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Satpati G.G.,University of Calcutta | Mallick S.K.,Center for Research in Nanoscience and Nanotechnology | Pal R.,University of Calcutta
Biotechnology and Bioprocess Engineering

A simple and high-throughput method for determining in situ intracellular neutral lipid accumulation in Chlorella ellipsoidea and Chlorococcum infusionum with flow cytometry and confocal microscopy was established by employing different solvents and a lipophilic dye, Nile red. Seven different organic solvents, acetic acid, dimethyl sulfoxide (DMSO), acetone, methanol, ethanol, n-hexane, and chloroform at different concentrations ranging from 0 to 80% (v/v) were tested. The fluorescence signal for neutral lipids was collected with a 586/42 emission filter (PE-A) and the maximum fluorescence intensity (% grandparent) was measured as 74.01 ± 4.82% for Chlorella and 70.1 ± 5.52% for Chlorococcum at 30% acetic acid (v/v). The statistical analysis of Nile red-stained cells showed a high coefficient of variation (CV), standard deviation (SD), mean, and median values in the acetic acid-based staining method, followed by DMSO, n-hexane and chloroform. Confocal microscopy revealed a high rate of accumulation of cytosolic neutral lipids when stained with Nile red and other organic solvents. Higher lipid accumulation in Fesupplemented conditions was also detected and a maximum lipid content of 57.36 ± 0.41% (4-fold) in Chlorella and 48.20 ± 0.43% (4-fold) in Chlorococcum were measured at 0.001 g/L of ferrous sulfate (FeSO4). High fluorescence intensity (75.16 ± 0.24% in Chlorella and 72.24 ± 1.07% in Chlorococcum) in Fe-treated cells confirmed the efficiency of the staining procedure. © 2015, The Korean Society for Biotechnology and Bioengineering and Springer-Verlag Berlin Heidelberg. Source

Sultana J.,Center for Research in Nanoscience and Nanotechnology | Das A.,Center for Research in Nanoscience and Nanotechnology | Das A.,University of Calcutta | Saha N.R.,University of Calcutta | And 2 more authors.
Thin Solid Films

In this work, the CuO nano-powder has been synthesized by employing chemical bath deposition technique for its subsequent use to grow ultrathin film (20 nm) of p-CuO on n-Si substrate for the fabrication of p-CuO/n-Si hetero-junction diodes. The thin CuO film has been grown by employing vapour-liquid-solid method. The crystalline structure and chemical phase of the film are characterized by employing field-emission scanning electron microscopy and X-ray diffraction studies. Chemical stoichiometry of the film has been confirmed by using energy dispersive X-ray spectroscopy. The potential for photovoltaic applications of such films is investigated by measuring the junction current-voltage characteristics and by extracting the relevant parameters such as open circuit photo-generated voltage, short circuit current density, fill-factor and energy conversion efficiency. © 2016 Elsevier B.V. Source

Guria M.K.,University of Calcutta | Guria M.K.,Center for Research in Nanoscience and Nanotechnology | Guha A.K.,Indian Association for The Cultivation of Science | Bhattacharyya M.,University of Calcutta | Bhattacharyya M.,Center for Research in Nanoscience and Nanotechnology
Journal of Environmental Chemical Engineering

Chromium (Cr) resistant fungal strain capable of reducing toxic hexavalent chromium to non-toxic trivalent form was isolated from tannery effluent. The strain belonged to the genus Fusarium as concluded on the basis of sugar utilization and molecular profiling studies. The Translation Elongation Factor 1-α (TEF) gene sequence of the strain was identified with the accession number JX170375 in NCBI. The biotransformation of Cr(VI) to Cr(III) was optimized by the following physico-chemical parameters: incubation temperature: 25 C, incubation time: 72 h and initial pH: 5.0. Chromium reduction efficiency of the strain was observed to be 100% in growth medium after 72 h of incubation. Proteomic profiling indicated a number of proteins to be down regulated in the fungal cell on exposure to chromium. Atomic force, confocal laser scanning and scanning electron micrographs revealed enhanced surface roughness index (5.2 ± 0.2 nm to 11.53 ± 0.3 nm), significant swelling and formation of cage like structures on the cell surface induced by the presence of Cr in growth medium. Thus biotransformation of Cr(VI) in industrial waste achieved with the isolated Fusarium sp. MMT1 strain, utilizes a green technique which is immensely beneficial for bioremediation. © 2014 Elsevier Ltd. Source

Khan A.,Center for Research in Nanoscience and Nanotechnology | Manna K.,Center for Research in Nanoscience and Nanotechnology | Das D.K.,Center for Research in Nanoscience and Nanotechnology | Kesh S.B.,Center for Research in Nanoscience and Nanotechnology | And 10 more authors.
Free Radical Research

Radioprotective action of gossypetin (GTIN) against gamma (γ)-radiation-induced oxidative stress in liver was explored in the present article. Our main aim was to evaluate the protective efficacy of GTIN against radiation-induced alteration of liver in murine system. To evaluate the effect of GTIN, it was orally administered to mice at a dose of 30 mg/kg body weight for three consecutive days prior to γ-radiation at a dose of 5 Gy. Radioprotective efficacy of GTIN were evaluated at physiological, cellular, and molecular level using biochemical analysis, comet assay, flow cytometry, histopathology, immunofluorescence, and immunoblotting techniques. Ionizing radiation was responsible for augmentation of hepatic oxidative stress in terms of lipid peroxidation and depletion of endogenous antioxidant enzymes. Immunoblotting and immunofluorescence studies showed that irradiation enhanced the nuclear translocation of nuclear factor kappa B (NF-B) level, which leads to hepatic inflammation. To investigate further, we found that radiation induced the activation of stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK)-mediated apoptotic pathway and deactivation of the NF-E2-related factor 2 (Nrf2)-mediated redox signaling pathway, whereas GTIN pretreatment ameliorated these radiation-mediated effects. This is the novel report where GTIN rationally validated the molecular mechanism in terms of the modulation of cellular signaling system instead of This is the novel report where GTIN is rationally validated in molecular terms to establish it as promising radioprotective agents. This might be fruitful especially for nuclear workers and defense personnel assuming the possibility of radiation exposure. © 2015 Informa UK, Ltd. Source

Chatterjee R.,University of Calcutta | Dey T.K.,University of Calcutta | Dey T.K.,Center for Research in Nanoscience and Nanotechnology | Ghosh M.,Center for Research in Nanoscience and Nanotechnology | And 2 more authors.
Food and Bioproducts Processing

The functional characteristics which include protein solubility at different pH, emulsifying and foaming properties, degree of hydrolysis, molecular weight distribution, antioxidant and ACE inhibitory activity of sesame protein hydrolysates prepared with pepsin, papain and alcalase enzymes were evaluated. The rate of degree of hydrolysis was found to reach maximum (25-30%) within the first time fragment i.e 10 min but 80% of hydrolysis was obtained in 120 min with alcalase. SDS-PAGE of hydrolysates with papain, pepsin and alcalase evinced bands of low molecular weight protein of 14.3 kDa and even lower for alcalase treatment of 120 min. Hydrolysates so formed were of improved functional properties as evident from emulsifying and foaming property. Hydrolysis with different proteases enhanced the protein solubility significantly at pH 7.0. Antioxidative assay revealed radical scavenging activity of the hydrolysates with papain hydrolysates showing maximum antioxidative efficacy. The ultra-filtered peptide fractions which showed comparable ACE inhibitory activity were sequenced by MALDI-TOF and matched to that of previously identified ACE inhibitory peptides. The results corroborate the ACE inhibitory effect of the peptides. Hence, these highly bioactive protein hydrolysates produced from waste sesame meals can be successfully employed in various functional food formulations. © 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Source

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