Polymeric-patterned surfaces are finding significant importance in various biomedical application... 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.
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitt... 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.
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitt... 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...
The eminence of nano-scale materials prevailed after the invention of high-resolution microscopes... 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...
Nanosensors have been proven to be a powerful tool in sensing various targeting analytes such as ... 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...
Copper-DTDTPA adsorbed on filter paper shows solid electrolyte behavior for its application in so... more Copper-DTDTPA adsorbed on filter paper shows solid electrolyte behavior for its application in solid state oxygen gas sensors.
Flow of water in a gold-nanoparticle-embedded microchannel power generator generated a power dens... more 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.
The need for the removal of salt constituents is very critical in several downstream processes of... 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.
In this work, a bright red fluorescent protein-capped gold nanocluster, AuNC@BSA, is developed in... 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...
Functionalization of gold nanorod (GNR) with dimercaptosuccinic acid is reported as a way to deve... 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...
Polymeric-patterned surfaces are finding significant importance in various biomedical application... 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.
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitt... 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.
A novel approach used to synthesize antimetabolite-conjugated and intense blue fluorescence-emitt... 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...
The eminence of nano-scale materials prevailed after the invention of high-resolution microscopes... 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...
Nanosensors have been proven to be a powerful tool in sensing various targeting analytes such as ... 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...
Copper-DTDTPA adsorbed on filter paper shows solid electrolyte behavior for its application in so... more Copper-DTDTPA adsorbed on filter paper shows solid electrolyte behavior for its application in solid state oxygen gas sensors.
Flow of water in a gold-nanoparticle-embedded microchannel power generator generated a power dens... more 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.
The need for the removal of salt constituents is very critical in several downstream processes of... 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.
In this work, a bright red fluorescent protein-capped gold nanocluster, AuNC@BSA, is developed in... 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...
Functionalization of gold nanorod (GNR) with dimercaptosuccinic acid is reported as a way to deve... 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...
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