Immobilized enzymes in ordered mesoporous silica materials and improvementof their stability and catalytic activity in an organic solvent

Enzyme immobilization in mesoporous materials with various pore sizes was s tudied. The size of the mesopores was controlled by means of the combinatio n of the alkyl chain lengths of surfactants and a swelling agent (triisopro pyl benzene). Enzymes were selectively adsorbed to FSM-16 and MCM-41 prepar ed with a cationic surfactant. whose pore sizes were over the molecular dia meters of the enzymes. and were not adsorbed significantly to SBA-15 prepar ed with a non-ionic surfactant. The higher adsorption as to FSM-16 or MCM-1 1 rather than on SBA-lj may be due to the ionic characteristics of the meso pore. which would be consistent with the observed larger adsorption capacit y as to the cationic pigment rather than the anionic pigment of these mater ials. Enzymes, horseradish peroxidase and subtilisin, immobilized in FSM-16 showed the best stability and peak catalytic activity in an organic solven t when the average mesopore size just exceeded the molecular diameters of t he enzymes. (C) 2001 Elsevier Science B.V. All rights reserved.