Polydopamine coated magnetic-chitin (MCT) particles as a new matrix for enzyme immobilization

Chitin was used as a protective and dispersive matrix for the preparation of magnetic granules in the co-precipitation process. The easily prepared magnetic-chitin (MCT) particles with average size about 1.5 μm were modified with dopamine to be an effective enzyme immobilization matrix. Dopamine was self-polymerized and coated onto MCT, offering adherent surface for enzymes. A starch hydrolysis enzyme, α-amylase can be easily immobilized on the polydopamine coated MCT (DMCT). Glutaraldehyde treatment can further enhance the enzyme immobilization efficiency on DMCT particles. The surface immobilized α-amylase demonstrated a comparable starch hydrolysis rate as the free enzyme. However, the relative activities are greater than free enzyme over wider pH and temperature ranges. The magnetically retrievable immobilized α-amylase retained over 70% of its original activity after six times of repeated use.