Immobilization of lipase within carbon nanotube-silica composites for non-aqueous reaction systems

The immobilization of lipases within sol-gel derived Silica, using multi-walled carbon nanotubes (MWNTs) as additives in order to protect the inactivation of lipase during sol-gel process and to enhance the stability of lipase, was investigated. Three sol-gel immobilized lipases (Candida rugosa. Candida antarctica type 13, Thermomyces lanuginosus) with 0.33% (w/w) MWNT showed Much higher activities than lipase immobilized Without MWNT. The influence of MWNT content and MWNT shortened by acid treatment in the sol-gel process on the activity and stability of immobilized C rugosa lipase was also studied. In hydrolysis reaction, immobilized lipase containing 1.1% pristine MWNT showed 7 times higher activity than lipase immobilized without MWNT. The lipase coimmobilized with 2.7% shortened MWNT showed 10 times higher activity in esterification reaction, compared with lipase immobilized Without MWNT. The lipase coimmobilized with 2.7% shortened MWNT retained 96% of initial activity after 5 times reuse, while the lipase immobilized without MWNT was fully inactivated under the same condition. (C) 2009 Elsevier B.V. All rights reserved.