Functionalization of Cellulose Nanofibers for Enhanced Immobilization of Recombinant Lipase in Palm Oil Hydrolysis
Abstract
The utilization of cellulose nanofiber (CNF) as a support matrix for enzyme immobilization demonstrates significant promise for biocatalytic application. This research focuses on synthesis and stepwise functionalizing CNF using 3-aminopropyltriethoxysilane (APTES), glutaraldehyde, nitrilotriacetic acid (NTA), and nickel ions to achieve oriented immobilization of histidine-tagged (His-tagged) recombinant lipase ITB 1.2. The functionalization steps were systematically characterized to confirm the formation of specific chemical bonds. The effect of fiber diameter on enzyme immobilization efficiency was investigated, revealing an enzyme loading capacity of 21.53 mg/g after 24 hours. The immobilization yield reached 90.4% and 88% for CNFs with diameter of 660 nm and 800 nm, respectively. The corresponding catalytic activities were 94.41 U/mg and 104.81 U/mg. The immobilized enzyme was applied in a hydrolysis reaction using a rotating bed reactor at varying rotational speeds of 400, 500, and 600 rpm, resulting in hydrolysis efficiencies of 40%, 57%, and 63%, respectively.