Development of Self-Oxygenated Nano-MnO2 Composites for Enhanced Antibacterial Photodynamic Therapy

The rise of antibiotic resistance and the slow pace of new antibiotic discovery highlight the urgent need for alternative antimicrobial strategies. Antimicrobial photodynamic therapy (aPDT) is a promising candidate, but its efficacy is limited by shallow light penetration and hypoxic microenvironments in deep-seated infections such as abscesses and biofilms. Here, we developed a self-oxygenating nanocomposite (HTCC-MnO 2 -Ce6, HMC) to overcome these barriers. Quaternized chitosan (HTCC) provided intrinsic antibacterial activity and facilitated electrostatic interactions with bacterial membranes. MnO 2 nanoparticles catalyzed endogenous hydrogen peroxide (H 2 O 2 ) into O 2 , thereby alleviating hypoxia and sustaining reactive oxygen species (ROS) generation under light irradiation. Ce6 acted as a photosensitizer to induce oxidative damage, while the HTCC matrix further promoted bacterial membrane disruption. In vitro , HMC displayed excellent cytocompatibility and achieved over 95% bacterial reduction under hypoxic conditions. In a methicillin-resistant Staphylococcus aureus ( MRSA ) abscess model, treatment markedly decreased bacterial burden, attenuated inflammation, and accelerated wound closure within 14 days. Collectively, this self-oxygenating nanoplatform integrates catalytic oxygen generation, membrane-targeted antibacterial activity, and photodynamic therapy, offering a potent non-antibiotic approach for managing multidrug-resistant infections and promoting abscess healing.