Polymeric-patterned surfaces are finding significant importance in various biomedical applications such as screening and diagnostic assays, tissue engineering, biosensors, and in the study of fundamental cell biology. A wide variety of... more
Polymeric-patterned surfaces are finding significant importance in various biomedical applications such as screening and diagnostic assays, tissue engineering, biosensors, and in the study of fundamental cell biology. A wide variety of methods, involving photolithography, inkjet printing, soft lithography, and dip-pen lithography, have emerged for protein or polymer patterning on various substrates. For directional immobilization or adsorption of protein, surface requires pre-defined regions to which protein molecules can be immobilized. The most common techniques to introduce defined protein immobilization are soft lithography and photolithography. However, these techniques have some associated limitations. In soft lithography, stamps with well-defined structures are required, and the migration of ink during and after printing needs to be well controlled. In photolithography, a polymeric photoresist and a mask are needed which require expensive setup to fabricate. Therefore, facile and economic techniques are worth exploring. The dewetting of a thin polymeric film is a spontaneous and self-organized process that forms an array of microscale and nanoscale droplets on a substrate. This is a facile approach of patterning polymer on glass substrate providing a reliable surface for specific, dense, and uniform immobilization of desired molecules to pre-designed patterns. Since antibody orientation is very important in antibody-based surface capture assays, patterned polymer surfaces are of great importance with respect to an increasing number of biosensor applications. Apart from protein patterning, such polymeric-patterned surface can be effectively used in specific type of cell isolation and detection. Indeed, it is found that circulating tumor cells (CTCs) are easily isolated using such patterned structures either on a flat plate or inside a microfluidic environment.
Research Interests:
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitting smart polymeric nanoparticles is reported for the efficient delivery of anticancer drugs and self-monitoring their effect in... more
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitting smart polymeric nanoparticles is reported for the efficient delivery of anticancer drugs and self-monitoring their effect in drug-resistant metastatic breast cancer cells.
Research Interests:
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitting smart polymeric nanoparticles is reported for the efficient delivery of anticancer drugs and self-monitoring their effect in... more
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitting smart polymeric nanoparticles is reported for the efficient delivery of anticancer drugs and self-monitoring their effect in drug-resistant metastatic breast cancer cells. Metastatic breast cancer is the deadliest cancer in women as chemotherapy does not perform well in its treatment. To prepare the drug-loaded fluorescent nanoparticles, the FDA-approved non-fluorescent poly(D,L-lactide-co-glycolide) (PLGA) polymer was modified into a newly designed fluorescent PLGA polymer by the covalent conjugation of the biocompatible fluorophore 1-pyrenebutyric acid (PBA). The fluorescent PLGA–PBA polymer was then electrosprayed by applying a potential of 8.0 kV to synthesize mono-dispersed spherical fluorescent nanoparticles (size ∼40 nm). The surface of the PLGA–PBA nanoparticles was conjugated with the potent anticancer drug molecule methotrexate (MTX) through a linker molecule, ethylenediami...
Research Interests:
The eminence of nano-scale materials prevailed after the invention of high-resolution microscopes. Nowadays, nanoparticles are predominantly found in every application, including biomedical applications. In nanomedicine, the unique... more
The eminence of nano-scale materials prevailed after the invention of high-resolution microscopes. Nowadays, nanoparticles are predominantly found in every application, including biomedical applications. In nanomedicine, the unique properties make nano-scale...
Research Interests:
Research Interests:
Nanosensors have been proven to be a powerful tool in sensing various targeting analytes such as proteins, DNA, and RNA and small molecules such as toxins, drugs, metabolites, biomarkers, and environmental pollutants with high specificity... more
Nanosensors have been proven to be a powerful tool in sensing various targeting analytes such as proteins, DNA, and RNA and small molecules such as toxins, drugs, metabolites, biomarkers, and environmental pollutants with high specificity and selectivity. Among various environmental pollutants, pollution by contamination of heavy metal is one of the most serious issues in current global scenario because of its potential toxicity toward human and aquatic life. Conventional methods of detecting such toxic ions include inductively coupled plasma mass spectroscopy (ICP-MS) and atomic absorption spectroscopy (AAS). These methods are accurate in minute-level detection, but still possess some drawbacks such as high time consumption, involvement of toxic chemicals, and requirement of sophisticated laboratory setup. Therefore, there is a need for inexpensive, user-friendly, quick, and portable methods for detection of these toxic ions. Efforts are being made in developing gold nanosensors fo...
Research Interests:
Copper-DTDTPA adsorbed on filter paper shows solid electrolyte behavior for its application in solid state oxygen gas sensors.
Research Interests:
Research Interests:
Research Interests:
Flow of water in a gold-nanoparticle-embedded microchannel power generator generated a power density of 4.3 μW cm−2, a value ∼256 times higher than that last reported.
Research Interests:
Research Interests:
Research Interests:
The need for the removal of salt constituents is very critical in several downstream processes of biological materials and saltwater purification. Substantial efforts to drive low cost-effective techniques for desalination are ongoing,... more
The need for the removal of salt constituents is very critical in several downstream processes of biological materials and saltwater purification. Substantial efforts to drive low cost-effective techniques for desalination are ongoing, and it is hopeful that novel nanomaterials could provide useful insight to a new paradigm in salt capturing both in biogenic fluids and complex solutions like seawater. In this report, we demonstrate a microfluidic proof-of-concept for a desalination system, in which graphene oxide deposited on the paper substrate was used to remove salt-ion concentration. Our investigation suggests that the optimal modification of paper with the five-time deposition of graphene oxide (paper@5GO) shows the best salt removal performance with the salt-rejection efficiency of ~ 97.0%. The salt rejection occurs by the phenomenon of surface adsorption on the GO-modified paper membrane which is confirmed by the detailed analytical studies of pre- and post-treatment. The system presented does not require additional energy input in the process and thus would become cost-effective and scalable with high salt removal efficiency which may be useful in bioanalysis and saltwater purification for sustainable development.Graphical abstractWe demonstrate a microfluidic proof-of-concept for a desalination system, in which graphene oxide deposited on the paper substrate is used for the salt-rejection purpose that may be useful in bioanalysis and saltwater purification for sustainable development.
Research Interests:
In this work, a bright red fluorescent protein-capped gold nanocluster, AuNC@BSA, is developed in a green synthesis approach, and its application as a sensor for detection of Pb(II) ion in water and in live cells is demonstrated. AuNC@BSA... more
In this work, a bright red fluorescent protein-capped gold nanocluster, AuNC@BSA, is developed in a green synthesis approach, and its application as a sensor for detection of Pb(II) ion in water and in live cells is demonstrated. AuNC@BSA is prepared by dithiothreitol (DTT)-mediated activation of bovine serum albumin (BSA) followed by the reduction of HAuCl4 in an aqueous medium. The incorporation of DTT assists in the reduction of disulfide bridges present in cysteine residues, which in turn increases the reducing power of BSA forming a significant number of the Au25 clusters that enhances the bright red fluorescence of AuNC@BSA at 660 nm when excited at 520 nm with a highest quantum yield of ∼20.0% reported so far. AuNC@BSA as nanosensor selectively detect Pb(II) ion in water with a detection limit of 1.0 ppb, lower than the World Health Organization limit (10.0 ppb), and follow quenching-based sensing mechanism through metallophilic interaction between Au(I) and Pb(II) ion. In presence of a strong chel...
Research Interests:
Research Interests:
Research Interests:
Functionalization of gold nanorod (GNR) with dimercaptosuccinic acid is reported as a way to develop a sensor, GNR-PEG-DMSA that can rapidly detect very low concentrations of arsenic contamination in water and using the paper strip. The... more
Functionalization of gold nanorod (GNR) with dimercaptosuccinic acid is reported as a way to develop a sensor, GNR-PEG-DMSA that can rapidly detect very low concentrations of arsenic contamination in water and using the paper strip. The sensor is developed by stepwise chemical conjugations of gold nanorods (GNR) with poly(ethylene glycol) methyl ether thiol (mPEG-SH) followed by meso-2,3-dimercaptosuccinic acid (DMSA). GNR-PEG-DMSA shows a visible color change in the presence of both inorganic forms of arsenic: AsIII (arsenite) and AsV (arsenate) ions in solution and on a paper substrate, because of the ion-induced aggregation of nanorods through an arsenic complex formation strategy, which is relative to the arsenic concentrations. Colorimetric and spectroscopic analyses are very much selective for both AsIII and AsV ions with a detection limit of ∼1.0 ppb. In addition, the GNR-PEG-DMSA exhibits excellent potential for quantitative estimation of total arsenic in groundwater samples. The paper-based sensi...
Research Interests:
A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is... more
A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is used to develop a thin film over a clean glass substrate which dewets spontaneously in the micro-/nano-patterned surface of size range 50nm to 3.5µm. Since another water-soluble polymer, poly vinyl alcohol (PVA) is coated on the same glass substrate before PLGA thin film formation, developed micro-/nano-patterns are easily extracted in water in the form of micro- and nanoparticle mixture of size range 50nm to 3.0µm. This simplified method is also used to effectively encapsulate a dye molecule, rhodamine B inside the PLGA micro-/nanoparticles. The developed dye-encapsulated nanoparticles, PLGA-rhodamine are separated from the mixture and tested for in-vitro delivery application of external molecules inside human lung cancer cells. For the first time, ...
Research Interests:
Mixed copper nanocomposite, Cu/CuO–rGO is prepared through a novel one-step oxidation-reduction reaction between aqueous graphene oxide (GO) and copper(ii) chloride (CuCl2) solutions at ambient temperature and pressure.
Research Interests:
The functionalities of a paper-PDMS hybrid microchannel, as a potential fluidic transport platform, are presented. The setup consists of a PDMS microchannel with one of its walls covered by paper. In contrast to the available microfluidic... more
The functionalities of a paper-PDMS hybrid microchannel, as a potential fluidic transport platform, are presented. The setup consists of a PDMS microchannel with one of its walls covered by paper. In contrast to the available microfluidic platforms, the capillary filling is found to occur at much faster speed in the hybrid channel. Moreover, experimentation using two dye solutions shows mixing enhancement at a significantly faster rate and at a shorter distance in the hybrid channel as compared to the other available counterparts. The paper attachment is found to induce an effective slip during liquid transport, and thereby allows faster transport and capillary filling. The liquid slippage further modifies the shear flow behavior near the wall leading to a slip-enhanced mixing within the hybrid channel. These fundamental understandings correspond to the experimental results quantitatively in terms of corroborating scaling laws. Further mixing enhancement is introduced through spiral, curved and elliptical–spiral geometries of the channel. Apart from the above benefits, the enclosed arrangement protects sensitive reagents from external environment and offers better control over their transport, thus giving a stable mixing and reaction performance inside the channel.
Research Interests:
ABSTRACT Paper based electro-kinetics is a new approach to drive the fluids through it at faster rates as comparison to low flow rates observed via capillary action mechanism due to pores present in the fibres. In the present study we... more
ABSTRACT Paper based electro-kinetics is a new approach to drive the fluids through it at faster rates as comparison to low flow rates observed via capillary action mechanism due to pores present in the fibres. In the present study we studied electro-kinetically driven fluid movement on a paper-pencil based microchannel under high electric field (0-10 kV). Since electrophoresis under high voltage range is a new research endeavour to separate nanoparticles, drug molecules and biomolecules, patterning of liquid films, to name a few. Herein, we studied capillary driven movement of nanoparticles on a paper-pencil device fabricated by CO2 laser engraving method.The Hb pencil has been used to mark the electrodes at the paper substrate. Further more Rhodamine dye molecules movement through the paper in high voltage range is observed as well.In addition we have also demonstrated the movement of gold nanoparticle based sensor for arsenic detection. The proposed method enables us to not only detect the arsenic on paper based chips but to remove the arsenic from the system very fast and easily. In this method citrate stabilized gold nanoparticles were prepared using HAuCl4 as precursor gold salts. Ruby red colored gold nanoparticles were further modified with thioctic acid which can be used to detect arsenic ion present in various samples by the change of color from red to blue.
Research Interests:
A smart gold nanosensor, Au–TA–DNS is designed that can rapidly detect very low concentrations of Pb2+ and Cu2+ ions.
Research Interests:
We report a new method for the fabrication of flexible supercapacitor electrodes wherein mechanically exfoliated graphite on paper containing gold nanoparticles is used as supercapacitor electrodes. It has been found that the... more
We report a new method for the fabrication of flexible supercapacitor electrodes wherein mechanically exfoliated graphite on paper containing gold nanoparticles is used as supercapacitor electrodes. It has been found that the supercapacitor electrode made of paper containing gold nanoparticle with graphite exfoliation yields a capacitance, which is about 4.3 times higher than that of the electrodes without gold nanoparticles.
Research Interests:
A series of dinuclear complexes [{(L1–4)ClRuII}2(μ-tppz)][ClO4]2 {[1](ClO4)2 to [4](ClO4)2} has been prepared, in which two {RuII(L1–4)Cl}+ fragments [L = a 2-arylazopyridine ligand of the type 2-(C5H4N)–NN–C6H4R; for L1, R = H; L2, R =... more
A series of dinuclear complexes [{(L1–4)ClRuII}2(μ-tppz)][ClO4]2 {[1](ClO4)2 to [4](ClO4)2} has been prepared, in which two {RuII(L1–4)Cl}+ fragments [L = a 2-arylazopyridine ligand of the type 2-(C5H4N)–NN–C6H4R; for L1, R = H; L2, R = p-Me; L3, R = p-Cl; L4, R = m-Me] are linked by the bridging ligand tppz [2,3,5,6-tetrakis(2-pyridyl)pyrazine]. A single isomer forms during the synthesis in each case, and the crystal structure of [4](ClO4)2 shows it to be a twofold-symmetric isomer with each ligand L arranged such that its pyridine donor is on the long axis of the molecule (trans to the pyrazine ring of tppz) and the azo donor is trans to one of the pyridyl donors of tppz. This allows the peripheral aryl ring attached to the azo unit of each ligand L to be oriented over either face of the bridging ligand giving a three-layer π-stacked (aryl–pyrazine–aryl) sandwich. Electrochemical studies revealed (i) separations of 190–250 mV (depending on the aryl substituent of L) between the successive Ru(II)/Ru(III) couples, indicative of a significant inter-metallic electronic coupling, and (ii) several ligand-based reductions of the π-acceptor pyrazine and arylazopyridine ligands. A UV/Vis/NIR spectroelectrochemical study showed the presence of an IVCT transition at ca. 1900 nm in MeCN for the Ru(II)–Ru(III) mixed-valence states, whose narrowness is indicative of borderline class III behaviour. Several reduced forms of the complexes were also spectroscopically characterised.