Encapsulation of ZnO-NPs, tannic acid, and β-carotene into cellulose coated polydopamine bionanoplatform: Fabrication, characterization, antimicrobial, and in vitro wound healing evaluation.

In this work, we report the fabrication of five novel bionanoplatforms derived from cellulose nanofibers (CNF) with effective antimicrobial activity, desired cytocompatibility, and promising wound-healing capability. CNF was functionalized via oxidation by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), coated with polydopamine (PDA), followed by decoration with ZnO nanoparticles (ZnO-NPs) prepared via ultrasound-mediated co-precipitation, creating a bioactive nanoplatform of ZnO@CNF-coated PDA (CNF2). Tannic acid (TA) and β-carotene (BC) were immobilized on CNF2. FT-IR and XPS confirmed the scaffold's chemical composition, while the XRD verified the functionalization of CNF with PDA and ZnO-NPs. The high-resolution TEM and SEM analysis showed that ZnO-NPs have nanoneedle shapes and are homogeneously distributed onto the fibers with an average size of 3.92-8.77 nm, and the platforms have distinct mesoporous fibrous structures. The bionanoplatforms exhibited broad-spectrum antimicrobial activity against E. coli, Salmonella sp., S. aureus, L. monocytogenes, and C. albicans. Besides, the composite nanoplatform also demonstrated excellent cytocompatibility with normal human dermal fibroblasts (HFB-4), as reflected by their favorable IC₅₀ values. Furthermore, in scratch wound assays, the TCNF2 and BCNF2 scaffolds significantly promoted the healing, achieving wound confluences of 53.6 % and 52.7 %, respectively. These results suggest that the developed composites are promising candidates for wound healing applications.