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.