Synergistic Enhancement of Laccase-Cellulase via Co-Immobilization in a CMS/CPAM/PDA Hydrogel for Bamboo Pulp Fiber Flexibility

Multienzyme complexes offer synergistic effects beyond individual enzymes, but their inherent instability and low activity severely limit the practical applications. Here, a sodium carboxymethyl starch/polyacrylamide/polydopamine (CMS/CPAM/PDA) hydrogel was developed to coimmobilize cellulase and laccase via Schiff-base formation between amino groups present on the enzymes and carbonyl groups of polydopamine. Immobilized enzyme complexes exhibit higher relative activity across pH values of 3-9, improved storage stability, and enhanced thermal tolerance. Furthermore, the Cu²⁺-activated immobilized enzyme complex for bamboo fiber treatment demonstrated a 7.54-fold improvement in flexibility, attributed to the synergistic laccase-mediated lignin degradation, which enhances cellulase accessibility to the fiber surface. The application of these flexibility-enhanced bamboo pulp fibers in tissue paper manufacturing yielded a 65.31% increase in softness. The enhanced flexibility of bamboo fibers achieved through complex enzyme immobilization within a CMS/CPAM/PDA hydrogel represents a key development for the utility of bamboo in tissue products.