Abstract: Alkaline phosphatase expressing in recombinant E. coli was immobilized on Chitosan-poly (lactic-co-glycolic acid) by using glutaraldehyde as cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were obtained through single factor and orthogonal experiment. The results showed that the best condition of immobilization was optimal when the CS-PLGA nanoparticles concentration was 50 mg, the volume fraction of glutaraldehyde was 4%, cross-linked time was 2.0 h and immobilized time was 9.0 h, the immobilized enzyme can keep activity about 76.2%. At the same time the optimal temperature, the optimal pH, the thermal stability and pH stability of alkaline phosphatase were comparatively improved after immobilization. So it confirmed that the technology would form basis of the further application of immobilized alkaline phosphatase.

Key words: Nanoparticle, Chitosan-poly(lactic-co-glycolic acid), Alkaline phosphatase, Immobilized enzyme