I am a Ph.D research scholar from Indian Institute of Technology Roorkee. I am working in the field of Optical sensors for sensitive detection of biomolecules and further development of point of care platforms for on field applications. I have used optical spectroscopic techniques to develop sensors for the detection of Nitroaromatic compounds in the past. I have also expertise in 3D modelling, 3D printing and development of microfluidic devices, both PDMS based and paper based devices for analytical detection. My aim is to develop affordable, compact and highly sensitive point of care (POC) detection platforms for biomolecule sensing. So, my work involves synthesis/engineering of nanoparticles specific to a particular biomolecule, development of optical sensor followed by the design and fabrication of the POC platform. Supervisors: Soumitra Satapathi Phone: +919745792399 Address: Dept. of Physics, IIT Roorkee, Roorkee, Haridwar, 247667
Development of rapid analytical systems utilizing 3D printing is an emerging area of interest wit... more Development of rapid analytical systems utilizing 3D printing is an emerging area of interest with the potential to provide efficient solutions by integrating multidisciplinary technology without compromising the quality of the system. In this study we report the fabrication of a 3D printing assisted microfluidic based absorbance measurement system, leveraging 3D printing along with integrating miniature optical components for the accurate measurement of biological assays. The developed system is rapid, affordable, and compact, through set of computer-aided design models and fusion deposition modeling 3D printing along with relevant electronic circuitry involving optical components like surface mounting devices. The handheld device features a capacitive touchscreen display, programmed to seamlessly perform MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The device was employed for assessing the cell viability using Michigan cancer foundation-7 (MCF-7) cell lines over varying concentrations of tamoxifen, reciprocating the MTT assay analysis conducted by using spectrophotometer. The device achieved excellent results which upon comparison with the conventional spectrophotometer-based results have shown a correlation coefficient of 0.98. This compact and rapid absorbance measurement system holds significant potential for evaluating the cytotoxicity of drugs, and further development of innovative analytical devices.
In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQD... more In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQDs) and its applicability as a label-free fluorescence sensing probe for the highly sensitive and selective detection of dopamine (DA). Upon addition of DA, the fluorescence intensity of BS-GQDs were effectively quenched over a wide concentration range of DA (0–340 μM) with an ultra-low detection limit of 3.6 μM. The quenching mechanism involved photoinduced electron transfer process from BS-GQDs to dopamine-quinone, produced by the oxidization of DA under alkaline conditions. The proposed sensing mechanism was probed using a detailed study of UV–Vis absorbance, steady state and time resolved fluorescence spectroscopy. The high selectivity of the fluorescent sensor towards DA is established. Our study opens up the possibility of designing a low-cost biosensor which will be suitable for detecting DA in real samples.
In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQD... more In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQDs) and its applicability as a label-free fluorescence sensing probe for the highly sensitive and selective detection of dopamine (DA). Upon addition of DA, the fluorescence intensity of BS-GQDs were effectively quenched over a wide concentration range of DA (0-340 μM) with an ultra-low detection limit of 3.6 μM. The quenching mechanism involved photoinduced electron transfer process from BS-GQDs to dopamine-quinone, produced by the oxidization of DA under alkaline conditions. The proposed sensing mechanism was probed using a detailed study of UV-Vis absorbance, steady state and time resolved fluorescence spectroscopy. The high selectivity of the fluorescent sensor towards DA is established. Our study opens up the possibility of designing a low-cost biosensor which will be suitable for detecting DA in real samples.
Electrospinning is an efficient technique to fabricate nanofibers of controlled diameter and unif... more Electrospinning is an efficient technique to fabricate nanofibers of controlled diameter and uniform morphology. Herein, we report a low-cost and high-yield route to fabricate PAN/DAC composite nanofibers and its use for vapor sensing of 2,4-Dinitrotoluene (DNT) and 2,4,6-Trinitrotoluene (TNT) with a detection level in the range of parts-per-billion. Furthermore, the sensing ability and photo-induced electron transfer mechanism of DAC towards DNT and TNT in the solution phase were also investigated in detail via absorption, steady-state, and time-resolved fluorescence spectroscopy and further supported by density function theory (DFT). The calculated Stern-Volmer quenching constants, 810 M−1 (DNT) and 1170 M−1 (TNT), revealed that DAC is not much sensitive in solution-phase because of the self-condensation phenomenon of DAC molecules. This concern was addressed by the development of a fluorescent nanofiber probe constituting π-electron-rich carbazole (CZ) derivatives, namely 3,6-Diaminocarbazole (DAC) as a fluorescent material and polyacrylonitrile (PAN) as a support polymatrix. This fluorophore-doped nanofiber matrix was fabricated at a relatively lower wt% ratio (PAN:DAC::10:6), obtaining an average diameter of 857 nm and exhibited promising features in the vapor detection of DNT and TNT such as fast response time, excellent sensitivity and selectivity. Reduction of self-condensation caused DAC molecules' fluorescence self-quenching by simply employing the electrospinning technique to cast PAN/DAC nanofibrous film. This work promises a new aspect of sensitivity enhancement of carbazole molecular unit by amine modification and further incorporation into the polymer matrix. This nanofiber-based sensor can lead to the design and development of highly efficient and field-deployable vapor sensors for the detection of nitroaromatic compounds, with application in both explosive sensing and environment pollution.
In today's world, extensive use of various organic explosives such as nitroaromatics, nitrami... more In today's world, extensive use of various organic explosives such as nitroaromatics, nitramines and peroxide can be seen in both military and terrorism. Among the different explosives, 2,4,6-Trinitrotoluene (TNT) and its degraded compound 2,4-Dinitrotoluene (DNT) are the most used energetic material in different legitimately produced explosives and improvised explosive devices (IEDs). The detonation of explosives usually causes damages to the environment, which in turn affects humans’ health and safety. Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. [1,2] In recent years, a number of fluorescent chemosensors/probes have been developed and widely used in chemical sensing of DNT and TNT, especially quantum dots (QDs) and nanoparticles, because of their comprehensive investigation in various applications such as optical sensor, bio-imaging, bio-labeling, biomolecular and NAEs detection. [3] Here, our research efforts are to promote fluorescent Cysteamine capped-CdSe QDs for decorating porous graphene xerogel (GSXS) to design a robust sensor with a new and elegant methodology. Consequently, this sensor can provide good opportunities for visual TNT detection in wearable applications. Graphene oxide (GO), a single monolayer of graphite, has recently attached great scientific attention; besides, the 3D-porous structure of GO has shown impulsive properties, such as large surface areas, high compressibility, ultralow density and adsorption potential. On the other hand, chitosan (CS), alkaline deacetylation of chitin, owned many fascinating properties such as biocompatibility, biodegradability and antimicrobial ability. The 3D-network of GO and CS blend scaffold is expected to have high porosity, surface area, electrochemical properties and high adsorption potential because of hydrogen-bond linking of epoxy groups of GO with the amino group of CS. This nanocomposite could effectively adsorb the QDs and NPs via covalent and non-covalent interactions. Inspired by this top-notch property of GO-CS nanocomposite and the excellent fluorescence property of CdSe QDs, a simple and elegant approach is introduced to design a colorimetric sensor based on QDs decorated graphene xerogel (QD-GSXS), also called GO-CS nanocomposite. Its dual benefit can provide a novel path of sensitive and selective sensing for chemical and biological applications. The preparation of this fluorescent QD-GSXS nanosensor would be a challenge of relevance because of the fluorescent material is usually quenched by graphene. [4] So, this work aims to successfully synthesis fluorescent QD-GSXS nanosensor and exhibits its application for on-site and visual detection of TNT via the formation of the Meisenheimer complex. Herein firstly, we synthesized porous graphene xerogels wrapped with an optimized mass ratio of chitosan. This xerogel surface is further decorated with highly fluorescent Cysteamine capped-CdSe QDs. These composite were characterized using XRD, FE-SEM, FTIR, Raman, BET, UV-Vis and fluorescence spectroscopy. This spongy fluorescent QD-GSXS nanosensor probe was employed for the sensitive and selective detection of TNT. The sensing mechanism is further stabilized via Time-correlated Single Photon Counting (TCSPC) measurement and with the frontier-molecular energy level analysis, calculated by Density-Functional-Theory (DFT). More importantly, we further demonstrated the utility of this designed nanosensor probe as on-site visual TNT sensor by observing a rapid fluorescence change in optical images captured under the illumination of Green Fluorescent Protein (GFP). The design chemosensor showed several advantages, including good selectivity, excellent stability and having linearity with the concentration of TNT. Such a simple colorimetric sensor allows the visual detection of TNT at µM level without any sophisticated instrument. In addition, CdSe-NH2 QDs were also exhibited sensing with DNT and TNT in solution with LOD 18.2 and 9.7 µM, respectively. Considering their structure versatility and design flexibility, we anticipate that our efforts were to combine the electron-donor unit, cystamine capped-CdSe QDs, with an intrinsic porosity of GSXS and make it functional for NAEs detection. This novel and elegant approach gives a new direction to make a prototype chemosensor for visual detection of different NAEs with the advantages of simplicity, ease of operation and high sensitivity. However, there is a wide scope to increase the sensitivity further. This approach will also benefit future research on developing fluorescent hybrid nanosensors based on fluorescent nanoparticles and quantum dots for various chemical and biological applications. References: [1] V. Kumar, B. Maiti, M.K. Chini, P. De, S. Satapathi, Multimodal Fluorescent polymer sensor for Highly sensitive Detection…
Owing to the importance of explosive detection for the security of land and the environment, the ... more Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. In this work, we firstly reported a colorimetric sensor for visual detection of 2,4,6-trinitrotoluene (TNT) based on Cysteamine capped-CdSe quantum dots (QDs) decorated graphene-chitosan xerogel (GSXS), which is shown to have high signal-to-background ratio. Meisenheimer complex formation, which is a well-known sensing mechanism, is characterized by steady state and time resolved spectroscopy supported by Density-Functional-Theory (DFT). Upon Green Fluorescent Protein (GFP) illumination, this stable Meisenheimer complex actively suppresses the attributed fluorescence of QD-GSXS and thus providing a novel path for chemical sensing applications. Under optimized conditions, the sensor displayed a wide linear range from 0.0 to 311.4 μ M with a limit of detection 9.7 μ M. T...
Background The outbreak of the novel coronavirus disease COVID 19, caused by the SARS-CoV-2 virus... more Background The outbreak of the novel coronavirus disease COVID 19, caused by the SARS-CoV-2 virus has spread rapidly around the globe during the past 3 months. As the virus infected cases and mortality rate of this disease is increasing exponentially, scientists and researchers all over the world are relentlessly working to understand this new virus along with possible treatment regimens by discovering active therapeutic agents and vaccines. So, there is an urgent requirement of new and effective medications that can treat the disease caused by SARS CoV 2. Methods and findings We perform the study of drugs that are already available in the market and being used for other diseases to accelerate clinical recovery, in other words repurposing of existing drugs. The vast complexity in drug design and protocols regarding clinical trials often prohibit developing various new drug combinations for this epidemic disease in a limited time. Recently, remarkable improvements in computational po...
Background The outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus... more Background The outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus has spread rapidly around the globe during the past 3 months. As the virus infected cases and mortality rate of this disease is increasing exponentially, scientists and researchers all over the world are relentlessly working to understand this new virus along with possible treatment regimens by discovering active therapeutic agents and vaccines. So, there is an urgent requirement of new and effective medications that can treat the disease caused by SARS-CoV-2. Methods and findings We perform the study of drugs that are already available in the market and being used for other diseases to accelerate clinical recovery, in other words repurposing of existing drugs. The vast complexity in drug design and protocols regarding clinical trials often prohibit developing various new drug combinations for this epidemic disease in a limited time. Recently, remarkable improvements in computational po...
Development of rapid analytical systems utilizing 3D printing is an emerging area of interest wit... more Development of rapid analytical systems utilizing 3D printing is an emerging area of interest with the potential to provide efficient solutions by integrating multidisciplinary technology without compromising the quality of the system. In this study we report the fabrication of a 3D printing assisted microfluidic based absorbance measurement system, leveraging 3D printing along with integrating miniature optical components for the accurate measurement of biological assays. The developed system is rapid, affordable, and compact, through set of computer-aided design models and fusion deposition modeling 3D printing along with relevant electronic circuitry involving optical components like surface mounting devices. The handheld device features a capacitive touchscreen display, programmed to seamlessly perform MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The device was employed for assessing the cell viability using Michigan cancer foundation-7 (MCF-7) cell lines over varying concentrations of tamoxifen, reciprocating the MTT assay analysis conducted by using spectrophotometer. The device achieved excellent results which upon comparison with the conventional spectrophotometer-based results have shown a correlation coefficient of 0.98. This compact and rapid absorbance measurement system holds significant potential for evaluating the cytotoxicity of drugs, and further development of innovative analytical devices.
In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQD... more In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQDs) and its applicability as a label-free fluorescence sensing probe for the highly sensitive and selective detection of dopamine (DA). Upon addition of DA, the fluorescence intensity of BS-GQDs were effectively quenched over a wide concentration range of DA (0–340 μM) with an ultra-low detection limit of 3.6 μM. The quenching mechanism involved photoinduced electron transfer process from BS-GQDs to dopamine-quinone, produced by the oxidization of DA under alkaline conditions. The proposed sensing mechanism was probed using a detailed study of UV–Vis absorbance, steady state and time resolved fluorescence spectroscopy. The high selectivity of the fluorescent sensor towards DA is established. Our study opens up the possibility of designing a low-cost biosensor which will be suitable for detecting DA in real samples.
In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQD... more In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQDs) and its applicability as a label-free fluorescence sensing probe for the highly sensitive and selective detection of dopamine (DA). Upon addition of DA, the fluorescence intensity of BS-GQDs were effectively quenched over a wide concentration range of DA (0-340 μM) with an ultra-low detection limit of 3.6 μM. The quenching mechanism involved photoinduced electron transfer process from BS-GQDs to dopamine-quinone, produced by the oxidization of DA under alkaline conditions. The proposed sensing mechanism was probed using a detailed study of UV-Vis absorbance, steady state and time resolved fluorescence spectroscopy. The high selectivity of the fluorescent sensor towards DA is established. Our study opens up the possibility of designing a low-cost biosensor which will be suitable for detecting DA in real samples.
Electrospinning is an efficient technique to fabricate nanofibers of controlled diameter and unif... more Electrospinning is an efficient technique to fabricate nanofibers of controlled diameter and uniform morphology. Herein, we report a low-cost and high-yield route to fabricate PAN/DAC composite nanofibers and its use for vapor sensing of 2,4-Dinitrotoluene (DNT) and 2,4,6-Trinitrotoluene (TNT) with a detection level in the range of parts-per-billion. Furthermore, the sensing ability and photo-induced electron transfer mechanism of DAC towards DNT and TNT in the solution phase were also investigated in detail via absorption, steady-state, and time-resolved fluorescence spectroscopy and further supported by density function theory (DFT). The calculated Stern-Volmer quenching constants, 810 M−1 (DNT) and 1170 M−1 (TNT), revealed that DAC is not much sensitive in solution-phase because of the self-condensation phenomenon of DAC molecules. This concern was addressed by the development of a fluorescent nanofiber probe constituting π-electron-rich carbazole (CZ) derivatives, namely 3,6-Diaminocarbazole (DAC) as a fluorescent material and polyacrylonitrile (PAN) as a support polymatrix. This fluorophore-doped nanofiber matrix was fabricated at a relatively lower wt% ratio (PAN:DAC::10:6), obtaining an average diameter of 857 nm and exhibited promising features in the vapor detection of DNT and TNT such as fast response time, excellent sensitivity and selectivity. Reduction of self-condensation caused DAC molecules' fluorescence self-quenching by simply employing the electrospinning technique to cast PAN/DAC nanofibrous film. This work promises a new aspect of sensitivity enhancement of carbazole molecular unit by amine modification and further incorporation into the polymer matrix. This nanofiber-based sensor can lead to the design and development of highly efficient and field-deployable vapor sensors for the detection of nitroaromatic compounds, with application in both explosive sensing and environment pollution.
In today's world, extensive use of various organic explosives such as nitroaromatics, nitrami... more In today's world, extensive use of various organic explosives such as nitroaromatics, nitramines and peroxide can be seen in both military and terrorism. Among the different explosives, 2,4,6-Trinitrotoluene (TNT) and its degraded compound 2,4-Dinitrotoluene (DNT) are the most used energetic material in different legitimately produced explosives and improvised explosive devices (IEDs). The detonation of explosives usually causes damages to the environment, which in turn affects humans’ health and safety. Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. [1,2] In recent years, a number of fluorescent chemosensors/probes have been developed and widely used in chemical sensing of DNT and TNT, especially quantum dots (QDs) and nanoparticles, because of their comprehensive investigation in various applications such as optical sensor, bio-imaging, bio-labeling, biomolecular and NAEs detection. [3] Here, our research efforts are to promote fluorescent Cysteamine capped-CdSe QDs for decorating porous graphene xerogel (GSXS) to design a robust sensor with a new and elegant methodology. Consequently, this sensor can provide good opportunities for visual TNT detection in wearable applications. Graphene oxide (GO), a single monolayer of graphite, has recently attached great scientific attention; besides, the 3D-porous structure of GO has shown impulsive properties, such as large surface areas, high compressibility, ultralow density and adsorption potential. On the other hand, chitosan (CS), alkaline deacetylation of chitin, owned many fascinating properties such as biocompatibility, biodegradability and antimicrobial ability. The 3D-network of GO and CS blend scaffold is expected to have high porosity, surface area, electrochemical properties and high adsorption potential because of hydrogen-bond linking of epoxy groups of GO with the amino group of CS. This nanocomposite could effectively adsorb the QDs and NPs via covalent and non-covalent interactions. Inspired by this top-notch property of GO-CS nanocomposite and the excellent fluorescence property of CdSe QDs, a simple and elegant approach is introduced to design a colorimetric sensor based on QDs decorated graphene xerogel (QD-GSXS), also called GO-CS nanocomposite. Its dual benefit can provide a novel path of sensitive and selective sensing for chemical and biological applications. The preparation of this fluorescent QD-GSXS nanosensor would be a challenge of relevance because of the fluorescent material is usually quenched by graphene. [4] So, this work aims to successfully synthesis fluorescent QD-GSXS nanosensor and exhibits its application for on-site and visual detection of TNT via the formation of the Meisenheimer complex. Herein firstly, we synthesized porous graphene xerogels wrapped with an optimized mass ratio of chitosan. This xerogel surface is further decorated with highly fluorescent Cysteamine capped-CdSe QDs. These composite were characterized using XRD, FE-SEM, FTIR, Raman, BET, UV-Vis and fluorescence spectroscopy. This spongy fluorescent QD-GSXS nanosensor probe was employed for the sensitive and selective detection of TNT. The sensing mechanism is further stabilized via Time-correlated Single Photon Counting (TCSPC) measurement and with the frontier-molecular energy level analysis, calculated by Density-Functional-Theory (DFT). More importantly, we further demonstrated the utility of this designed nanosensor probe as on-site visual TNT sensor by observing a rapid fluorescence change in optical images captured under the illumination of Green Fluorescent Protein (GFP). The design chemosensor showed several advantages, including good selectivity, excellent stability and having linearity with the concentration of TNT. Such a simple colorimetric sensor allows the visual detection of TNT at µM level without any sophisticated instrument. In addition, CdSe-NH2 QDs were also exhibited sensing with DNT and TNT in solution with LOD 18.2 and 9.7 µM, respectively. Considering their structure versatility and design flexibility, we anticipate that our efforts were to combine the electron-donor unit, cystamine capped-CdSe QDs, with an intrinsic porosity of GSXS and make it functional for NAEs detection. This novel and elegant approach gives a new direction to make a prototype chemosensor for visual detection of different NAEs with the advantages of simplicity, ease of operation and high sensitivity. However, there is a wide scope to increase the sensitivity further. This approach will also benefit future research on developing fluorescent hybrid nanosensors based on fluorescent nanoparticles and quantum dots for various chemical and biological applications. References: [1] V. Kumar, B. Maiti, M.K. Chini, P. De, S. Satapathi, Multimodal Fluorescent polymer sensor for Highly sensitive Detection…
Owing to the importance of explosive detection for the security of land and the environment, the ... more Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. In this work, we firstly reported a colorimetric sensor for visual detection of 2,4,6-trinitrotoluene (TNT) based on Cysteamine capped-CdSe quantum dots (QDs) decorated graphene-chitosan xerogel (GSXS), which is shown to have high signal-to-background ratio. Meisenheimer complex formation, which is a well-known sensing mechanism, is characterized by steady state and time resolved spectroscopy supported by Density-Functional-Theory (DFT). Upon Green Fluorescent Protein (GFP) illumination, this stable Meisenheimer complex actively suppresses the attributed fluorescence of QD-GSXS and thus providing a novel path for chemical sensing applications. Under optimized conditions, the sensor displayed a wide linear range from 0.0 to 311.4 μ M with a limit of detection 9.7 μ M. T...
Background The outbreak of the novel coronavirus disease COVID 19, caused by the SARS-CoV-2 virus... more Background The outbreak of the novel coronavirus disease COVID 19, caused by the SARS-CoV-2 virus has spread rapidly around the globe during the past 3 months. As the virus infected cases and mortality rate of this disease is increasing exponentially, scientists and researchers all over the world are relentlessly working to understand this new virus along with possible treatment regimens by discovering active therapeutic agents and vaccines. So, there is an urgent requirement of new and effective medications that can treat the disease caused by SARS CoV 2. Methods and findings We perform the study of drugs that are already available in the market and being used for other diseases to accelerate clinical recovery, in other words repurposing of existing drugs. The vast complexity in drug design and protocols regarding clinical trials often prohibit developing various new drug combinations for this epidemic disease in a limited time. Recently, remarkable improvements in computational po...
Background The outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus... more Background The outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus has spread rapidly around the globe during the past 3 months. As the virus infected cases and mortality rate of this disease is increasing exponentially, scientists and researchers all over the world are relentlessly working to understand this new virus along with possible treatment regimens by discovering active therapeutic agents and vaccines. So, there is an urgent requirement of new and effective medications that can treat the disease caused by SARS-CoV-2. Methods and findings We perform the study of drugs that are already available in the market and being used for other diseases to accelerate clinical recovery, in other words repurposing of existing drugs. The vast complexity in drug design and protocols regarding clinical trials often prohibit developing various new drug combinations for this epidemic disease in a limited time. Recently, remarkable improvements in computational po...
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