Engineering copper nanoparticle/polysaccharide-immobilized cotton gauze for accelerated healing of Staphylococcus aureus-infected dermal wounds

Abstract

Bacterial infection remains a major challenge in wound management, often leading to delayed healing, prolonged treatment, and increased healthcare costs. Antimicrobial dressings provide an effective approach to prevent and control wound infections, thereby supporting faster wound repair. Although many antimicrobial dressings are commercially available and widely studied, most are either loaded with antibiotics, which raises concerns about antibiotic resistance, or contain silver nanoparticles (Ag NPs), which increase the overall cost. Therefore, this work presents a cost-efficient strategy for developing a highly effective antimicrobial wound dressing by functionalizing medical-grade cotton gauze (CG) with two polysaccharides, N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and dextran, followed by in situ immobilization of copper nanoparticles (Cu NPs). To establish a structure–activity relationship, the immobilized Cu NPs were systematically characterized using SEM, EDX, XPS, and AAS to evaluate the influence of particle size, Cu loading, and release behaviour on antibacterial performance. The modified gauze demonstrated excellent antibacterial activity, where the lowest Cu-loaded sample with smaller nanoparticles achieved a ∼4-log reduction in S. aureus, while the highest Cu-loaded gauze (average size ∼700 nm) achieved >5-log reduction. In addition, the dressing demonstrated sustained Cu release and high cytocompatibility, and supported cell migration in vitro. Importantly, in vivo studies using the S. aureus-infected rat wound model revealed that the modified CG dressing outperformed a commercial anti-infective dressing by significantly reducing bacterial load, accelerating tissue regeneration, and suppressing inflammation. Overall, this study provides important insights into Cu NP-functionalized CG and highlights its potential as an effective and affordable antimicrobial dressing for the management of infected wounds.