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.