School Of Environment And Earth Sciences

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Author: search.filters.author.Das A.

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    Degradation of chlorpyrifos in soil using laccase immobilized iron oxide nanoparticles and their competent role in deterring the mobility of chlorpyrifos
    (Elsevier Ltd, 2020) Das A.; Jaswal V.; Yogalakshmi K.N.
    Covalent-immobilization of the laccase enzyme onto the iron oxide nanoparticles was achieved using N-(3-Dimethylaminopropyl)-N?-ethylcarbodiimide hydrochloride (EDAC) as cross-linkers. The presence of sulphur moeity in the laccase immobilized nanoparticles (LNPs) observed through Scanning Electron Microscopy- Energy dispersive X-ray spectroscopy (SEM-EDS) spectra confirmed the immobilization of laccase enzyme. The TEM analysis of iron oxide nanoparticles (FNPs), chitosan coated iron nanoparticles (CNPs) and laccase immobilized nanoparticles (LNPs) confirmed their sizes around 12, 15 and 20 nm, respectively. The effect of LNPs in degrading chlorpyrifos under field conditions was studied by simulating the conditions in a column. Column A, which was used as control showed more leaching of chlorpyrifos as compared to column B containing LNPs. The sorption coefficient (Kd) value obtained for control (column A) and LNPs containing column B were 21.6 and 112.3 L/kg, respectively. LNPs altered the Kd values of soil thereby showing lesser leaching potential. Higher the Kd value, lesser will be the leaching potential in the ground water. Copper in laccase enzyme resulted in hydrolysis of chlorpyrifos. Chitosan used for coating on FNPs and soil organic matter resulted in the adsoption of chlorpyrifos. Current results will allow a better assessment of the role of LNPs as a competent deterrent in chlorpyrifos mobility and degradation.
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    Chitin and chitosan-based support materials for enzyme immobilization and biotechnological applications
    (Springer Verlag, 2019) Verma M.L.; Kumar S.; Das A.; Randhawa J.S.; Chamundeeswari M.
    Enzymes of industrial importance are primarily employed for biotechnological applications. However, high-cost and instability issues of purified enzymes hamper their usage. Multiple reuses rather than the single use is more cost-effective. A robuster bioprocess is feasible by enzyme immobilization. Performance of immobilized enzymes depends on the nature of support materials. Chitin and its derivatives-based supports offer stability and cost-effective bioprocessing. Chitosan is biocompatible, biodegradable, non-toxic and has multiple functional groups. A variety of supports such as chitosan, chitosan film, chitosan nanoparticle and chitosan nanocomposite are employed for enzyme immobilization. Chitosan bound enzymes, as compared to free enzymes, have improved the biocatalytic performances due to exceptionally high operational stability and reusability. Here we review enzymes immobilized on chitin/chitosan supporting materials with applications ranging from agriculture to drug delivery.