Synthesis of photo-responsive chitosan-cinnamate for efficient entrapment of β-galactosidase enzyme

A modified photo-crosslinkable chitosan cinnamate (CS-CN) bio-polymer was synthesized via functionalization of the main active -NH2 and -OH groups of chitosan using cinnamoyl chloride. The chemical structure of the manufactured bio-polymer was elucidated using instrumental techniques including FTIR and NMR spectra. The obtained photo-active CS-CN was cross-linked upon irradiation with the UV light and the performed photo-crosslinking was monitored using UV-vis light spectra. Moreover, XRD and SEM were respectively utilized to investigate both crystalline and morphological structures of the cross-linked bio-polymer. The obtained CS-CN bio-polymer was successfully employed as a polymeric support for β-galactosidase immobilization via entrapment technique. The entrapped β-galactosidase maintains around 80% of its initial activity and displayed a considerable stability against temperature and pH changes in comparison with the native soluble enzyme form. In addition, the kinetic studies showed an expected elevation of Km along with lowering of vo values after immobilization reflecting a lower enzyme-substrate affinity. However, the reusability experiments indicated that the entrapped enzyme maintains approximately 88% of its activity after 8 reuse cycles, which reveal the value of the performed immobilization technique especially in economic terms.