NIR-II-Activated iridium single-atom nanozymes for synergistic antibacterial therapy and tissue regeneration in MRSA-infected wounds and acute lung injury

Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) remains a major pathogen in ventilator-associated pneumonia and wound infections. To address the limitations of traditional antibiotics, we developed a novel iridium-based single-atom catalyst (Ir/CN SAC) anchored on a nitrogen-doped carbon matrix. Engineered for ultra-low metal loading and maximal active site exposure, this catalyst integrates robust photothermal and catalytic functionalities. Under second near-infrared (NIR-II, 1270 nm) irradiation, the Ir/CN SAC efficiently converts light to heat and catalytically generates reactive oxygen species (ROS), achieving a potent photothermal-catalytic synergistic effect. This dual-action mechanism enabled rapid bacterial eradication <i>in vitro</i> and significantly accelerated wound healing and lung tissue repair in MRSA-infected <i>in vivo</i> models. Transcriptomic analyses revealed downregulation of pro-inflammatory pathways, shedding light on the immunomodulatory roles of the treatment. Notably, the Ir/CN SAC exhibited negligible toxicity and enhanced peroxidase-mimicking activity via thermal activation. Collectively, the Ir/CN SAC presents a promising strategy for treating MRSA infections in wounds and the lungs via a synergistic treatment model.