Platinum nanozymes system with tunable enzyme activity for on-demand supply therapy of infected wounds.

The rapid healing of bacterially infected wounds remains a major clinical challenge. The pathological microenvironment-characterized by bacterial infection, reactive oxygen species (ROS) accumulation, persistent inflammation, and impaired tissue repair-severely impedes this process. In this work, we constructed a photothermally triggered, microenvironmental pH-regulating platinum nanozyme system, ACC@LPDA_Pt nanoparticles (NPs), leveraging the pH-dependent peroxidase-like and catalase-like activities of platinum nanozymes. This system achieves enzyme-like activity conversion by modulating the wound pH, thereby accomplishing bactericidal effects, ROS scavenging, anti-inflammation, and promoting wound healing. Our study demonstrates that ACC@LPDA_Pt NPs exhibit a pronounced photothermal effect and the ability to modulate the microenvironmental pH. Moreover, their excellent hemocompatibility and cytocompatibility promote cell proliferation and migration. In the inflammatory microenvironment, ACC@LPDA_Pt achieved inhibition rates of 99.8 ± 0.1 % for Staphylococcus aureus (S. aureus) and 99.9 ± 0.1 % for Escherichia coli. Furthermore, the photothermal-induced dissolution of amorphous calcium carbonate (ACC) raises the microenvironmental pH to neutral, endowing ACC@LPDA_Pt with robust ROS scavenging and oxygen production capabilities. This process promotes wound healing by reducing inflammation, stimulating cell proliferation and migration, granulation tissue formation, collagen deposition, and neovascularization, thereby significantly accelerating the healing of S. aureus-infected wounds with a closure rate of 97.3 ± 1.2 %. These multifunctional properties make ACC@LPDA_Pt NPs a promising nano-therapeutic strategy for bacterial-infected wounds.