NIR-Triggered Janus Nanofiber Dressing with Synergistic Photodynamic Antibacterial Action and Sustained Oxygen Release for Accelerated Healing of Infected Wounds.

Abstract

Impaired wound healing poses life-threatening risks due to uncontrolled multidrug-resistant bacterial infections. Although photodynamic therapy (PDT) represents a promising non-antibiotic strategy to combat antibiotic-resistant pathogens, its efficacy in wound dressings faces two fundamental limitations: inadequate light penetration depth hindering photosensitizer activation and hypoxia suppressing reactive oxygen species generation. To address these limitations, a near-infrared (NIR)-activated multifunctional bilayer Janus nanofibrous dressing featuring asymmetric hydrophobicity/hydrophilicity is engineered. This bilayer architecture integrates three synergistic functions: i) A hydrophilic CaO₂-doped inner layer enabling quick blood absorption and oxygen release, promoting cell proliferation and tissue regeneration. ii) A hydrophobic outer layer with embedded NaYF₄:Yb,Er@mSiO₂@Ce6 achieving NIR-triggered singlet oxygen (¹O₂) to eradicate bacteria. iii) Continuous oxygen supply from the hydrophilic layer, sustaining the photosensitization for the PDT process and thus overcoming the hypoxic-induced limitations. In vitro and in vivo studies demonstrate the designed Janus nanofibrous dressing's excellent biocompatibility, rapid hemostasis, and near-complete bacterial eradication (>99.99%). By synchronizing hemostasis, oxygenation, and hypoxia-alleviated PDT, this platform significantly accelerates the healing of infected wounds through sequential hemostasis-proliferation-remodeling phases within 12 days, achieving near-complete recovery compared to only 47.6% in the control group. This work provides a promising strategy for designing new dressings for infected wounds.