Covalent immobilization of trypsin on to siliceous mesostructured cellular foams to obtain effective biocatalysts

The properties of siliceous mesostructured cellular foams (MCF) with the surface functionalised using different organosilanes to immobilize covalently trypsin have been studied. Four organosilanes were applied: 3-aminopropyltriethoxysilane, 2-aminoethyl-3-aminopropylmethyldimethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane and 3-glicydoxypropyl-triethoxysilane. The samples modified using alkylamines were further activated with glutaraldehyde (GLA), a cross-linker. Commercially available silica gels and Eupergit C were used for comparison. Activity of MCF-based biocatalysts expressed in BAPNA and casein conversion, was significantly higher than of the silica gel- and Eupergit C-based counterparts. In the best systems the determined activity of trypsin was higher than of a free enzyme. The GLA-amino linkages appeared the most effective systems for the covalent immobilization of trypsin. The MCF-based preparations were notably more stable than a native enzyme at 333 K and they also showed good storage stability at 277 K. A unique porous structure of MCF was found to be a critical factor which renders siliceous mesostructured foam a very promising material for immobilization of enzymes.