activity of GO, along with the excellent biocompatibility of chitosan [77].

Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780323909846000052

Recent advances of graphene family nanomaterials for nanomedicine

Irina Negut, ... Emanuel Axente, in Fullerens, Graphenes and Nanotubes, 2018

11.3.2.1 Noncovalent functionalization of graphene family nanomaterials

GO can also be noncovalently functionalized by biomolecules and/or polymers (by π–π stacking, cation-π, van der Waals force or bindings) (Xing and Dai, 2009; Krueger, 2008). Table 11.1 lists different GFN noncovalent formulations proposed. This type of functionalization can be achieved through sp2 networks that are not involved in the hydrogen bonding or oxidized. Briefly, it consists of GFN coating with amphiphilic molecules, usually to increase their stability in aqueous solutions. In the case of biomedical applications, the biocompatibility of GFN can be increased by using some proteins, such as gelatin (Liu et al., 2011a,b) or polymers such as polyethylenimine (Feng et al., 2011). The main distress of noncovalent functionalization is represented by the low stability of noncovalent conjugates.

Table 11.1. Examples of Typical Noncovalent Functionalization GFN Used for Biomedical Applications

Methods/Mechanisms Substance References
π–π Stacking interaction Pyridine Chen et al. (2014)
Quinoline Kim et al. (2015)
Anthracene Khanra et al. (2015)
Ionic liquids Jiang et al. (2014), Bozkurt et al. (2014)
van der Waals force Cellulose Carrasco et al. (2014)
Electrostatic Fetal bovine serum Hu et al. (2011)
Hydrogen bonding Methylacrylic acid Liu et al. (2016)
Benzidine Vermisoglou et al. (2017)
Ye-labeled ssDNA Lu et al. (2009)
Coordination bonding Tetraazamacrocyclic complexes of nickel(II) Basiuk et al. (2016)
Metallophthalocyanine Kang et al. (2017)
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128136911000117