Amit kunwar - Academia.edu (original) (raw)

Papers by Amit kunwar

Journal of Spices and Aromatic Crops

The objective of this study was to characterise the putative phytochemical constituents from petr... more The objective of this study was to characterise the putative phytochemical constituents from petroleum ether (CC-P) and chloroform (CC-C) extracts of Curcuma. caesia rhizome by GC-MS analysis and to compare their bioactivities. GC-MS analysis facilitated the documentation of a total of 16 and 20 volatile constituents in CC-P and CC-C extracts respectively. Of these the major constituents present in CC-P were cycloisolongifolence, 8, 9-dehydro-9 formyl- (19.64%), 4-oxo- β-isodamascol (16.05%), 6,10-dimethyl-3- (1-methylethyl) -6-cyclodecene-1,4-dione (13.80%), 2H-cyclohepta[b]furan-2-one,6-[1-(acetyloxy) -3-oxobutyl]- 3,3a,4,7,8,8a- hexahydro-7-methyl- 3-methylene- (9.08%), tricycle [5.1.0.0(2,4)] oct-5-ene-5-propanoic acid,3,3,8.8-tetramethyl- (6.39%), 2(3H)-benzofuranone,6-ethenylhexahydro-3,6-dimethyl-7-(1- methyl ethenyl)-, [3S-(3α,3aα,6α,7β,7aβ) (4.18%) and 7a-isopropenyl-4,5-dimethy loctahydroindene-4-carboxylic acid (4.01%). Similarly, the major constituents present in CC-C we...

International Journal of Pharmaceutical Investigation

New Journal of Chemistry

Among the 22 organoselenium compounds studied, 2-Py2Se2 & Nict2Se2 showed the highest affinity fo... more Among the 22 organoselenium compounds studied, 2-Py2Se2 & Nict2Se2 showed the highest affinity for Mpro. The biochemical studies confirmed their superiority as compared to standard compound like Ebselen in terms of the IC50 required for Mpro inhibition.

The 1st International Electronic Conference on Catalysis Sciences, 2020

Over the years, organodiselenides have emerged as the biologically relevant class of molecules. O... more Over the years, organodiselenides have emerged as the biologically relevant class of molecules. On the one hand, such compounds are known for pro-oxidant effects leading to toxicity in biological systems. On the other hand, there are growing evidences about their bio-mimetic activities as catalysts such as glutathione peroxidase (GPx)-like activity. Our recent work has explored this paradoxical behavior of diselenides in developing antioxidants and/or anticancer agents. For this purpose, a number of alkyl and aryl diselenides have been evaluated in different biological models. The results have shown that aryl diselenides, in particular pyridinediselenides, altered the ratio of the intracellular thiol redox pairs of glutathione (GSH) and glutathione disulfide (GSSG) towards reduction (antioxidant) rather than oxidation (pro-oxidant) to protect normal cells against radiation damage and to induce cytotoxicity in tumor cells. Further, these studies have also postulated that the intracellular redox state, the level of thioredoxin reductase (TrxR), and reductive intermediates (e.g., selenol and/or selone) might play a very important role in the manifestation of the toxicities of aryl diselenides in cells.

Materials Advances, 2021

Deep eutectic solvents as versatile green media for the synthesis of non-toxic photoluminescent t... more Deep eutectic solvents as versatile green media for the synthesis of non-toxic photoluminescent tin oxide nanoparticles with potential applications demonstrated in cell imaging and as antioxidants.

Structure -property correlation in 2, 2′-dipyridyl diselenide derivatives has been investigated u... more Structure -property correlation in 2, 2′-dipyridyl diselenide derivatives has been investigated using four test cases 2, 2′-dipyridyl diselenide ( 1 ), 2, 2′-disleno bis(3-pyridinol) ( 2 ), 2, 2′-diseleno bis(3-carboxypyridine) ( 3 ) and 2, 2′-diselenobis ( 3-nicotinamide) ( 4 ). N ature of substituent at C-3 position of pyridyl ring has been found to be a key factor in controlling the molecular structure, its packing capacity and thermal stability of molecular assembly. Strong electron withdrawing group ( viz. -COOH, -CONH 2 ) reduces the charge on selenium and enforces sp 2 hybridization induced planar molecular configuration. Bent molecules 1 and 2 favors denser crystallographic packing in comparison to planar molecule 3 and 4 . Thermal investigation reveal that temperature range for thermal decomposition to elemental selenium for 4 and 2 is 210-460°C and 150-275°C respectively indicating higher thermal stability of former. The higher thermal stability of 4 has been attributed to...

Free Radical Research, 2021

Abstract Antioxidant activity of organoselenium compounds belonging to different classes i.e. fun... more Abstract Antioxidant activity of organoselenium compounds belonging to different classes i.e. functionalized aliphatic, aromatic and cyclic selenoethers, are compared on the basis of their ability to scavenge reactive oxygen species like hydroxyl and peroxyl radicals and to exhibit glutathione peroxidase (GPx) like catalytic activity. The comparative analysis has revealed that the antioxidant activity of the organoselenium compounds show direct correlation with the energy of the highest occupied molecular orbital (HOMO) and neighboring group participation that stabilizes the reaction intermediate. Finally, structural features responsible for improving the rate of reaction of organoselenium compounds with free radical/molecular oxidants have been discussed on the basis of the compounds screened at our institute.

Journal of Molecular Liquids, 2021

Abstract The inherent advantages of Silicon have made it as one of the most sought-after elements... more Abstract The inherent advantages of Silicon have made it as one of the most sought-after elements in the field of nanoscience and nanotechnology. Herein, we report an electron-beam induced formation of blue light emitting organosilicon nanoparticles (OSiNPs) in the micellar medium of Triton X-100 (TX-100). The profound role of the micellar medium can be realized from the enhanced colloidal stability as well as photoluminescence (PL) quantum efficiency (from ~9% to ~55%) of as synthesized OSiNPs. Mechanistic investigations revealed the crucial role of hydroxyl radical ( OH) in the formation of OSiNPs. XPS and FTIR studies indicated the presence of siloxane/silicone and silica (SiO2) like units as the major constituents in the NPs. XRD pattern showed the amorphous nature of the NPs, while TEM studies revealed their aggregation. The hydrodynamic size of the NPs was determined to be ~24 nm. Interestingly, the NPs exhibited an excitation-wavelength-dependent PL behaviour, thereby indicating the presence of multiple emission centres (ECs). Detailed investigations based on steady-state as well as time-resolved PL measurements were conducted to analyse these ECs. In addition, pH and temperature-dependent studies were carried out to further substantiate these findings. Moreover, the experimental observations revealed their potential applications in the areas of thermosensing, fingerprinting and cell-imaging. Notably, the internalization of as prepared NPs within cells was evident from the bright fluorescence images obtained from the cytoplasmic region as compared to control cells. This observation also suggests the prospective application of these NPs for image guided drug delivery systems.

Journal of Molecular Liquids, 2021

Abstract Importance of pluronic P85 as carrier for drugs arises due to its ability to sensitize c... more Abstract Importance of pluronic P85 as carrier for drugs arises due to its ability to sensitize cell membranes for delivery of drugs across multi drug resistant cancer cells and blood brain barrier. It is thus necessary to understand how lipophilic drugs and phytochemicals influence its self-assembly characteristics and how the therapeutic properties of these lipophiles are modulated upon encapsulation in P85 micelles. We have investigated solubilization characteristics of Lavender essential oil (LO) in P85 and P85-P123 micellar systems and studied the associated structural and therapeutic properties by DLS, SANS, viscosity, ITC, antimicrobial and in vitro cancer cell viability studies. We observed that LO induces micellar structural transitions in aqueous P85 and P85-P123 systems leading to the formations of worm like micelles and vesicles. LO solubilized systems exhibit anticancer and antimicrobial properties, and show existence of double cloud points namely, upper and lower cloud points (UCP & LCP). A spherical-to-elliptical micellar structural transition is observed in these LO solubilized systems upon cooling down to LCP, which is unusual and not reported hitherto in aqueous pluronic systems. The observed results show how essential oils can influence the self-assembly characteristics of P85 based micellar systems and how their therapeutic properties are manifested under micellar encapsulation.

Herein, we report an electron beam mediated one-pot, rapid approach for the synthesis of blue lig... more Herein, we report an electron beam mediated one-pot, rapid approach for the synthesis of blue light emitting organosilicon oxide nanoparticles (OSiNPs) in aqueous solution with a potential for scale-up production. Mechanistic studies based on pulse radiolysis revealed that unlike the generally believed solvated electron (e sol ─) driven process, the present synthesis proceeds through the reaction of hydroxyl radical (•OH) with the precursor molecules resulting in the formation of silane-derived radicals. Subsequently, these radicals react with each other to form OSiNPs. Compositional studies by XPS, FTIR and Raman indicate the presence of siloxane/silicone and silica (SiO2) like units as the major constituents in the NPs. XRD pattern signifies the amorphous nature of the NPs, while imaging studies revealed self-assembling of NPs (3-5 nm) into a porous structure. Notably, the NPs exhibited excitation wavelength dependent photoluminescence (PL) spectra, pointing to the presence of multiple emission centres with varying energy levels. The nature of these emission centres and their heterogeneous distribution was analysed in detail through pH and absorbed dose dependent PL studies, HF treatment, fluorescence excitation spectrum, temperature dependent steady state and time resolved PL studies. Moreover, OSiNPs were functionalized with a biocompatible ligand, i.e. L-Glutathione (L-Glu), which significantly enhanced the quantum efficiency (up to ~25%) of emission as well as colloidal stability. These functionalized NPs (L-Glu@OSiNPs) were found to exhibit vary less toxicity up to a concentration of ~ 0.5 g/ml. Interestingly, the L-Glu@OSiNPs exhibited tumor selectivity (in A549 human lung cancer cells) at lower pH along with cell labelling capabilities with propensity to localize at the nucleus. Furthermore, in addition to their usage in anti-counterfeiting measures, application of L-Glu@OSiNPs in fingerprinting was also demonstrated by testing on variety of surfaces. Meanwhile, linear and reproducible PL intensity variations of OSiNPs signify highly sensitive and robust thermosensing properties of OSiNPs.

Radiotherapy and Oncology, 2018

Journal of Organometallic Chemistry, 2017

Abstract 2,2′-Diselenobis(3-pyridinol), [2-C5H3N(3-OH)Se]2 (DISPOL) (1) and 3-hydroxypyridine-2-(... more Abstract 2,2′-Diselenobis(3-pyridinol), [2-C5H3N(3-OH)Se]2 (DISPOL) (1) and 3-hydroxypyridine-2-(1H) selone (2) were synthesized and characterized by microanalyses, NMR (1H, 13C{1H}, and 77Se{1H}) spectroscopy. The 1 on recrystallization from various organic and aqueous solutions resulted in different polymorphs which were unambiguously characterized by single crystal X-ray diffraction analyses at room as well as low temperatures. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) of 1 confirmed the existence of two polymorphs. The bulk 1 and its polymorphs exhibited potent cytotoxicity against A549 human lung carcinoma cells (IC50 values ≈ 10 μM). The compound is thermodynamically stable and is a promising candidate for further pharmacological studies as a cytotoxic agent.

Current Pharmaceutical Design, 2019

Background: Cancer is the major public health problem in developing countries. The treatment of c... more Background: Cancer is the major public health problem in developing countries. The treatment of cancer requires a multimodal approach and chemotherapy is one of them. Chemotherapeutic drug is administered to cancer patients in the form of a formulation which is prepared by mixing an active ingredient (drug) with the excipient. The role of excipient in a formulation is to regulate the release, bio-distribution, and selectivity of drug within the body. Methods: In this context, selectivity of an anticancer formulation is achieved through two mechanisms like passive and active targeting. The passive targeting of a formulation is generally through enhanced permeation retention (EPR) effect which is dictated by physical properties of the carrier such as shape and size. On the contrary, active targeting means surface functionalization of excipient with target-specific ligands and/or receptors to increase its selectivity. Results: Over the past several decades, remarkable progress has been...

Regulatory toxicology and pharmacology : RTP, Jan 18, 2018

Diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine was e... more Diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine was evaluated for acute toxicity, mutagenic safety and metabolic stability. The estimated median oral lethal dose (LD) cut-off of DSePA in mice and rat models was ∼200 mg/kg and ∼25 mg/kg respectively, which is considerably higher than the reported oral LD dose of its parent compound. Subsequently DSePA treatment in absence and presence of rat liver S9 fraction was found to be non-mutagenic at the tested doses up to 1 mM in rifampicin resistance assay and up to 6 mM in Ames test. In vitro degradation studies indicated that DSePA was more stable in S9 fraction of human compared to rat. The kinetic parameters K and V of DSePA degradation estimated using rat S9 fraction was 9.81 μM and 1.06 nmol/ml/min respectively. Further, DSePA treatment (1-50 μM) with or without rat S9 fraction did not induce any toxicity in human intestinal epithelial cells (Int 407) while showing comparable bioactivity of ...

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 25, 2018

The interaction of the cupric ion with esculetin, a dihydroxy coumarin derivative, was studied by... more The interaction of the cupric ion with esculetin, a dihydroxy coumarin derivative, was studied by absorption and fluorescence spectroscopic methods in aqueous medium. Esculetin formed a complex in the presence of the cupric ion which was characterised by the shift in its absorption band from 350 nm to 389 nm and the quenching of its fluorescence intensity at 466 nm. From Job's plot and fluorescence quenching studies, the stoichiometry of the copper ion and esculetin in the complex was estimated to be 1 : 2 respectively. Interestingly, the incubation of the Cu(ii)-esculetin complex with a thiol peptide, glutathione (GSH), showed restoration of the fluorescence intensity as well as absorption maxima to that of pure esculetin. Incubation with other common thiol and non-sulphur amino acids did not show a similar restoration of the photophysical properties of the complex except in the case of cysteine. Mechanistically, it was evident that two molecules of GSH were consumed in reducin...

Materials Chemistry and Physics, 2017

CdSe quantum dots were synthesized in aqueous solutions using equimolar cadmium sulfate and sodiu... more CdSe quantum dots were synthesized in aqueous solutions using equimolar cadmium sulfate and sodium selenosulfate in aqueous solutions through 7 MeV electron beam irradiation in a linear electron accelerator, LINAC in the presence of different saccharides, such as fructose, glucose, sucrose and starch. The as grown CdSe quantum dots in colloidal solution were fairly stable under ambient conditions and exhibit room temperature excitonic absorption and broad fluorescence. Among the saccharides used in this study, starch was found to have a better capping property, whereas glucose was found to reduce their cytotoxicity effect to a larger extent as compared to other saccharides. The mechanism of radiolytic synthesis of these quantum dots was investigated by pulse radiolysis studies.

Metallomics : integrated biometal science, Jun 1, 2017

Diselenonicotinamide (DSNA), a synthetic organoselenium compound, was evaluated for its radioprot... more Diselenonicotinamide (DSNA), a synthetic organoselenium compound, was evaluated for its radioprotective effect in cellular models. A clonogenic assay in Chinese Hamster Ovary (CHO) cells and an apoptosis assay in murine splenic lymphocytes indicated that pre-treatment with DSNA at a concentration of 25 μM significantly protected them from radiation-induced cell death. Upon irradiation (1-12 Gy), dose-response studies were carried out under similar treatment conditions, and its dose modification factor (DMF) was estimated to be 1.26. Furthermore, DSNA showed its radioprotective effect, even when administered after exposure to radiation. Mechanistic investigation revealed that DSNA increased the intracellular levels of GPx and GSH in irradiated cells. In line with this observation, the addition of a pharmacological inhibitor of GPx cycle, abrogated the activity of DSNA. The radioprotective effect of DSNA was also complemented by its ability to prevent radiation-induced DNA damage as m...

Industrial & Engineering Chemistry Research, 2016

Synthesis of intrinsically radiolabeled nanoparticles is an emerging concept in cancer theranosti... more Synthesis of intrinsically radiolabeled nanoparticles is an emerging concept in cancer theranostics and is expected to play an imperative role in translating nanotechnology research into the nuclear medicine industry. In order to reduce reliance on cyclotron produced 64 Cu (t 1/2 = 12.7 h, EC 45%, β + 17.9%, β − 37.1%) and increase global accessibility of this radioisotope for preclinical and clinical investigations, we have explored the feasibility of using neutron-activated 64 Cu produced in research reactors for potential use in cancer theranostics. A viable strategy has been developed for production of 64 Cu in medium-flux research reactors and its utilization toward industrial-scale (GBq level) synthesis of intrinsically radiolabeled 64 CuS nanoparticles (∼30 nm particle size). The synthesis procedure was easily executable in a hot cell equipped with remotely operable gadgets and 64 CuS nanoparticles could be synthesized in a form suitable for clinical administration. The stability of the nanoparticles under physiological conditions was established by detailed in vitro studies in phosphate buffered saline (PBS) and mouse serum media. The biological efficacy of intrinsically radiolabeled 64 CuS nanoparticles was studied in C57BL/6 mice bearing melanoma tumors. The results of the biodistribution studies revealed significant tumor uptake (4.64% ± 1.71%ID/g) within 4 h post-injection (where %ID is the percent injected radioactivity dose), with good tumor-to-background contrast. Collectively, the promising results obtained in this study suggest that the concept of intrinsically radiolabeled nanoplatforms can be employed to facilitate widespread utilization of neutron-activated 64 Cu in nuclear medicine industry.

Bulletin of the Chemical Society of Japan, 2016

has received her Ph.D. degree in chemistry from University of Mumbai. She had joined Bhabha Atomi... more has received her Ph.D. degree in chemistry from University of Mumbai. She had joined Bhabha Atomic Research Centre, India as a K. S. Krishnan Research Associate and later promoted as a scientist in Radiation and Photochemistry Division in the same institute. Her research work is involved in developing organoselenium compounds as new class of antioxidants, which shows both free radical scavenging and glutathione peroxidase enzyme mimicking activity that enables higher antioxidant/ radioprotection activity even at low concentration. K. Indira Priyadarsini Dr. K. Indira Priyadarsini, an outstanding scientist at Bhabha Atomic Research Centre, is working in the multidisciplinary research areas of chemistry and biology on development of antioxidants and radioprotectors. Her research interests are on free radical reaction dynamics, radiation chemistry and enzyme kinetics, development of antioxidants and radioprotectors from natural products and organoselenium compounds.

Journal of Spices and Aromatic Crops

The objective of this study was to characterise the putative phytochemical constituents from petr... more The objective of this study was to characterise the putative phytochemical constituents from petroleum ether (CC-P) and chloroform (CC-C) extracts of Curcuma. caesia rhizome by GC-MS analysis and to compare their bioactivities. GC-MS analysis facilitated the documentation of a total of 16 and 20 volatile constituents in CC-P and CC-C extracts respectively. Of these the major constituents present in CC-P were cycloisolongifolence, 8, 9-dehydro-9 formyl- (19.64%), 4-oxo- β-isodamascol (16.05%), 6,10-dimethyl-3- (1-methylethyl) -6-cyclodecene-1,4-dione (13.80%), 2H-cyclohepta[b]furan-2-one,6-[1-(acetyloxy) -3-oxobutyl]- 3,3a,4,7,8,8a- hexahydro-7-methyl- 3-methylene- (9.08%), tricycle [5.1.0.0(2,4)] oct-5-ene-5-propanoic acid,3,3,8.8-tetramethyl- (6.39%), 2(3H)-benzofuranone,6-ethenylhexahydro-3,6-dimethyl-7-(1- methyl ethenyl)-, [3S-(3α,3aα,6α,7β,7aβ) (4.18%) and 7a-isopropenyl-4,5-dimethy loctahydroindene-4-carboxylic acid (4.01%). Similarly, the major constituents present in CC-C we...

International Journal of Pharmaceutical Investigation

New Journal of Chemistry

Among the 22 organoselenium compounds studied, 2-Py2Se2 & Nict2Se2 showed the highest affinity fo... more Among the 22 organoselenium compounds studied, 2-Py2Se2 & Nict2Se2 showed the highest affinity for Mpro. The biochemical studies confirmed their superiority as compared to standard compound like Ebselen in terms of the IC50 required for Mpro inhibition.

The 1st International Electronic Conference on Catalysis Sciences, 2020

Over the years, organodiselenides have emerged as the biologically relevant class of molecules. O... more Over the years, organodiselenides have emerged as the biologically relevant class of molecules. On the one hand, such compounds are known for pro-oxidant effects leading to toxicity in biological systems. On the other hand, there are growing evidences about their bio-mimetic activities as catalysts such as glutathione peroxidase (GPx)-like activity. Our recent work has explored this paradoxical behavior of diselenides in developing antioxidants and/or anticancer agents. For this purpose, a number of alkyl and aryl diselenides have been evaluated in different biological models. The results have shown that aryl diselenides, in particular pyridinediselenides, altered the ratio of the intracellular thiol redox pairs of glutathione (GSH) and glutathione disulfide (GSSG) towards reduction (antioxidant) rather than oxidation (pro-oxidant) to protect normal cells against radiation damage and to induce cytotoxicity in tumor cells. Further, these studies have also postulated that the intracellular redox state, the level of thioredoxin reductase (TrxR), and reductive intermediates (e.g., selenol and/or selone) might play a very important role in the manifestation of the toxicities of aryl diselenides in cells.

Materials Advances, 2021

Deep eutectic solvents as versatile green media for the synthesis of non-toxic photoluminescent t... more Deep eutectic solvents as versatile green media for the synthesis of non-toxic photoluminescent tin oxide nanoparticles with potential applications demonstrated in cell imaging and as antioxidants.

Structure -property correlation in 2, 2′-dipyridyl diselenide derivatives has been investigated u... more Structure -property correlation in 2, 2′-dipyridyl diselenide derivatives has been investigated using four test cases 2, 2′-dipyridyl diselenide ( 1 ), 2, 2′-disleno bis(3-pyridinol) ( 2 ), 2, 2′-diseleno bis(3-carboxypyridine) ( 3 ) and 2, 2′-diselenobis ( 3-nicotinamide) ( 4 ). N ature of substituent at C-3 position of pyridyl ring has been found to be a key factor in controlling the molecular structure, its packing capacity and thermal stability of molecular assembly. Strong electron withdrawing group ( viz. -COOH, -CONH 2 ) reduces the charge on selenium and enforces sp 2 hybridization induced planar molecular configuration. Bent molecules 1 and 2 favors denser crystallographic packing in comparison to planar molecule 3 and 4 . Thermal investigation reveal that temperature range for thermal decomposition to elemental selenium for 4 and 2 is 210-460°C and 150-275°C respectively indicating higher thermal stability of former. The higher thermal stability of 4 has been attributed to...

Free Radical Research, 2021

Abstract Antioxidant activity of organoselenium compounds belonging to different classes i.e. fun... more Abstract Antioxidant activity of organoselenium compounds belonging to different classes i.e. functionalized aliphatic, aromatic and cyclic selenoethers, are compared on the basis of their ability to scavenge reactive oxygen species like hydroxyl and peroxyl radicals and to exhibit glutathione peroxidase (GPx) like catalytic activity. The comparative analysis has revealed that the antioxidant activity of the organoselenium compounds show direct correlation with the energy of the highest occupied molecular orbital (HOMO) and neighboring group participation that stabilizes the reaction intermediate. Finally, structural features responsible for improving the rate of reaction of organoselenium compounds with free radical/molecular oxidants have been discussed on the basis of the compounds screened at our institute.

Journal of Molecular Liquids, 2021

Abstract The inherent advantages of Silicon have made it as one of the most sought-after elements... more Abstract The inherent advantages of Silicon have made it as one of the most sought-after elements in the field of nanoscience and nanotechnology. Herein, we report an electron-beam induced formation of blue light emitting organosilicon nanoparticles (OSiNPs) in the micellar medium of Triton X-100 (TX-100). The profound role of the micellar medium can be realized from the enhanced colloidal stability as well as photoluminescence (PL) quantum efficiency (from ~9% to ~55%) of as synthesized OSiNPs. Mechanistic investigations revealed the crucial role of hydroxyl radical ( OH) in the formation of OSiNPs. XPS and FTIR studies indicated the presence of siloxane/silicone and silica (SiO2) like units as the major constituents in the NPs. XRD pattern showed the amorphous nature of the NPs, while TEM studies revealed their aggregation. The hydrodynamic size of the NPs was determined to be ~24 nm. Interestingly, the NPs exhibited an excitation-wavelength-dependent PL behaviour, thereby indicating the presence of multiple emission centres (ECs). Detailed investigations based on steady-state as well as time-resolved PL measurements were conducted to analyse these ECs. In addition, pH and temperature-dependent studies were carried out to further substantiate these findings. Moreover, the experimental observations revealed their potential applications in the areas of thermosensing, fingerprinting and cell-imaging. Notably, the internalization of as prepared NPs within cells was evident from the bright fluorescence images obtained from the cytoplasmic region as compared to control cells. This observation also suggests the prospective application of these NPs for image guided drug delivery systems.

Journal of Molecular Liquids, 2021

Abstract Importance of pluronic P85 as carrier for drugs arises due to its ability to sensitize c... more Abstract Importance of pluronic P85 as carrier for drugs arises due to its ability to sensitize cell membranes for delivery of drugs across multi drug resistant cancer cells and blood brain barrier. It is thus necessary to understand how lipophilic drugs and phytochemicals influence its self-assembly characteristics and how the therapeutic properties of these lipophiles are modulated upon encapsulation in P85 micelles. We have investigated solubilization characteristics of Lavender essential oil (LO) in P85 and P85-P123 micellar systems and studied the associated structural and therapeutic properties by DLS, SANS, viscosity, ITC, antimicrobial and in vitro cancer cell viability studies. We observed that LO induces micellar structural transitions in aqueous P85 and P85-P123 systems leading to the formations of worm like micelles and vesicles. LO solubilized systems exhibit anticancer and antimicrobial properties, and show existence of double cloud points namely, upper and lower cloud points (UCP & LCP). A spherical-to-elliptical micellar structural transition is observed in these LO solubilized systems upon cooling down to LCP, which is unusual and not reported hitherto in aqueous pluronic systems. The observed results show how essential oils can influence the self-assembly characteristics of P85 based micellar systems and how their therapeutic properties are manifested under micellar encapsulation.

Herein, we report an electron beam mediated one-pot, rapid approach for the synthesis of blue lig... more Herein, we report an electron beam mediated one-pot, rapid approach for the synthesis of blue light emitting organosilicon oxide nanoparticles (OSiNPs) in aqueous solution with a potential for scale-up production. Mechanistic studies based on pulse radiolysis revealed that unlike the generally believed solvated electron (e sol ─) driven process, the present synthesis proceeds through the reaction of hydroxyl radical (•OH) with the precursor molecules resulting in the formation of silane-derived radicals. Subsequently, these radicals react with each other to form OSiNPs. Compositional studies by XPS, FTIR and Raman indicate the presence of siloxane/silicone and silica (SiO2) like units as the major constituents in the NPs. XRD pattern signifies the amorphous nature of the NPs, while imaging studies revealed self-assembling of NPs (3-5 nm) into a porous structure. Notably, the NPs exhibited excitation wavelength dependent photoluminescence (PL) spectra, pointing to the presence of multiple emission centres with varying energy levels. The nature of these emission centres and their heterogeneous distribution was analysed in detail through pH and absorbed dose dependent PL studies, HF treatment, fluorescence excitation spectrum, temperature dependent steady state and time resolved PL studies. Moreover, OSiNPs were functionalized with a biocompatible ligand, i.e. L-Glutathione (L-Glu), which significantly enhanced the quantum efficiency (up to ~25%) of emission as well as colloidal stability. These functionalized NPs (L-Glu@OSiNPs) were found to exhibit vary less toxicity up to a concentration of ~ 0.5 g/ml. Interestingly, the L-Glu@OSiNPs exhibited tumor selectivity (in A549 human lung cancer cells) at lower pH along with cell labelling capabilities with propensity to localize at the nucleus. Furthermore, in addition to their usage in anti-counterfeiting measures, application of L-Glu@OSiNPs in fingerprinting was also demonstrated by testing on variety of surfaces. Meanwhile, linear and reproducible PL intensity variations of OSiNPs signify highly sensitive and robust thermosensing properties of OSiNPs.

Radiotherapy and Oncology, 2018

Journal of Organometallic Chemistry, 2017

Abstract 2,2′-Diselenobis(3-pyridinol), [2-C5H3N(3-OH)Se]2 (DISPOL) (1) and 3-hydroxypyridine-2-(... more Abstract 2,2′-Diselenobis(3-pyridinol), [2-C5H3N(3-OH)Se]2 (DISPOL) (1) and 3-hydroxypyridine-2-(1H) selone (2) were synthesized and characterized by microanalyses, NMR (1H, 13C{1H}, and 77Se{1H}) spectroscopy. The 1 on recrystallization from various organic and aqueous solutions resulted in different polymorphs which were unambiguously characterized by single crystal X-ray diffraction analyses at room as well as low temperatures. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) of 1 confirmed the existence of two polymorphs. The bulk 1 and its polymorphs exhibited potent cytotoxicity against A549 human lung carcinoma cells (IC50 values ≈ 10 μM). The compound is thermodynamically stable and is a promising candidate for further pharmacological studies as a cytotoxic agent.

Current Pharmaceutical Design, 2019

Background: Cancer is the major public health problem in developing countries. The treatment of c... more Background: Cancer is the major public health problem in developing countries. The treatment of cancer requires a multimodal approach and chemotherapy is one of them. Chemotherapeutic drug is administered to cancer patients in the form of a formulation which is prepared by mixing an active ingredient (drug) with the excipient. The role of excipient in a formulation is to regulate the release, bio-distribution, and selectivity of drug within the body. Methods: In this context, selectivity of an anticancer formulation is achieved through two mechanisms like passive and active targeting. The passive targeting of a formulation is generally through enhanced permeation retention (EPR) effect which is dictated by physical properties of the carrier such as shape and size. On the contrary, active targeting means surface functionalization of excipient with target-specific ligands and/or receptors to increase its selectivity. Results: Over the past several decades, remarkable progress has been...

Regulatory toxicology and pharmacology : RTP, Jan 18, 2018

Diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine was e... more Diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine was evaluated for acute toxicity, mutagenic safety and metabolic stability. The estimated median oral lethal dose (LD) cut-off of DSePA in mice and rat models was ∼200 mg/kg and ∼25 mg/kg respectively, which is considerably higher than the reported oral LD dose of its parent compound. Subsequently DSePA treatment in absence and presence of rat liver S9 fraction was found to be non-mutagenic at the tested doses up to 1 mM in rifampicin resistance assay and up to 6 mM in Ames test. In vitro degradation studies indicated that DSePA was more stable in S9 fraction of human compared to rat. The kinetic parameters K and V of DSePA degradation estimated using rat S9 fraction was 9.81 μM and 1.06 nmol/ml/min respectively. Further, DSePA treatment (1-50 μM) with or without rat S9 fraction did not induce any toxicity in human intestinal epithelial cells (Int 407) while showing comparable bioactivity of ...

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 25, 2018

The interaction of the cupric ion with esculetin, a dihydroxy coumarin derivative, was studied by... more The interaction of the cupric ion with esculetin, a dihydroxy coumarin derivative, was studied by absorption and fluorescence spectroscopic methods in aqueous medium. Esculetin formed a complex in the presence of the cupric ion which was characterised by the shift in its absorption band from 350 nm to 389 nm and the quenching of its fluorescence intensity at 466 nm. From Job's plot and fluorescence quenching studies, the stoichiometry of the copper ion and esculetin in the complex was estimated to be 1 : 2 respectively. Interestingly, the incubation of the Cu(ii)-esculetin complex with a thiol peptide, glutathione (GSH), showed restoration of the fluorescence intensity as well as absorption maxima to that of pure esculetin. Incubation with other common thiol and non-sulphur amino acids did not show a similar restoration of the photophysical properties of the complex except in the case of cysteine. Mechanistically, it was evident that two molecules of GSH were consumed in reducin...

Materials Chemistry and Physics, 2017

CdSe quantum dots were synthesized in aqueous solutions using equimolar cadmium sulfate and sodiu... more CdSe quantum dots were synthesized in aqueous solutions using equimolar cadmium sulfate and sodium selenosulfate in aqueous solutions through 7 MeV electron beam irradiation in a linear electron accelerator, LINAC in the presence of different saccharides, such as fructose, glucose, sucrose and starch. The as grown CdSe quantum dots in colloidal solution were fairly stable under ambient conditions and exhibit room temperature excitonic absorption and broad fluorescence. Among the saccharides used in this study, starch was found to have a better capping property, whereas glucose was found to reduce their cytotoxicity effect to a larger extent as compared to other saccharides. The mechanism of radiolytic synthesis of these quantum dots was investigated by pulse radiolysis studies.

Metallomics : integrated biometal science, Jun 1, 2017

Diselenonicotinamide (DSNA), a synthetic organoselenium compound, was evaluated for its radioprot... more Diselenonicotinamide (DSNA), a synthetic organoselenium compound, was evaluated for its radioprotective effect in cellular models. A clonogenic assay in Chinese Hamster Ovary (CHO) cells and an apoptosis assay in murine splenic lymphocytes indicated that pre-treatment with DSNA at a concentration of 25 μM significantly protected them from radiation-induced cell death. Upon irradiation (1-12 Gy), dose-response studies were carried out under similar treatment conditions, and its dose modification factor (DMF) was estimated to be 1.26. Furthermore, DSNA showed its radioprotective effect, even when administered after exposure to radiation. Mechanistic investigation revealed that DSNA increased the intracellular levels of GPx and GSH in irradiated cells. In line with this observation, the addition of a pharmacological inhibitor of GPx cycle, abrogated the activity of DSNA. The radioprotective effect of DSNA was also complemented by its ability to prevent radiation-induced DNA damage as m...

Industrial & Engineering Chemistry Research, 2016

Synthesis of intrinsically radiolabeled nanoparticles is an emerging concept in cancer theranosti... more Synthesis of intrinsically radiolabeled nanoparticles is an emerging concept in cancer theranostics and is expected to play an imperative role in translating nanotechnology research into the nuclear medicine industry. In order to reduce reliance on cyclotron produced 64 Cu (t 1/2 = 12.7 h, EC 45%, β + 17.9%, β − 37.1%) and increase global accessibility of this radioisotope for preclinical and clinical investigations, we have explored the feasibility of using neutron-activated 64 Cu produced in research reactors for potential use in cancer theranostics. A viable strategy has been developed for production of 64 Cu in medium-flux research reactors and its utilization toward industrial-scale (GBq level) synthesis of intrinsically radiolabeled 64 CuS nanoparticles (∼30 nm particle size). The synthesis procedure was easily executable in a hot cell equipped with remotely operable gadgets and 64 CuS nanoparticles could be synthesized in a form suitable for clinical administration. The stability of the nanoparticles under physiological conditions was established by detailed in vitro studies in phosphate buffered saline (PBS) and mouse serum media. The biological efficacy of intrinsically radiolabeled 64 CuS nanoparticles was studied in C57BL/6 mice bearing melanoma tumors. The results of the biodistribution studies revealed significant tumor uptake (4.64% ± 1.71%ID/g) within 4 h post-injection (where %ID is the percent injected radioactivity dose), with good tumor-to-background contrast. Collectively, the promising results obtained in this study suggest that the concept of intrinsically radiolabeled nanoplatforms can be employed to facilitate widespread utilization of neutron-activated 64 Cu in nuclear medicine industry.

Bulletin of the Chemical Society of Japan, 2016

has received her Ph.D. degree in chemistry from University of Mumbai. She had joined Bhabha Atomi... more has received her Ph.D. degree in chemistry from University of Mumbai. She had joined Bhabha Atomic Research Centre, India as a K. S. Krishnan Research Associate and later promoted as a scientist in Radiation and Photochemistry Division in the same institute. Her research work is involved in developing organoselenium compounds as new class of antioxidants, which shows both free radical scavenging and glutathione peroxidase enzyme mimicking activity that enables higher antioxidant/ radioprotection activity even at low concentration. K. Indira Priyadarsini Dr. K. Indira Priyadarsini, an outstanding scientist at Bhabha Atomic Research Centre, is working in the multidisciplinary research areas of chemistry and biology on development of antioxidants and radioprotectors. Her research interests are on free radical reaction dynamics, radiation chemistry and enzyme kinetics, development of antioxidants and radioprotectors from natural products and organoselenium compounds.