Preparation Of Dendritic Composite Silicon Oxide Carriers And Their Application In The Immobilization Of Lipase

The widespread interest in enzyme immobilization has largely been driven by the benefits of immobilized enzymes. Since the establishment of enzyme immobilization technology, considerable attention has been focused on the study of novel immobilization carrier materials. With novel structure and special characteristic, dendritic composite shows great potential application in this field. In this work, a series of novel dendritic composite silica were prepared via simple copolymerization between 3-aminopropyltriethoxysilane or the dendritic silanes A～C and tetraethyl orthosilicate. The application of these materials on enzyme immobilization was also assessed. The main contents of this paper are as follows:(1) A series of dendritic composite silica materials (F-type) were synthesized. And their application in immobilizing lipase was studied. The result shows that the branch length of dendritic carriers and the method of immobilizing lipase will affect the immobilization efficiency and the relative activity of lipase to a great extent. On the basis of the above investigation, another novel composite materials (MS-type) was designed and prepared by copolymerization of tetraethyl orthosilicate and a dendritic monomer on the surface of magnetic microparticle (Fe3O4). The immobilization experiments indicated that the MS-type carriers were much better than the F-type carriers in lipase immobilization. And the immobilized PPL by the MS-type carriers could be reclaimed more easily.(2) A J-type mesoporous material, which has an ordered hexagonal morphology, was prepared by using one anionic surfactant as the template. This type of mesoporous material has also been applied in the immobilization of PPL, and showed very good absorption ability for lipase. Its immobilization efficiency reaches 99%,while its relative activity kept about 80%. The optimal immobilization conditions were: 100 mg PPL/ 1g carrier, the stirring time: 45 min; pH 7.5, at 37℃.(3) Compared to activated carbon nanotube, the carbon nanotube composite silica has better performance in immobilizing lipase. The immobilized lipase still remains 60% activity in comparison with initial enzyme activity after recycled five times. The optimal immobilization conditions were: 40 mg PPL/ 1g carrier, the stirring time: 30 min; pH 7.0.In conclusion, this dendritic composite silica is a kind of novel valuable carrier for immobilization of enzyme and might have widespread application in this field.