rekha nagwanshi
@mphighereducation.nic.in
Assistant Professor, Chemistry
Government Madhav Science College Ujjain MP
EDUCATION
PhD, NET- CSIR, MPhil
RESEARCH INTERESTS
Photochemistry, Organic Chemistry
Scopus Publications
Scopus Publications
Yogyata Chawre, Manmohan L. Satnami, Ankita B. Kujur, Kallol K. Ghosh, Rekha Nagwanshi, Indrapal Karbhal, Shamsh Pervez, and Manas K. Deb
American Chemical Society (ACS)
Sandeep K. Vaishanav, Jyoti Korram, Tikendra K. Verma, S. K. Jadhav, Rekha Nagwanshi, and Manmohan L. Satnami
Springer Science and Business Media LLC
Lakshita Dewangan, Yogyata Chawre, Jyoti Korram, Indrapal Karbhal, Rekha Nagwanshi, Vishal Jain, and Manmohan L. Satnami
Elsevier BV
Lakshita Dewangan, Jyoti Korram, Indrapal Karbhal, Rekha Nagwanshi, Kallol K. Ghosh, Shamsh Pervez, and Manmohan L. Satnami
American Chemical Society (ACS)
Lakshita Dewangan, Jyoti Korram, Indrapal Karbhal, Rekha Nagwanshi, and Manmohan L. Satnami
American Chemical Society (ACS)
Sandeep K. Vaishanav, Jyoti Korram, Rekha Nagwanshi, Indrapal Karbhal, Lakshita Dewangan, Kallol K. Ghosh, and Manmohan L. Satnami
Springer Science and Business Media LLC
To utilize the nanomaterials as an effective carrier for the drug delivery applications, it is important to study the interaction between nanomaterials and drug or biomolecules. In this study GSH functionalized Mn2+-doped CdTe/ZnS QDs has been utilized as a model nanomaterial due to its high luminescence property. Folic acid (FA) gradually quenches the FL of GSH functionalized Mn2+ - doped CdTe/ZnS QDs. The Stern-Volmer quenching constant (Ksv), binding constant (Ks) and effective quenching constant (Ka) for the FA-QDs system is calculated to be 1.32 × 105 M-1, 1.92 × 105 and 0.27 × 105 M-1, respectively under optimized condition (Temp. 300 K, pH 8.0, incubation time 40 min.). The effects of temperature, pH, and incubation time on FA-QDs system have also been studied. Statistical analysis of the quenched FL intensity versus FA concentration revealed a linear range from 1 × 10-7 to 5.0 × 10-5 for FA detection. The LOD of the current nano-sensor for FA was calculated to be 0.2 μM. The effect of common interfering metal ions and other relevant biomolecules on the detection of FA (12.0 μM) have also been investigated. L-cysteine and glutathione displayed moderate effect on FA detection. Similarly, the common metal ions (Na+, K+, Ca2+ and Mg2+) produced minute interference while Zn2+ Cu2+ and Fe3+ exert moderate interference. Toxic metal ions (Hg2+ and Pb2+) produced severe interferences in FA detection.Graphical abstract GSH-Mn2+ CdTe/ZnS QDs based Fluorescence Nanosensor for Folic acid.
Jyoti Korram, Lakshita Dewangan, Rekha Nagwanshi, Indrapal Karbhal, Sandeep K. Vaishanav, and Manmohan L. Satnami
Elsevier
Jyoti Korram, Lakshita Dewangan, Indrapal Karbhal, Rekha Nagwanshi, Sandeep K. Vaishanav, Kallol K. Ghosh, and Manmohan L. Satnami
Royal Society of Chemistry (RSC)
An enzyme immobilized glutathione (GSH)-capped CdTe quantum dot (QD)-based fluorescence assay has been developed for monitoring organophosphate pesticides.
Neha Kandpal, Hitesh K. Dewangan, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Informa UK Limited
Abstract Kinetic studies have been performed to understand the hydrolytic potencies of oximate (2- and 4-pyridinealdoxime) and its functionalized oximate (4-(hydroxyiminomethyl)-1-alkylpyridinium bromide) ions (alkyl = C10H21 (4-C10PyOx-); alkyl = C12H25 (4-C12PyOx-)) in the cleavage of phosphate esters, diethyl p-nitrophenylphosphate (Paraoxon) and p-nitrophenyl diphenyl phosphate (PNPDPP) in a cationic (O/W) microemulsion system (ME) over a pH range 7.5 to 11.0 at 300 K. The kobs values for the reaction of paraoxon with oximate and its functionalized oximate were determined in different microemulsion composition and the kinetic rate data shows that kobs values increases with increasing water content. The specificity of different chain length of alcohols (n-butanol, n-pentanol, n-hexanol and n-octanol) was also investigated in hydrolytic reactions of paraoxon for different microemulsion composition. GRAPHICAL ABSTRACT
Lakshita Dewangan, Jyoti Korram, Indrapal Karbhal, Rekha Nagwanshi, Vinod K. Jena, and Manmohan L. Satnami
Royal Society of Chemistry (RSC)
A functionalized silver nanoparticle (AgNP) based colorimetric probe have been developed for efficient sensing of cholesterol, most important cardio-risk-marker.
Jyoti Korram, Lakshita Dewangan, Rekha Nagwanshi, Indrapal Karbhal, Kallol K. Ghosh, and Manmohan L. Satnami
Royal Society of Chemistry (RSC)
In this work, fluorescence (FL) quenching (turn-off) and recovery (turn-on) of carbon quantum dots (CQDs) in the presence of dispersed and aggregated gold nanoparticles (AuNPs) was used as a probe for monitoring the inhibition and reactivation of acetylcholinesterase (AChE).
Neha Kandpal, Hitesh K. Dewangan, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Wiley
Manmohan L. Satnami, Jyoti Korram, Rekha Nagwanshi, Sandeep K. Vaishanav, Indrapal Karbhal, Hitesh K. Dewangan, and Kallol K. Ghosh
Elsevier BV
Abstract The organophosphorus compound (OP) induced inhibition of acetylcholinesterase (AChE) and their reactivation has been monitored using gold nanoprobe. The method is based on the colour change and red shift of localized surface plasmon resonance (LSPR) absorption band of AuNPs in UV–vis region after the addition of acetylthiocholine in presence of AChE. The aggregation of AuNP is induced by the thiocholine (TCh) through Au-S binding and electrostatic force of interactions. The inhibitory attack of OPs at the active serine site of the AChE leads to the decrease in formation of TCh molecule, which consequently, prevents the aggregation of the AuNPs. Conversely, the red shift of LSPR has been regained upon the reactivation of OP inhibited AChE by oximates (2-PyOx−, 4-C12PyOx−) and salicylhydroxamate (SHA). The inhibition protocols of the AChE have been used for detection of OP pesticides. The linear range for determination of OPs was found in range of 0.30–17.30 ng mL−1 with their limit of detection being 0.13 ng mL−1, 0.37 ng mL−1, 0.42 ng mL−1 and 0.20 ng mL−1 for paraoxon, parathion, fenitrothion and diazinon, respectively. The proposed method was found to be simple, sensitive and cost effective for the determination of OPs in real water samples.
Neha Kandpal, Hitesh K. Dewangan, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Wiley
Neha Kandpal, Hitesh K. Dewangan, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Elsevier BV
Abstract Rate constants have been determined spectrophotometrically for the reaction of paraoxon, parathion and fenitrothion (OP pesticides) with oximate (Ox−) and hydroxamate (HA−) ions in aqueous and cationic vesicular media at 300K. All reactions followed the pseudo-first-order kinetics. The surface properties i.e. the critical vesicle concentration (cvc), maximum surface access (Γmax), surface pressure at the cvc (Πcvc) and minimum surface area per molecule (Amin) of vesicular surfactants dioctadecyldimethylammonium chloride (DODAC) and didodecyldimethylammonium bromide (DDAB) with Ox− and HA− ions have been evaluated by conductivity and surface tension measurements at 300 K. The standard Gibbs free energy of vesicle formation (ΔG0v), Standard Gibbs free energy of adsorption (ΔG0ad), and standard Gibbs free energy of vesicle formation per alkyl chain (ΔG0v, tail) of cationic vesicular surfactants with Ox− and HA− ions have also been evaluated. SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscope) were used to investigate the morphological behavior and size of vesicular surfactants. We observed a well-defined contour of vesicular surfactants that are mostly spherical and globular shape. The effects of vesicular morphology and chemical reactivity have been discussed.
Kumudini Chandraker, Rekha Nagwanshi, S.K. Jadhav, Kallol K. Ghosh, and Manmohan L. Satnami
Elsevier BV
Graphene oxide (GO) sheets decorated with amino acid L-cysteine (L-cys) functionalized silver nanoparticles (GO-L-cys-Ag) was synthesized by AgNO3, trisodium citrate, and NaBH4. GO-L-cys-Ag nanocomposite was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, which demonstrated that a diameter of L-cys-AgNPs compactly deposited on GO. Antibacterial activity tests of GO-L-cys-Ag nanocomposite were carried out using Escherichia coli MTCC 1687 and Staphylococcus aureus MTCC 3160 as model strains of Gram-negative and Gram-positive bacteria, respectively. The effect of bactericide dosage on antibacterial activity of GO-L-cys-Ag nanocomposite was examined by plate count, well diffusion and broth dilution methods. Morphological observation of bacterial cells by scanning electron microscope (SEM) showed that GO-L-cys-Ag nanocomposite was more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus. The above technique establish that the bactericidal property of GO-L-cys-Ag nanocomposite with wide range of applications in biomedical science.
Sandeep K. Vaishnav, Kuleshwar Patel, Kumudini Chandraker, Jyoti Korram, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Elsevier BV
The determination of thiol based biological molecules and drugs, such as cysteine (Cys) (I), α-lipoic acid (II), and sodium 2-sulfanylethane sulphonate (Mesna (III)) in human plasma are becoming progressively more important due to the growing body of knowledge about their essential role in numerous biological pathways. Herein we demonstrate a sensitive colorimetric sensor for the determination of medicinally important thiol drugs based on aggregation of the citrate capped silver nanoparticles (Ag NPs). This approach exploited the high affinity of thiols towards the Ag NPs surface which could tempt replacement of the citrate shell by the thiolate shell of target molecules, resulting in aggregation of the NPs through intermolecular electrostatic interaction or hydrogen-bonding. Because of aggregation, the plasmon band at around 400nm decreases gradually, along with the appearance of a new band connoting a red shift. The calibration curves are derived from the intensity ratios of A530/A400, which display a linear relation in the range of 1μM-150μM, 5μM-200μM and 10μM-130μM, respectively. The obtained detection limits (3σ) were found to be 1.5μM, 5.6μM and 10.2μM for compound I-III, respectively. The proposed method has been successfully applied for the detection of thiol compounds in real samples.
Sandeep K. Vaishanav, Jyoti Korram, Priyanka Pradhan, Kumudini Chandraker, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Springer Science and Business Media LLC
AbstractArsenic (As3+) is a hazardous and ubiquitous element; hence the quantitative detection of arsenic in various kinds of environmental sample is an important issue. Herein, we reported L-cysteine capped CdTe Quantum dot based optical sensor for the fluorometric detection of arsenic (III) in real water sample. The method is based on the fluorescence quenching of QDs with the addition of arsenic solution that caused the reduction in fluorescence intensity due to strong interaction between As3+ and L-cysteine to form As(Cys)3. The calibration curve was linear over 2.0 nM-0.5 μM arsenic with limit of detection (LOD) of 2.0 nM, correlation coefficient (r2) of 0.9698, and relative standard deviation (RSD %) of 5.2%. The Stern-Volmer constant for the quenching of CdTe QDs with As3+ at optimized condition was evaluated to be 1.17 × 108 L mol−1 s−1. The feasibility of the sensor has been analyzed by checking the inference of common metal ions available in the water such as K+, Na+, Mg2+, Ca2+, Ba2+, Cu2+, Ni2+, Zn2+, Al3+, Co2+, Cr2+, Fe3+ and its higher oxidation state As5+.
Graphical AbstractSchematic representation of As3+ detection by L-Cysteine capped CdTe QDs
Neha Kandpal, Hitesh K. Dewangan, Rekha Nagwanshi, Sandeep K. Vaishanav, Kallol K. Ghosh, and Manmohan L. Satnami
Wiley
The hydrolysis of carboxylate esters viz. p-nitrophenyl acetate (PNPA), p-nitrophenyl butyrate (PNPB) and p-nitrophenyl octanoate (PNPO) in the presence of cationic vesicles of the surfactant dioctadecyldimethylammonium bromide (DODAC) by different hydroxamate ions i.e. acetohydroxamate (AHA−), benzohydroxamate (BHA−) and salicylhydroxamate (SHA−) were studied. The kinetic data was supported by spectrophotometric measurements. The effects of vesicular size on the reaction have been discussed. The differential reactivity under endo- and exovesicular conditions has also been evaluated. Critical vesicle concentrations (CVC) of cationic vesicular surfactants were determined from conductometric and fluorimetric measurements at 300 K. Fluorescence probe pyrene and pyrene-1-carboxaldehyde have been used for determination of CVC. Further, thermodynamic parameters viz. Standard Gibb’s energy (∆G°), enthalpy (∆H°), and entropy (∆S°) of vesicles has also been evaluated within a temperature range of 303.15–328.15 K.
Hitesh K. Dewangan, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Springer Science and Business Media LLC
The nucleophilic hydrolysis of paraoxon, parathion and fenitrothion by pyridine oximate (PyOx−) and hydroxamate (PyHA−) has been studied in aqueous and cationic micellar media. A noticeable kinetic changes has been observed at pH > pKa due to effective nucleophilicity of oximate (–CH=NO−) and hydroxamate (–CONHO−) functions. The Ox− nucleophile shows large reactivity than corresponding HA−. The reactivity of nucleophiles toward the electrophilic center of P=O and P=S bond of phosphate ester shows prominent effect in the presence of cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) micelles than aqueous media. The adjacent lone pair of electron in nitrogen atom on the nucleophile moiety of 2-PyOx and 2-PyHA helps to augment the reactivity compared to presence in remote of 4-PyOx and 4-PyHA nucleophile. The application of the pseudophase model of micellar catalysis showed that the ratio k2m/k2w is higher for the reaction of esters.Graphical Abstract
Manmohan L. Satnami, Hitesh K. Dewangan, and Rekha Nagwanshi
Wiley
The hydrolysis reaction of O,O-diethyl O-p-nitrophenylphosphate (Paraoxon) with the octanohydroxamate ion (OHA−) was studied in a cationic oil-in-water (O/W) microemulsion system over a pH range 7.5–12.0 at 300 K. The O/W systems are stabilized by using cationic surfactant, cetyltrimethylammonium bromide (CTAB), and n-butanol as cosurfactants. In a microemulsion, the rate enhancement by OHA− is greater toward the cleavage of paraoxon than its spontaneous (2.1 × 107 s−1) hydrolysis. The kobs values for the reaction of paraoxon with OHA− were determined in different microemulsion compositions with varying chain length of alcohols (n-butanol, n-pentanol, n-octanol, and n-dodecanol) and alkanes (n-hexane, n-heptane, and n-decane). The effects of water content, pH, and size of the oil pool have been discussed.
Manmohan L. Satnami, Hitesh K. Dewangan, Neha Kandpal, Rekha Nagwanshi, and Kallol K. Ghosh
Elsevier BV
Abstract The surface properties and mixed micellization behavior of cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DTAB) with octanohydroxamic acid (OHA) have been investigated by means of conductivity and surface tension measurements in aqueous solution and borate buffer at 300 K. The critical micelle concentration (cmc), surface properties such as maximum surface access ( Γ max ), surface pressure at the cmc ( Π cmc ) and minimum surface area per molecule ( A min ) has been determined. The standard Gibbs free energy of micellization (ΔG m 0 ), standard Gibbs free energy of adsorption (ΔG ad 0 ), and standard Gibbs free energy of micellization per alkyl chain (ΔG m, tail 0 ) of cationic surfactant with OHA have been evaluated. The fluorescence quenching technique was used to estimate the aggregation number ( N agg ) and packing parameter ( P ) for determining the structural feature of cationic surfactants in the presence of octanohydroxamic acid. The hydrolytic reaction of paraoxon with octanohydroxamic acid was studied under a cationic micellar system by using OHA − at 9.2 pH and 300 K. The variations of surface properties from aqueous medium to the reaction condition have also been discussed. Pseudophase model (PPM) has been fitted for the quantitative treatment of the data.
Sandeep K. Vaishanav, Kumudini Chandraker, Jyoti Korram, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Elsevier BV
Abstract Investigating the protein nanoparticle interaction is crucial to understand how to control the biological interactions of nanoparticles. In this work, Model protein Bovine serum albumin (BSA) was used to evaluate the process of protein adsorption to the gold nanoparticles (GNPs) surface. The binding of a model protein (BSA) to GNPs was investigated through fluorescence quenching measurements. The strong affinities of BSA for GNPs were confirmed by the high value of binding constant ( K s ) which was calculated to be 2.2 × 10 11 L/mol. In this consequence, we also investigated the adsorption behavior of BSA on GNPs surface via UV–Vis spectroscopy. The effect of various operational parameters such as pH, contact time, initial BSA concentration, and temperature on adsorption of BSA was investigated using batch adsorption experiments. Kinetics of adsorption was found to follow the pseudo-second order rate equation. The suitability of Freundlich and Langmuir adsorption models to the equilibrium data was investigated. The equilibrium adsorption was well described by the Freundlich isotherm model. The maximum adsorption capacity for BSA adsorbed on GNPs was 58.71 mg/g and equilibrium constant was 0.0058 calculated by the Langmuir model at 298 K and pH = 11.0. Thermodynamic parameters showed that the adsorption of BSA onto GNPs was feasible, spontaneous, and exothermic.
Sandeep K. Vaishanav, Jyoti Korram, Rekha Nagwanshi, Kallol K. Ghosh, and Manmohan L. Satnami
Springer Science and Business Media LLC
Protein Quantum dots interaction is crucial to investigate for better understanding of the biological interactions of QDs. Here in, the model protein Bovine serum albumin (BSA) was used to evaluate the process of protein QDs interaction and adsorption on QDs surface. The modified Stern-Volmer quenching constant (Ka), number of binding sites (n) at different temperatures (298 308 and 318 K ± 1) and corresponding thermodynamic parameters (ΔG < 0, ΔH < 0, and ΔS > 0) were calculated. The quenching constant (Ks) and number of binding sites (n) is found to be inversely proportional to temperature. It signified that static quenching mechanism is dominant over dynamic quenching. The standard free energy change (ΔG < 0) implies that the binding process is spontaneous, while the enthalpy change (ΔH < 0) suggest that the binding of QDs to BSA is an enthalpy-driven process. The standard entropy change (ΔS > 0) suggest that hydrophobic force played a pivotal role in the interaction process. The adsorption process were assessed and evaluated by pseudofirst-order, pseudosecond-order kinetic model, and intraparticle diffusion model.