Topology-controlled polymer brushes on LDPE for enhanced cellulase immobilization and lignocellulose conversion.

By providing a flexible microenvironment, immobilization of cellulase on polymer brushes represents an effective strategy to improve the interactions of cellulase with the substrate in biomass conversion. However, manipulation of polymer brush morphology remains largely unexplored, owing to the lack of an effective synthesis strategy. Herein, we developed a versatile visible-light-induced graft polymerization strategy to precisely fabricate three types of polymer brushes with well-defined topologies on low-cost low-density polyethylene (LDPE) films. Benefiting from its unique three-dimensional high-density topology, linear-bottlebrush (LB) architecture exhibited a unique 3D high-density topology and achieved the highest enzyme loading capacity (0.25 mg/cm2) and favorable enzymatic activity. The reusability was also demonstrated with 70 % of its initial activity remained after 8 reuse cycles for LB architecture. Furthermore, potential of LB brush-based immobilized cellulase in simultaneous saccharification and fermentation (SSF) of corncob for bioethanol production was demonstrated with its efficiency and reusability in practical biomass conversion processes. This study provides a synthetic methodology for constructing complex biointerfaces and establishes clear structure-property relationships, offering design principles for high-performance immobilized enzyme systems and advancing sustainable biomanufacturing.