Tailoring the Porosity of Mesoporous Polyphenol Nanoparticles for Enhanced Photothermal Antibacterial Therapy

Photothermal therapy offers a promising alternative for treating infected wounds while mitigating antibiotic overuse. However, the limited near-infrared (NIR) photothermal conversion efficiency of polymeric materials hinders their clinical translation. Herein, we report the synthesis of Mn-chelated mesoporous poly(L-DOPA) nanoparticles (Mn-mDOPA) via polymerization-induced self-assembly, where the surfactant/oil ratio and Mn loading are precisely tuned to optimize mesoporosity and photothermal performance. The resulting Mn-mDOPA nanoparticles exhibit enlarged mesopores (≈28-39 nm) and a high specific surface area (up to 75.4 m²·g^{- 1}), enabling superior light absorption and heat generation, as confirmed by COMSOL simulations demonstrating a surface-area-dependent photothermal conversion effect. These structural features endow Mn-mDOPA with efficient NIR-triggered bacterial eradication (99.9% for S. aureus and 99.7% for E. coli) and substantial dark antibacterial activity (> 90%), attributed to the synergistic effects of hyperthermia and mesopore-mediated bacterial disruption. Moreover, the abundant catechol groups impart potent ROS scavenging capacity, alleviating oxidative stress and protecting wound-related cells. In a S. aureus-infected wound model, Mn-mDOPA effectively suppresses inflammation, promotes angiogenesis, and accelerates wound closure. Collectively, these results highlight Mn-mDOPA as a multifunctional, antibiotic-free nanoplatform that integrates enhanced photothermal conversion, intrinsic antibacterial activity, and antioxidant protection, providing a highly promising strategy for localized infection control and wound regeneration.