摘要
通过在分子筛合成过程中加入NH4F和后嫁接法,合成了氟离子改性和表面环氧功能化的MCFs泡沫状介孔分子筛,用X射线衍射(XRD)、傅里叶-红外(FT-IR)、N2吸附、热重分析(TGA)和扫描电子显微镜(SEM)对分子筛进行了表征。将MCFs介孔分子筛用于青霉素酰化酶的固定化,其中用氟离子改性的MCFs介孔分子筛制备的固定化酶得到了目前文献报道最高的表观活性,达到9104IU/g。通过在合成过程中加入NH4F,降低了MCFs介孔分子筛的粒径,增加了MCFs分子筛的窗口直径、腔体直径和孔容,但降低了MCFs分子筛的比表面积,大大提高了固定化酶的表观活性和操作稳定性,固定化酶的表观活性从4547IU/g提高到9104IU/g,循环使用5次后的操作稳定性从58%提高到80%。同时通过用γ-[(2,3)-环氧丙氧]丙基三甲氧基硅烷在MCFs分子筛表面嫁接含有环氧基的有机官能团,进一步提高固定化酶的操作稳定性,循环使用5次后的固定化酶的操作稳定性从80%提高到85%,但表观活性从9104IU/g下降到8519IU/g。
Fluorine-modified or epoxy group-functionalized mesocelluar foam silica （MCFs） mesoporous silica, synthesized with addition of NH4F or post-grafting, were characterized by XRD, FT-IR, N2 sorption, TGA and SEM. MCFs mesoporous silica were used as the supports for immobilization of penicillin G acylase （PGA）. The specific activity of PGA immobilized on Fluorine-modified MCFs mesoporous silica achieves 9 104 IU/g, which is the highest activity ever reported for carrier-bond PGA. With addition of NH4F, the particle sizes of MCFs mesoporous silica decrease, the diameters of their windows or cells and their pore volumes increase, but their specific surface areas decrease, which greatly increase the specific activity and the operational stability of immobilized PGA. Their specific activity increases from 4 547 IU/g to 9 104 IU/g, and their operational stability increases from 58% to 80% after recycled for 5 times. Epoxy group-functionalized MCFs mesoporous silica was synthesized by post-grafting with γ-glycidoxypropyltrimethoxylsilane, which further improves the operational stability of immobilized PGA from 80% to 85% after recycled for 5 times, but their specific activity decreases from 9 104 IU/g to 8 519 IU/g.
基金
高等学校博士学科点专项科研基金(20070251016)
