Modified chitosan microspheres in non-aggregated amylase immobilization

•Furnished novel material of uniform porosity and size from chitosan.•Microspheres chitosan has 350 mg/g amylase immobilization prospective.•Microspheres chitosan uphold the individual non-aggregated amylase and sustain conformation stability (tertiary structure).•Immobilization increases thermal stability and pH tolerance for amylase.

Immobilized enzymes are useful as reusable catalysts in industrial processes. In this study, α-amylase was used as a model enzyme to evaluate the propensity of synthesized porous chitosan microspheres as immobilization matrix. Chitosan microspheres were synthesized by grafting and covalent gelation technique using acrylamide (AAm) and glutaraldehyde (GA) as chemical agents, respectively. The synthesized chitosan-cl-poly(AAm) demonstrated amylase immobilization capacity of 350 mg/g. Furthermore, SEM results supported the porous microsphere structure for chitosan-cl-poly(AAm) with non-aggregated amylase immobilization, which accounts for comparable activity of immobilized amylase (3.28 μmol/ml/min) in contrast to free amylase (3.46 μmol/ml/min). The immobilized α-amylase was characterized for optimal pH and temperature activity and showed better resistance to temperature and pH inactivation in contrast to free amylase. The immobilized amylase retained more than 60% of its initial activity when stored at 4 °C for 30 days and retained 50% of its initial activity after seven successive repeated-use cycles. In conclusion, the study can be used as base for the immobilization of competent industrial biocatalysts in non-aggregated active structure.