用于酶固定化的多胺化壳聚糖基载体的合成及性能表征

Synthesis and Characterization of Polyethyleneaminated Chitosan Microsphere as Support for Immobilized Enzyme

以构建性能优良的壳聚糖基固定化酶载体为目的,用反相悬浮交联法制备了壳聚糖微球,以其作为固定化载体基体,进一步制备了多胺化壳聚糖载体,分别优化了壳聚糖微球环氧化及胺化反应条件。最佳环氧化条件为：n（环氧氯丙烷）∶n（壳聚糖结构单元）=10∶1、50℃反应6 h,环氧基含量达3.32 mmol/g;最佳胺化条件为：n（四乙烯五胺）∶n（环氧基）=15∶1、55℃反应6 h,载体氨基含量可达4.55 mmol/g,高于未胺化微球的2.01mmol/g。用IR、SEM、XRD等对最终产物进行了表征。结果表明,制备的多胺化壳聚糖呈单分散球形,粒径220～300μm,表面较光滑,抗酸性能显著增强。采用该载体对木瓜蛋白酶进行固定化,固定化酶表观活力最高达146 U/g,活力回收率达51%,是采用未经多胺修饰的壳聚糖微球固定化的2～3倍。

Monodispersed chitosan microspheres in the range 220 μm to 300 μm were prepared as support matrix for immobilized enzyme by phase-inversion suspension cross-linking technique firstly, then polyethyleneaminated chitosan microspheres with more amino group content and better mechanical resistance were prepared by reaction of polyethyleneamine and epoxy-activated chitosan. Preparation conditions of the immobilization support were optimized. Epoxidation was run at 50 ℃ for 6 h with molar ratio of epichlorohydrin to chitosan unit 10：1 ,and the epoxide group content was 3.32 mmol/g. Amination was carried out at 55 ℃ for 6 h with molar ratio of tetraethylene pentamine to epoxide group 15：1, and the amino group content reached 4.55 mmol/g. Structure of the product was characterized by IR,SEM and XRD. Papain was immobilized on the support. The apparent activity of the immobilized papain reached 146 U/g. The recovery of immobilized papain activity reached 51% , which was 2 -3 times that as immobilized on pure chitosan microsphere.