Synthesis and characterization of carboxymethyl cellulose-silver nanoparticle (AgNp)-silica hybrid for amylase immobilization
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Carboxymethyl cellulose-silver nanoparticle (AgNp)-silica hybrids have been synthesized in a modified Stöber process. The hybrid synthesis was optimized to obtain an efficient immobilization matrix for diastase alpha amylase, a multimeric enzyme of high technological significance. The synthesized hybrids were characterized using FTIR, XRD, SEM, TGA and BET studies. The enzyme immobilization was done by adsorption and using the immobilized enzyme, the hydrolysis of soluble starch has been optimized in comparison to free enzyme. The optimum usable pH for the immobilized enzyme ranged from pH 4 to 5, while pH 5 was optimum pH for the free enzyme activity. The kinetic parameters for the immobilized, (K M = 3.4610 mg ml−1; V max = 6.3540 mg ml−1 min−1) and free enzyme (K M = 4.1664 mg ml−1; V max = 4.291 mg ml−1 min−1) hydrolysis indicated that the immobilization at the nanohybrid has significantly improved the catalytic property of the enzyme. In the immobilized state, the enzyme remained usable for many repeated cycles like our previous material, gum acacia-gelatin-AgNp-silica. Storage experiments indicated that the immobilization has increased the stability of the enzyme and also that AgNps play a role in stabilizing the immobilized enzyme.
KeywordsCarboxymethyl cellulose Silica Silver nanoparticle Amylase Immobilization
The authors are grateful to the University Grants Commission, New Delhi India for the financial support to carry out this research work. IR, SEM and XRD facilities are acknowledged to Indian Institute of Mines, Dhanbad, Indian Institute of Technology Karagpur and National Centre of Experimental Mineralogy and Petrology, University of Allahabad respectively. Authors thank Dr. Anjana Pandey, Centre for Biotechnology, University of Allahabad, India for gifting dialysis bags.
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