Influence of the porous texture of silica gels on the enzymatic activity of lipases in esterification reactions

Pseudomonas Cepacia lipases were encapsulated in hybrid silica-polyvinyl alcohol gels, which were dried either supercritically in order to form aerogels or by evaporation so as to obtain xerogels In each case, the catalytic activity of the encapsulated enzymes was studied and compared to free enzyme biocatalysis. This study demonstrates that the activity of the enzyme is increased when the procedure used allows it to resist capillary stresses occurring during the drying of the gel. That is, esterification rates are higher when the gels are synthesized with a base catalyst, such as NaF, in the presence of polyvinyl alcohol and then dried supercritically. (C) 2001 Elsevier Science B.V. All rights reserved.