Green-synthesized ZnO nanoparticles incorporated into cellulose films: structural, optical, antibacterial, and cytocompatibility evaluation for wound dressing applications

• Green synthesis of ZnO nanoparticles using Hibiscus sabdariffa extract as a sustainable reducing and efficient capping agent. • Antimicrobial cellulose films were successfully fabricated and reinforced by green synthesized ZnO nanoparticles for biomedical use. • Structural and optical characterizations confirmed uniform ZnO dispersion in cellulose matrix and strong interfacial interactions. • ZnO–cellulose composite films exhibited strong bactericidal activity against S. aureus and E. coli bacterial strains. • Cytotoxicity and hydrogel evaluations highlighted the critical balance between antimicrobial effectiveness and biocompatibility. In this study, zinc oxide nanoparticles (ZnO NPs) were green-synthesized using Hibiscus sabdariffa extract and incorporated into cellulose-based films to enhance their structural, optical, and biological performance for wound dressing applications. Two composite formulations containing 1 wt.% and 1.5 wt.% ZnO (relative to cellulose) were fabricated and evaluated. The calcined ZnO NPs exhibited a crystallite size of 36.98 nm, confirmed by XRD, and were uniformly distributed within the cellulose matrix. UV–Vis and PL analyses revealed that the natural Hibiscus pigments contributed to improved light absorption and defect-related emissions. The films demonstrated strong antibacterial activity, with inhibition zone diameters of 23.33 mm against Escherichia coli (E. coli) and 19.67 mm against Staphylococcus aureus ( S. aureus) . MIC and MBC values ranged from 1562–3125 µg/mL depending on bacterial strain and ZnO content. Cytocompatibility tests on fibroblasts showed that incorporation of ZnO induced a moderate, time-dependent cytotoxic response, while maintaining viability levels acceptable for antimicrobial surface application. The Cel–ZnO 1.5 % film exhibits the highest swelling but the lowest moisture-retention stability. Prepared ZnO–cellulose composites provided the optimal balance of antibacterial efficacy and cytocompatibility, indicating its strong potential as a functional wound dressing material.