Recent developments in the possible use of nanoparticles for carrier of enzyme have attracted great attention. In the present study, the arsenite oxidase (AOase) enzyme capable of transforming the more toxic arsenite (As(III)] to the less toxic arsenate [As(V)] was isolated from arsenic resistant bacteria (Exiguobacterium) and partially purified. Chitosan nanoparticles were prepared on the basis of ionie gelation of chitosan with tripolyphosphate (TPP) anions. The purified AOase was immobilized efficiently by physical adsorption on to chitosan nanoparticles and were characterized for particle size, morphology, zeta potential, AOase loading efficiency and subsequent release kinetics. The chitosan nanoparticles were spherical in shape with the average diameter of 100 nm which increased to 294 nm upon successful loading of AOase. Under optimized conditions, the loading capacity of the chitosan nanoparticle was determined to be 71% for AOase. Further, immobilization also increased the stability of AOase at varying temperature (4-37 "C) and pH (5-10) for a period of 30 days with the increased activity. It also facilitated increased biotransformation of As (III) to As (V) with a potential of five times of reuse. A conceptual understanding of biological responses to AOase loaded chitosan nanoparticle is needed for the development of novel methods of drug delivery.
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