Sucrose monolaurate synthesis with Protex 6L immobilized on electrospun TiO ₂ nanofiber

TiO ₂ nanofibers with uniform diameter about 125 nm were prepared based on sol-gel process and electrospinning technology. Protex 6L, an industrial alkaline protease, was covalently immobilized on TiO ₂ nanofiber through γ-aminopropyltriethoxysilane modification and glutaraldehyde crosslinking. With 2 (v/v)% glutaraldehyde as crosslinker, the enzyme loading is about 201 mg (g nanofiber membrane) ^-1, and the specific activity of the immobilized Protex 6L is 2. 45 μmol h ^-1 ml ^-1 mg ^-1 protein for synthesis of sucrose monolaurate from sucrose and vinyl laurate. The optimal condition for sucrose monolaurate production is 5% (v/v) water content in DMSO/2-methyl-2-butanol solvent mixture and 50°C. Under this condition, 97% conversion was achieved within 36 h by nanofibrous Protex 6L, which is corresponding to a productivity 34 times higher than that of most widely used Novozym 435. After 10 cycles reuse, nanofibrous Protex 6L retained 52. 4% of its original activity.