EGCG@ZIF-8@Polydopamine-Functionalized Janus Nanofibrous Dressing with Directional Exudate Transport and Photothermal Antibacterial Activity for Infected Wound Treatment

Abstract

The treatment of infected skin wounds continues to face multiple challenges, including bacterial resistance, persistent inflammation, oxidative damage, and inadequate exudate management. To address these issues, a multifunctional Janus wound dressing was constructed to achieve coordinated infection control and tissue repair. Zeolitic imidazolate framework-8 (ZIF-8) was used as a nanocarrier for the natural antioxidant molecule, and polydopamine surface coating endowed the composite nanoparticles with photothermal antibacterial activity. The composite nanoparticles were subsequently incorporated into a hydrophobic polycaprolactone layer by electrospinning and combined with a hydrophilic polyacrylonitrile layer containing a pH indicator, thereby forming a bilayer structure with unidirectional liquid transport, visual monitoring, and wound protection functions. The dressing promotes the outward transfer of wound exudate and produces an observable color response to changes in environmental pH. Under near-infrared irradiation, the antibacterial rate of the dressing reached 98.89% against E. coli and 99.99% against S. aureus. The dressing also possesses excellent free-radical-scavenging capacity, indicating its potential to alleviate excessive oxidative stress in infected wounds. Animal experiments further demonstrated that the dressing reduced the local infection burden, promoted wound closure, collagen deposition, and tissue formation, and caused no obvious histopathological abnormalities in major organs. Overall, this study presents a multifunctional Janus nanofibrous dressing that integrates antibacterial activity, antioxidant function, exudate regulation, and wound-status monitoring, providing a material-design approach for the repair of infected skin wounds.