LAUSR

Exploring suitable immobilization strategy to improve catalytic efficiency and reusability of cellulase is of great importance to lowering the cost and promoting the industrialization of cellulose-derived bioethanol. In this work, a layered structure with thin PEG hydrogel as inner layer and sodium polyacrylate (PAANa) brush as outer layer was fabricated on low density polyethylene (LDPE) film by visible light induced graft polymerization. Two enzymes, β-glucosidase (BG) and cellulase, were separately co-immobilized onto this hierarchical film. As supplementary of cellulase for improving catalytic efficiency, BG was in situ entrapped into inner PEG hydrogel layer during the graft polymerization from LDPE surface. After re-initiated graft polymerization of sodium acrylate on the PEG hydrogel layer, cellulase was covalently attached on outer PAANa brush layer. Owing to the mild reaction condition (visible light irradiation and room temperature), the immobilized BG could retain a high activity after the graft polymerization. The immobilization did not alter the optimal pH and temperature of BG, as well as the optimal temperature of cellulase. While the optimal pH of cellulase shift to 5.0 after immobilization. Comparing to the original activity of single cellulase system and isolated BG/cellulase immobilization system, the dual-enzyme system exhibited 82% and 20% increase in catalytic activity, respectively. The dual-enzyme system could maintain 93% of carboxymethylcellulose sodium salt (CMC) activity after repeating 10 cycles of hydrolysis and 89% of filter paper activity after 6 cycles relative to original activity, exhibiting excellent reusability. This layer co-immobilization system of BG and cellulase on polymer film displays tremendous potential for practical application in biorefinery.