Using ionic liquids to stabilize lipase within sol–gel derived silica

Ionic liquids (ILs) were used as additives to protect the inactivation of enzymes by released alcohol and shrinking of gel during the sol–gel process. The Candida rugosa lipases immobilized by using ILs in sol–gel process showed higher activity and stability than lipase immobilized without ILs. The hydrolytic and esterification activities of lipase coimmobilized with ILs were 5-fold and 16-fold greater than in silica gel without ILs. After 5 days incubation of lipase coimmobilized with 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide at 50 °C, residual activity of lipase was about 80% of initial activity, while the lipase immobilized without ILs was completely inactivated. ILs may act as a template during gelation and reduce shrinkage of gel by pore filling. They can also behave as a stabilizer to protect the enzyme from the inactivation.