Carboxymethyl bacterial cellulose electrospun nanofibers loaded with zinc oxide nanoparticles and polyhexamethylene biguanide for wound healing promotion

This study explores the development of a novel wound dressing incorporating bacterial cellulose (BC) produced by <i>Acetobacter xylinum</i>, which was carboxymethylated to enhance its biomedical applicability. Zinc oxide nanoparticles (ZnONPs) were biosynthesized using a green method with <i>Quercus infectoria</i> gall extracts (QIG). The composite dressing, composed of BC and polyurethane (PU) nanofibers, was further functionalized with ZnONPs and polyhexamethylene biguanide (PHMB) to provide enhanced antibacterial and wound healing properties. The PU/BC/ZnONPs/PHMB nanofiber mat exhibited strong antibacterial activity against Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), with inhibition zones of 28 and 29 mm for PU/BC/ZnONPs and PU/BC/ZnONPs/PHMB, respectively, surpassing the 12 mm inhibition zone of the Cefoxitin control. The nanofibers had an optimal mean diameter of 71.12 nm, ensuring a high surface area for cell attachment. Mechanical tests confirmed excellent tensile strength and flexibility, while an optimized water vapor transmission rate (∼2000-3000 g/m²/day) facilitated a moist wound environment for enhanced healing. L929 fibroblast studies demonstrated high cell viability (∼95-98%) and enhanced migration, confirming the nanofiber mat's biocompatibility. <i>In vivo</i> wound healing tests showed that PU/BC/ZnONPs/PHMB significantly accelerated wound closure, achieving 90-100% healing by day 10, outperforming PU and PU/BC groups. Bacterial counts were significantly reduced, with complete bacterial inhibition observed by day 5. In conclusion, the PU/BC/ZnONPs/PHMB nanofiber dressing demonstrated superior antibacterial activity, mechanical strength, moisture regulation, and wound healing potential, making it a promising candidate for advanced clinical wound management.