Value-added utilization of nanocellulose from biomass: Curcumin-functionalized pH-responsive hydrogels for wound dressing applications

Researchers are increasingly interested in valorizing cellulose from industrial crops to create multifunctional materials for sustainable and value-added applications. In this study, a bio-based pH-responsive nanocellulose hydrogel was fabricated using dialdehyde cellulose nanofibers (DACNF) as the structural backbone, along with carboxymethyl chitosan and two representative polyphenols (tannic acid and curcumin) derived from industrial crops. The formation involved synergistic physical interactions and dynamic covalent crosslinking. The resulting hydrogel exhibited a robust three-dimensional network, high water absorption capacity, and reversible bonding characteristics, enabling pH-regulated release of curcumin. At pH 5.5, protonation of the Schiff base linkages decreases their stability, resulting in partial network relaxation and the initial release of curcumin. As the process progresses, gradual cleavage of imine bonds, together with the persistence of borate ester crosslinking, leads to a sustained and delayed release behavior. In contrast, a higher cumulative curcumin release was observed under weakly alkaline conditions (pH 7.4). The hydrogel showed excellent antibacterial activity (>99% inhibition against Staphylococcus aureus and Escherichia coli) and strong antioxidant capacity (89.57%). A feasibility assessment in vivo evaluation demonstrated enhanced wound healing, characterized by reduced inflammation and improved collagen deposition. This work highlights an effective strategy for transforming cellulose-based industrial crops into functional bioactive hydrogels with promising application potential.