Bidirectional redox-modulating vanadium carbide-integrated smart microneedles for infected wound healing

Wound healing is plagued by an inherent reactive oxygen species (ROS) paradox: elevated ROS are critical for antibacterial defense, yet excessive ROS levels impede inflammation resolution and tissue repair. Conventional single-component nanomaterials lack the capacity for bidirectional ROS regulation, while multi-drug combination strategies suffer from complex regulatory modalities, poor stability, and antimicrobial resistance issues-all of which limit clinical translation. To address these challenges, we develop a vanadium carbide (V₄C₃)-iodinene (Ine)@polyvinyl alcohol (PVA) smart microneedle system. Notably, V₄C₃ within the system exhibits intrinsic bifunctionality: it not only generates ROS under light irradiation to enable photodynamic antibacterial therapy but also scavenges excess ROS after irradiation. Further enhanced by Ine and PVA microneedles, which boost functional adaptability and biocompatibility, this system forms a therapeutic platform with excellent mechanical strength, adaptive wound conformity, and laser-controlled switchable ROS regulation. In vitro and in vivo experiments demonstrate its potent antibacterial activity, its ability to induce M2 macrophage polarization, and its ability to reduce pro-inflammatory cytokine expression, thereby alleviating inflammation and accelerating wound healing. By leveraging V₄C₃'s bifunctionality and combining it with microneedle delivery and laser regulation, the simplified yet intelligent wound-healing platform resolves the ROS paradox, avoids issues such as drug resistance, and holds great potential for clinical translation.