Activation of lipase by sol-gel coating with hydrophobic alkyl-substituted silicates in supercritical carbon dioxide

Background: Sol-gel entrapment of lipases is usually performed in an aqueous solution. A novel method of sol-gel coating of lipasde in supercritical carbon dioxide (SC-CO₂) is proposed. Results: Crude lipase powder (Rhizopus oryzae) coatedwith hydrophobic silicates, derived from dimethyldimethoxysilane and tetramethoxysilane in SC-CO₂ at 35 °C and 15 MPa, exhibited 5-7 times higher esterification activity than that prepared via an aqueous sol-gel route. Lipase immobilized in amethyl-substituted silica monolithwas also highly activated by sol-gel coating using the same silica precursors in SC-CO₂. Conclusion: Sol-gel coating in SC-CO₂, of lipases in powder and immobilized forms with hydrophobic alkyl-substituted silicates provides an efficient tool for the enhancement of enzymatic activities in non-aqueous media.