Star-Chained Near-Infrared-Responsive Upconversion Nanoparticle/Fe-TCPP for Synergistic Photodynamic Therapy/Chemodynamic Therapy to Selectively Eradicate Staphylococcus aureus and Repair Infected Wounds.

In this study, a star-chained near-infrared responsive upconversion nanoparticle (UCNP)/Fe-TCPP nanocomposite (UFT) was fabricated via a two-step solvothermal method. Its phase, morphology, and structure were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FT-IR). Owing to electrostatic matching, UFT selectively targeted and killed Staphylococcus aureus. Under 980 nm irradiation at 1.0 W/cm2, 200 µg/mL UFT achieved a 98.46% bactericidal rate against 1 × 106 CFU/mL S. aureus within 18 min via a synergistic photodynamic/chemodynamic effect. In vivo wound healing experiments showed UFT promoted epidermal regeneration and accelerated wound repair. Radical trapping experiments coupled with electron spin resonance (ESR) spectroscopy identified superoxide anions (•O2-) and hydroxyl radicals (•OH) as the main reactive oxygen species involved in the process. These findings demonstrate that the as-prepared UFT nanocomposite exhibits both excellent near-infrared-responsive antibacterial performance and wound-healing efficacy, providing a promising experimental basis and theoretical foundation for the development of efficient photoresponsive antibacterial materials for the treatment of wounds infected with Gram-positive bacteria.