Sol-gel entrapped Candida antarctica lipase B--a biocatalyst with excellent stability for kinetic resolution of secondary alcohols.

Sol-gel entrapment is an efficient immobilization technique that allows preparation of robust and highly stable biocatalysts. Lipase from Candida antarctica B was immobilized by sol-gel entrapment and by sol-gel entrapment combined with adsorption on Celite 545, using a ternary silane precursor system. After optimization of the immobilization protocol, the best enzyme loading was 17.4 mg/g support for sol-gel entrapped lipase and 10.7 mg/g support for samples obtained by entrapment and adsorption. Sol-gel immobilized enzymes showed excellent values of enantiomeric ratio E and activity when ionic liquid 1-octyl-3-methyl-imidazolium tetrafluoroborate was used as additive. Immobilization increased the stability of the obtained biocatalysts in several organic solvents. Excellent operational stability was obtained for the immobilized lipase, maintaining unaltered catalytic activity and enantioselectivity during 15 reuse cycles. The biocatalysts were characterized using scanning electron microscopy (SEM) and fluorescence microscopy. The improved catalytic efficiency of entrapped lipases recommends their application for large-scale kinetic resolution of optically active secondary alcohols.