| Summary: | 碩士 === 明新科技大學 === 化學工程研究所 === 95 === Lipase, being able to catalyze the hydrolysis of esters, esterification, transesterification and interesterification, is one of the most commonly used enzymes in biotransformations. Many commercially available enzymes are presented in immobilized forms for the purpose of repeated use. The enzyme loading and enzyme activity of immobilized enzymes may be affected by the characteristics of the immobilization matrix, for example, the pore geometry, pore size, porosity, specific surface area, charge distribution, and hydrophobicity. In this study, a series of organic silica with marcropores was prepared and used as lipase immobilization matrix to investigate the influence of matrix hydrophobicity to the loading and activity of lipase.
In the preparation of macroporous organic silica, polystyrene particles were served as pore templates. The polystyrene spheres were synthesized via emulsifier-free emulsification. With various agitating speed, styrene concentration and the amount of initiator, polystyrene spheres of mean particle size ranging between 120 and 170 nm were prepared.
The macroporous organic silica matrices were prepared through a sol-gel route using tetraethoxyorthosilicate and akyltriethoxysilicate as precursors. The precursors were hydrolyzed under acidic condition to form sols, followed by the mixing with polystyrene spheres. The mixture was centrifuged to allow the stacking of the polystyrene spheres. The polystyrene-organic silica gel composite formed after certain period of incubation. Subsequently, the polystyrene template was removed by dissolving in the equal volume mixture of toluene and acetone. The nitrogen adsorption/desorption curve revealed that these organic silicas contain a lot of interconnected marcopores, which was confirmed further by scanning electron microscopy. The estimated surface area of these organosilica was 137~403 m2/g, depending on the type and ratio of the precursors.
When applying these macroporous materials in lipase immobilization, enzyme loading decreased but the specific activity of lipase in creased with the increase of the alky chain length of organosilica matrices and activities were varied with the type and ratio of the organic matrix precursors, indicating that hydrophobicity of the immobilization matrix has significant influence to lipase adsorption and catalytic ability.
|
|---|
