Novel nanostructured tin dioxide as promising carrier for Candida rugosa lipase

Abstract

This is the first report on lipase immobilization on nanostructured tin dioxide. The material was applied as a support for Candida rugosa lipase. All biocatalytic characteristics obtained for this novel biocatalyst (nano-SnO2-CRL) were compared with those for lipase immobilized on polypropylene (PP-CRL). Nano-SnO2-CRL has shown a specific activity eight times higher than that found for PP-CRL. The tin dioxide preparation preserved up to 45% of the initial lipase activity after 1h incubation at pH 10.0, while PP-CRL was completely inactivated. The immobilization on the inorganic carrier enhanced lipase thermal stability. Upon heating for 1h at 55°C, nano-SnO2-CRL retained 77% active, while PP-CRL was half inactivated. The synthetic activity and the effect of several parameters on isoamyl acetate production for both biocatalysts were evaluated. Among four tested acyl donors, acetic anhydride was the most efficient for nano-SnO2-CRL. The reaction proceeded with a high reaction rate and resulted in 88.2% yield of the target ester for 2h. Among various solvents, n-decane proved to be the best for both catalysts. The increase in the reaction temperature from 50°C to 60°C enhanced the reaction rate 1.5 and 1.7 fold, for nano-SnO2-CRL and PP-CRL, respectively. A considerable decline in activity for both enzyme preparations was observed after the second esterification run due to prolonged heating and probably also to inhibition by substrates and product.