Interfacial construction and wound-healing mechanisms of polyphenol–metal/polymer Janus films with unidirectional fluid transport and synergistic antimicrobial activity

Wound healing is a dynamic, tightly orchestrated cascade that is readily disrupted by excessive exudate, bacterial infection, and persistent oxidative stress. Conventional dressings remain constrained by poor biocompatibility, inadequate exudate management, and isolated, single functions, and consequently fail to satisfy the demands of complex wound repair. Here, an asymmetric Janus nanofibrous membrane (PGPT/PM) is developed via sequential electrospinning, featuring the deliberate spatial compartmentalization of supramolecular poly-L-lysine–tannic acid (PLL–TA) complexes and coordination-driven TA-Sr²⁺ nanoparticles. Confining PLL–TA within the inner polycaprolactone/gelatin layer resolves tannic acid phase separation in spinning dopes and accelerates hydration (0.8 s), mounting immediate broad-spectrum bactericidal activity (>94% against S. aureus and E. coli) and intracellular reactive oxygen species (ROS) quenching at the wound interface. Meanwhile, anchoring TA-Sr²⁺ nanoparticles in the outer hydrophobic PCL layer maintains a sharp wettability disparity that autonomously pumps excess exudate outward within 40 s while enforcing steady, prolonged Sr²⁺ release to stimulate endothelial migration. In a full-thickness infected wound model, the dressing reached a healing rate of 94.30 ± 1.73% by day 9 and achieved complete re-epithelialization by day 11. This strategy of pairing directional fluid pumping with spatiotemporally orchestrated non-antibiotic bioactivities offers a robust platform for managing complex infected wounds. A multifunctional Janus wound dressing was fabricated by electrospinning layer-by-layer assembly. Tannic acid-Sr²⁺ nanoparticles were introduced into the hydrophobic layer, and poly-L-lysine‒polyphenol complexes were introduced into the hydrophilic layer while retaining the inherent hydrophilic and hydrophobic properties of the materials. The prepared Janus film integrates unidirectional liquid transport and antibacterial, antioxidant and pro-angiogenic functions. This study provides a targeted solution for wound healing and demonstrates great application potential in wound dressings. Download: Download high-res image (203KB) Download: Download full-size image