A visible-light-switchable bidirectional nanozyme spray dressing for diagnosis, sterilization, and regeneration of infected wounds

Integrates ZIF-8/H-MPB heterostructures into smart polysaccharide sprayable matrices • Engineers metabolic redox-responsive Prussian blue reduction for visual monitoring • Drives augmented photon harvesting via heterojunctions for synergistic ROS bursts • Switches nanozyme activity autonomously after light-off to resolve oxidative stress • Couples matrix degradation with synchronized Zn 2+ release to guide tissue repair Chronic infected wounds remain a clinical challenge due to a vicious cycle of bacterial load, persistent inflammation, and oxidative stress that hinders tissue regeneration. Herein, we report BC-CS@ZHP, a theranostic sprayable composite wound interface material designed for this spatiotemporally dynamic pathology. The material comprises an oxidized bacterial cellulose/chitosan matrix and a visible-light-switchable bidirectional nanozyme (ZHP) core, enabling conformal in situ film formation on irregular wounds. ZHP, consisting of ZIF-8 and hollow mesoporous Prussian blue (H-MPB). Under simulated visible light, ZHP generates antimicrobial reactive oxygen species (ROS) via ZIF-8 mediation. Upon turning off the light, the H-MPB core acts as an ROS-scavenging nanozyme, relieving oxidative stress and polarizing macrophages toward a reparative phenotype. Concurrently, sustained Zn 2+ release promotes fibroblast migration, angiogenesis, and extracellular matrix (ECM) remodeling. Furthermore, as Prussian blue (PB) electronically reduce to Prussian white (PW), the material provides visual colorimetric monitoring of bacterial load, guiding dressing replacement. In a Staphylococcus aureus ( S. aureus )-infected wound model, BC-CS@ZHP efficiently controlled infection, normalized the immune microenvironment, and accelerated vascularized tissue regeneration with negligible systemic toxicity. This study establishes a diagnosis-clearance-reprogramming-regeneration strategy for infected wound management, providing a versatile guideline for designing stage-adaptive biomaterials. A visible-light-Switchable bidirectional nanozyme (ZHP) embedded in a sprayable TO-BC/chitosan film enables an “antibacterial-to-regenerative” cascade: light-on generates ROS to kill bacteria, while light-off scavenges ROS, polarizes macrophages to M2, and releases Zn 2+ to promote angiogenesis, accelerating infected wound healing. Download: Download high-res image (382KB) Download: Download full-size image