用于酶固定化的多胺化壳聚糖基载体的合成及性能表征

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。

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

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.