Sekhar Bhattacharjee

Modulatory role of quercetin against gamma radiation-mediated biochemical and morphological alterations of red blood cells

Abstract Purpose: The present work was intended to evaluate the radioprotective effect of quercetin against gamma radiation-induced oxidative stress on red blood cells (RBC). Materials and methods: Swiss albino male mice were treated with quercetin (100 mg/kg body wt) for three consecutive days prior to 5 Gy 60Co-gamma irradiation. RBC was isolated to estimate the level of intracellular reactive oxygen species (ROS), membrane lipid peroxidation (LPO), intracellular reduced glutathione (GSH), mean corpuscular hemoglobin concentration (MCHC), osmotic fragility and morphological alterations by atomic force microscope (AFM). Results: Irradiation increased intracellular ROS and membrane LPO whereas it decreased the intracellular GSH. Quercetin pretreatment ameliorated these alterations. The MCHC value decreased after irradiation whereas quercetin pretreatment restored it. The average osmotic fragility (H50) and the maximum rate of hemolysis (dH/dC)max increased after irradiation. Quercetin pretreatment decreased the H50 and (dH/dC)max. The AFM study showed that irradiation transformed RBC from biconcave to echinocytes, increased their surface roughness and decreased the vertical distance whereas pretreatment of quercetin significantly prevented both the alterations. Conclusions: Gamma radiation produced ROS and LPO which rendered oxidative stress and ultimately damaged RBC whereas quercetin ameliorated these changes and protected RBC from radiation-mediated damage.

Laccase Incorporated into PEG-PLA Polymer as Active and Stable Biocatalyst for Ionic Liquids Media

Laccase Y20 (EC.1.10.3.2) was coated with poly (ethylene glycol)-block-polylactide (PEG-PLA, MW = 27680) via water-in-oil emulsion, and the activity and stability of the resulting PEG-PLA-laccase complex have been compared to those for the native laccase and lyophilized native laccase in an ionic liquid (IL) [C2mim][PF6] (1-ethyl-3-methylimidazolium hexafluorophosphate. The formation of spherical PEG-PLA-laccase complex of 330-480 nm was demonstrated by scanning electron microscopy. This polymer-laccase complex retained most of its enzymatic catalytic activity and exhibited excellent storage stability in IL, with over 70% of its initial activity retained after 12 days of storage in IL at 40 °C, whereas it was about 20% for native laccase under the identical conditions. This strategy could be employed to fabricate polymer based composites materials with novel biological functions.

Utilisation of eggshell membrane as an adsorbent for carbon dioxide

Carbon dioxide (CO2) is a major greenhouse gas responsible for global warming. This work aims to explore a cheap and easy way for CO2 adsorption from the atmosphere, by using an eggshell membrane. Eggshell membrane could be used up to four times with intermediate regeneration with acetic acid solution. Atomic absorption spectrophotometer (AAS) analysed the amount of CO2 adsorbed as equivalent calcium (Ca) present in calcium carbonate (CaCO3). An average of 6824 mg COCO2 could be adsorbed per g of eggshell membrane. Scanning electron micrograph (SEM) was used to analyse the surface morphology of the fresh and regenerated eggshell membrane.

Kinetic Studies on Gold Nanoparticle Formation in Aqueous Medium

Extensive research data were published in the last decade on synthesis, characterization and application of AuNP for drug delivery and protein conjugation. Gold nanoparticles were synthesized by the well-known citrate reduction (Turkevitch) method. Precursor concentrations were measured by UV-Vis spectroscopy and iodometric estimation methods. During reaction surface plasmon resonance (SPR) peaks of the reaction medium decreased from 556.5 nm to 527.2 nm in about 300s. Experimental data on time-concentration profiles of the precursor in the reaction medium were used to calculate pseudo-first order rate constant (0.0178± 0.002 s-1). Atomic Force Microscopy (AFM) was used for morphological characterization of the nanoparticles.

Ionic Liquid – Assisted Synthesis and Characterization of Cerium Oxide Nanocubes for Degradation of Methylene Blue

Cerium Oxide (CeO2) nanocubes are synthesized by using hydrothermal treatment method in the presence of four different types of ionic liquid such as acetate anion, phosphate anion, and dicyanamide anion. Ceria nanocubes has been consisted with average size of 16 to 31 nm in diameter and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), and surface analyzer and porosimetry analysis (ASAP). Ceria nanocubes have higher photocatalytical ability in the degradation of methylene blue as compared to commercial ceria nanoparticles which are confirmed through ultraviolet-visible spectroscopy (UV/Vis).

KINETICS OF ALKALINE HYDROLYSIS OF ISOAMYLACETATE

ABSTRACT The theory of mass transfer accompanied by chemical reaction has been used to determine the kinetics of alkaline hydrolysis of isoamylacetate. The rate constant for the alkaline hydrolysis is around 9.52 cm3/(mole)(sec). This is much lower than the rate constant for alkaline hydrolysis of n-amyl acetate, which is about 85 cm3/(mole)(sec). The presence of an electrolyte like sodium chloride in the aqueous phase reduced the rate of extraction to some extent. The rates of extraction with sodium chloride in the aqueous phase and the corresponding rate constant values have been reported.