Hydrophobic silica aerogel–lipase biocatalysts: Possible interactions between the enzyme and the gel

The present study has focused on the encapsulation of the lipase from Burkholderia cepacia in an aerogel made from 80% tetramethoxysilane (TMOS) and 20% methyltrimethoxysilane (MTMS), dried by the supercritical CO2 method. Correlating modifications in the synthetic procedure of the composite gel to the catalytic activity of the aerogel-encapsulated lipase in the esterification reaction of lauric acid with 1-octanol showed that synthetic changes that improve the shrinkage resistance of the composite gel during drying, improve the enzyme activity, irrespective of the final surface functionalities present on the pore surface. The action of the lipase itself has also been examined by measuring the silica gelation times and performing enzyme thermal deactivation. These results lead us to propose a model by which the enzyme acts as a template to build the silica network, by adsorbing silica precursor molecules carrying silanol groups, on its amide bonds.