The adsorption of alpha-chymotrypsin (alpha-CT) on Al-containing mesoporous materials based on SBA-15 topology was investigated. The insertion of various amounts of aluminium was achieved using the two-step (pH-adjusting) method and the physico-chemical properties of these materials were characterized by small angle X-ray diffraction, nitrogen adsorption/desorption isotherm curves and (27)Al MAS NMR spectroscopy, ammonia adsorption microcalorimetry and chemical analyses. The amount of adsorbed enzyme was found to be dependent on the Si/Al ratio of solid surfaces, pH of adsorption and, in the case of Al-containing material, on the ionic strength. Various mechanisms of adsorption are discussed. The activity of immobilized alpha-CT was examined using the transesterification of N-acetyl-L-phenylalanine ethyl ester with 1-propanol as test-reaction. The catalytic efficiency is strongly dependent on the nature of the support. In order to reduce the leaching of enzyme from the support surface and improve its reusability, cross-linking of the adsorbed enzyme was carried out by glutardialdehyde. In general, these mesoporous silica materials are attractive candidates for enzyme immobilization and biomedical applications due to their high surface area, tunable surface properties and pore size, large pore volume and biocompatibility.
Effect of chemical composition of SBA-15 on the adsorption and catalytic activity of alpha-chymotrypsin
Secundo Francesco;
2011
Abstract
The adsorption of alpha-chymotrypsin (alpha-CT) on Al-containing mesoporous materials based on SBA-15 topology was investigated. The insertion of various amounts of aluminium was achieved using the two-step (pH-adjusting) method and the physico-chemical properties of these materials were characterized by small angle X-ray diffraction, nitrogen adsorption/desorption isotherm curves and (27)Al MAS NMR spectroscopy, ammonia adsorption microcalorimetry and chemical analyses. The amount of adsorbed enzyme was found to be dependent on the Si/Al ratio of solid surfaces, pH of adsorption and, in the case of Al-containing material, on the ionic strength. Various mechanisms of adsorption are discussed. The activity of immobilized alpha-CT was examined using the transesterification of N-acetyl-L-phenylalanine ethyl ester with 1-propanol as test-reaction. The catalytic efficiency is strongly dependent on the nature of the support. In order to reduce the leaching of enzyme from the support surface and improve its reusability, cross-linking of the adsorbed enzyme was carried out by glutardialdehyde. In general, these mesoporous silica materials are attractive candidates for enzyme immobilization and biomedical applications due to their high surface area, tunable surface properties and pore size, large pore volume and biocompatibility.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
