pH Switchable Nanozyme Platform for Healing Skin Tumor Wound Infected with Drug-Resistant Bacteria

Nanozymes capable of generating reactive oxygen species have recently emerged as promising treatments for wounds infected with drug-resistant bacteria, possessing a reduced possibility of inducing resistance. However, the therapeutic effect is limited by a shortage of endogenous oxy-substrates and undesirable off-target biotoxicity. Herein, a ferrocenyl coordination polymer (FeCP) nanozyme, featuring pH switchable peroxidase (POD)- and catalase (CAT)-like activity is incorporated with indocyanine green (ICG) and calcium peroxide (CaO₂ ) to fabricate an H₂ O₂ /O₂ self-supplying system (FeCP/ICG@CaO₂ ) for precise treatment of bacterial infections. At the wound site, CaO₂ reacts with water to generate H₂ O₂ and O₂ . Acting as a POD mimic under an acidic bacterial microenvironment, FeCP catalyzes H₂ O₂ into hydroxyl radicals to prevent infection. However, FeCP switches to CAT-like activity in neutral tissue, decomposing H₂ O₂ into H₂ O and O₂ to prevent oxidative damage and facilitate wound healing. Additionally, FeCP/ICG@CaO₂ shows photothermal therapy capability, as ICG can emit heat under near-infrared laser irradiation. This heat assists FeCP in fully exerting its enzyme-like activity. Thus, this system achieves an antibacterial efficiency of 99.8% in vitro for drug-resistant bacteria, and effectively overcomes the main limitations of nanozyme-based treatment assays, resulting in satisfactory therapeutic effects in repairing normal and special skin tumor wounds infected with drug-resistant bacteria.