Calcium alginate beads encapsulated PMMA-g-CS nano-particles for α-chymotrypsin immobilization

Chitosan grafted with polymethyl methacrylate (PMMA-g-CS) was prepared via a free-radicals polymerization technique as a carrier for enzyme immobilization. alpha-Chymotrypsin (CT), as an enzyme model in this study, was immobilized onto the prepared PMMA-g-CS via covalent bonding. Calcium alginate (CA) beads were developed for encapsulating PMMA-g-CS-CT to produce PMMA-g-CS-CT/CA composite beads. Morphology and size of PMMA-g-CS particles were investigated by TEM and found to be in the nanoscale. The structure and surface morphology of the beads before and after immobilization process were characterized by FT-IR and SEM, respectively. Both the bound CT content and relative activity of immobilized enzyme were measured. A higher retained activity (about 97.7%) obtained for the immobilized CT at pH 9 for 24 h. The results indicated that immobilized CT maintained excellent performance even after 25 reuses and retained 75% from its original activity after 60 days of storage at 25 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.