Synthesis and characterization of a novel magnetic chitosan microsphere for lactase immobilization

Abstract A novel magnetic chitosan microsphere (MCM) as a carrier was synthesized for lactase immobilization. The morphology and structure were characterized using SEM, FT-IR, XRD and VSM. The immobilization conditions, stability as well as reusability on immobilized enzyme were studied in detail. The kinetic properties were also discussed based on the experimental. The results showed that the Fe3O4 nanoparticles were successfully coated into chitosan. The as-prepared MCM exhibited smooth spherical surface and good magnetic property. Compared with free enzyme, the immobilized enzyme displayed better pH, thermal, and storage stability. The calculated Km of immobilized lactase was higher than that of the free enzyme, indicating that the affinity weakened of lactase on MCM toward the substrate during immobilization process. The activity of immobilized lactase retained over 65 % after ten cycles using, indicating that MCM was expected to be a promising carrier for enzyme immobilization.