Browsing by Author "Das, Anupam"

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    Ameliorated microgel for bimetallic Ag/CuO nanoparticles and their expeditious catalytic applications
    (Springer Science and Business Media Deutschland GmbH, 2023) Singh, Vinai K.; Kumar, Krishna; Das, Anupam; Tiwari, Rudramani; Krishnamoorthi, S.
    The production of a new microgel for Ag/CuO bimetallic nanoparticles and the discovery of its rapid catalytic potential in reduction of 4-nitrophenol and methylene blue dye were accomplished. The special microgel matrix of bimetallic nanoparticles was designed to reduce the reaction catalyzing time as reported by other researchers. Graphene oxide was substituted by vinylic group and participated as a monomer in polymerization of microgel. To increase the hydrophilicity of the microgel, the monomer N-hydroxymethyl acrylamide was chosen and acted as a crosslinker instead of conventional divinyl crosslinkers such as divinyl benzene and acrylamide derivatives (methylene-bis-acrylamide). Three grades of nanocomposites were optimized by changing the amount of crosslinker to achieve a suitable platform for rapid catalytic reduction of water pollutants. Microgel and bimetallic nanocomposites were vigorously characterized by Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental dispersive X-ray (EDX), X-ray diffractometry (XRD), dynamic light scattering (DLS), thermal gravimetric analysis (TGA) and ultraviolet�visible (UV�Vis) spectroscopy. The nanocomposite exhibited excellent catalytic reduction of 4-nitrophenol and methylene blue dye. The catalytic reduction showed pseudo-first-order kinetics with its k app = 10�2�s?1 and lower NaBH4 doses. These nanocomposites are excellent materials for catalytic degradation of other pollutants and efficient candidates for effluent treatment of industrial plants. Graphical abstract: [Figure not available: see fulltext.]. � 2023, Iran Polymer and Petrochemical Institute.
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    Enhancement of urease properties by introducing new interface based on pH responsive polymer-enzyme bioconjugates via grafting through-RAFT polymerization technique
    (Elsevier Ltd, 2023) Rai, Shailja; Pande, Poorn Prakash; Kumar, Krishna; Tiwari, Rudramani; Krishnamoorthi, S.; Das, Anupam; Jana, Tushar
    New interface is introduced to the enzyme by developing the linear triblock copolymer based Polymer- Enzyme Bioconjugates (PEBC) using pH responsive polymer poly (2-acrylamido-2-methylpropane sulfonic acid) (AMPS) with the help of RAFT polymerization technique involving grafting through method. This unique polymeric interface, achieved by designing PEBC employing urease as a model enzyme, has the potential to boost the catalytic properties of commercially important enzymes in robust condition. In PEBC, urease derivative was used which has been immobilized into poly (acrylamide) (PAAm) and poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS). Different grades of PEBC were synthesized by changing AMPS amount. PEBC has been characterized by NMR, FT-IR, UV�Vis. spectroscopy, powder XRD, SEM, TGA, CMC, pH-CMC, DLS, and GPC. Urea-Urease hydrolysis kinetics in buffer medium was used to examine stability over a long period of time at different pH and temperature conditions for free urease and urease enzyme present in PEBC and its catalytic activities have been verified with the help of Michaelis-Menten kinetic constant (Km). Due to a similar km value, the PEBC bonded enzyme has approximately same affinity as the free enzyme when compared. In conclusion, this technique successfully stabilizes enzymes throughout a pH range for a number of practical applications. � 2023 Elsevier B.V.