Entrapment of enzymes in nanoporous sol-gels

The prerequisite for many successful enzyme-based biotechnologies is the preparation of highly stable and active biocatalysts, which can be achieved effectively by immobilization. This chapter introduces the immobilization of enzymes by entrapment in nanoporous silica particles made in a sol-gel process. These easily tailorable materials have been proven very beneficial for a broad variety of applications of biocatalysts. Besides the spatial confinement in silica sol-gels, another advantage is given by the easy possibility of fine-tuning the physicochemical properties of the matrix itself to provide the ideal environment for the reaction and the biocatalyst. Preparation details are demonstrated using the process of immobilizing a lipase in a sol-gel matrix, which is chemically modified by using methyl-, ethyl-, propyl-, and i-butyltrimethoxysilane. The transesterification of canola oil with methanol is used as a model reaction.