On-Demand Switching of a pH/ROS-Responsive Ce Single-Atom Nanozyme Spray for Infected Wounds

The healing of infected wounds is often hampered by a dynamically evolving pathological microenvironment. Conventional static therapeutic approaches lack the adaptability to address these changes. Herein, a pH/reactive oxygen species (ROS) dual-responsive cerium single-atom nanozyme spray was developed, intelligently adapting to the dynamic microenvironment of infected wounds. In the initial infection, it responds to an acidic microenvironment and exerts potent antibacterial activity by exhibiting cascade glucose oxidase (GOD)- and peroxidase (POD)-like activities to generate abundant ROS. As the infection is controlled and the pH neutralizes, the nanozyme switches to mimic superoxide dismutase (SOD)- and catalase (CAT)-like activities, scavenging excess ROS and revering the pro-inflammatory immune microenvironment. This "on-demand switching" capability enables microenvironment-dependent adaptive therapeutic strategies for antibacterial and anti-inflammatory effects, facilitating transitions seamlessly throughout the treatment process and offering a novel solution for dynamic wound healing.