Biomimetic Synthesis Of SiO₂Immobilizing Lipase

Immobilized enzyme was better than free enzyme in thermal stability、the pH stability、repeated used as well as catalyzed easily separated and so on.so It has been widely used in biocatalysis, biosensors, biochips, biological probes, as well as food and many other fields of engineering, environmental protection, energy development. L-proline has used as a template and the silica spheres had prepared by the method of biomimetic synthesis, the lipase immobilized on this vector and the enzymatic properties of immobilized lipase has studied in this article.L-proline had used as a template, biomimetic synthesis of silica spheres. The products were characterized by the field emission scanning electron microscope (FE-SEM), thermal gravimetric analysis (TGA), rapid surface/pore structure analyzer, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). FE-SEM, FT-IR characterization results showed that the formation process of silica microspheres:TEOS in the template molecules under the action of L-proline hydrolysis generated containing a large number of-NH2and-Si-OH SiO2hybrid microspheres, the SiO2hybrid microspheres had been SiO2microspheres calcined at600℃, TGA characterization results showed that SiO2microspheres with good thermal stability, The XRD results showed that SiO2microspheres of amorphous structure; nitrogen adsorption characterization of SiO2microspheres with a two-dimensional cylindrical pore mesoporous structure. Based on characterization results, the formation mechanism of the silica spheres had further explored.Lipase immobilized on silica microspheres by FT-IR characterization shows two-dimensional cylindrical pore mediated hole. The influence of fixed had analyzed by the ways of enzyme concentration, temperature, pH, and adsorption fixed-time.The results showed that the optimal conditions for the immobilized lipase:the enzyme concentration5mg/mL, adsorption temperature30℃, the reaction time of7h, pH8.0, the highest solid loading rate up to82.3%, the activity of1067U/g carrier. By response surface experimental design optimized for the three conditions of enzyme concentration, adsorption time, pH, the best combination of the three conditions:enzyme concentration4.96mg/mL the adsorption time was7.77h, pH7.26.Under these conditions, the theory of the lipase immobilized was87.48%. L-proline as a template Biomimetic Synthesis of silica microspheres as a carrier to get the basic enzymatic properties of immobilized lipase. Free lipase immobilization of silica spheres and the thermal stability of the enzyme, the pH stability of enzyme, metal ion tolerance of organic solvent tolerance, operational stability and storage stability were improved. The immobilized enzyme optimum temperature was40℃,10℃higher than the free enzyme. It remained high vitality of the immobilized enzyme within30癈～50癈The immobilized enzyme has more wider than the free enzyme in the range of reaction temperature. The heat inactivation phenomenon of Immobilized Lipase has weakened.The optimum pH of Free enzyme was7.5, with higher activity in the range of pH7～8, The optimum pH of Immobilized enzyme was7.5, with higher activity in the range of pH7.5～8.5(Relative activity was greater than80%,) It showed that Enzyme immobilized after less affected by the micro-environmental pH, the applicable pH range is significantly wider than the free enzyme. Metal ions effected the immobilized enzyme was as similar as the free enzyme. However, the immobilized enzyme activation and inhibition become more significant, Mg2+and Cu2+on the enzyme activity has little effect, Enzyme activity remained at more than90%, Mn2+, Ba2+, and Cr3+great influence on the enzyme, the relative enzyme activity decreased to below50%, of which the largest of the impact of Zn2+on the enzyme. In addition, the immobilized lipase had the high performance of in organic solvent tolerance、better response and good storage stability.