Polylactic Acid (PLA) Modified by Polyethylene Glycol (PEG) for the Immobilization of Lipase

This work presents a novel lipase immobilization method via polylactic acid (PLA) modified by polyethylene glycol (PEG). The immobilization performance of lipase was characterized by SEM and FTIR. The results indicated that lipase from Candida rugosa type VII was successfully immobilized on the biocompatible PLA/PEG film in the presence of 1, 6-hexamethylene diamine and glutaraldehyde. In addition, the presence of 1, 6-hexylenediamime (8%, w/w) could maintain the maximum enzymatic activity. Moreover, the optimum temperature of lipase shifted from 45 to 50 °C after immobilization. The thermal inactivation experiment illustrated that the immobilized lipase retained up to 63% of the original activity after treated at 50 °C in buffer for 120 min, significantly higher than that of the control (33%) (p < 0.05). The optimum pH value of the immobilized lipase shifted from 6.5 to 7.5. Additionally, compared with the free lipase maintaining 23% of its original activity, the immobilized lipase successfully retained up to 70% after 30 days of storage. Furthermore, the immobilized lipase displayed the excellent reusability of 82% after six cycles. In conclusion, the proposed immobilization approach developed can be potentially used as a sustainable alternative for the immobilization of lipases and the utilization of biocompatible polymer. Graphical Abstract.