Infection-responsive theragnostic microneedle patches for real-time monitoring and deep biofilm eradication

Deep wound infections remain difficult to treat because bacteria infiltrate poorly vascularized tissues and establish biofilms that severely restrict antimicrobial penetration and therapeutic efficacy. Here, we engineer a hierarchically structured dual-layer dissolvable microneedle that integrates ultrasmall silver nanoclusters (AgNCs) with spatiotemporally programmed therapeutic functions, enabling rapid infection indication, sustained antimicrobial delivery, and microenvironment modulation for the treatment of deep biofilm-associated wound infections. The outer layer generates an immediate colorimetric indication of bacterial infection and initiates rapid Ag + release based on pH changes, whereas the inner layer delivers prolonged antimicrobial and antioxidant therapy over 24 h. In vitro studies demonstrated potent antibiofilm activity, achieving 6-log reduction in viable pathogens, accompanied by significant reductions in biofilm biomass, integrity and thickness. Beyond antimicrobial activity, the microneedle promoted wound repair through reactive oxygen species (ROS) scavenging and demonstrated excellent cytocompatibility, supporting faster wound closure within 12 h. In vivo evaluation using an infected burn wound model demonstrated effective elimination of S. aureus biofilm infection and accelerated wound healing over 12 days. Collectively, these findings demonstrate that the AgNC-loaded MNs provide sustained localized antimicrobial activity, effective biofilm eradication, and oxidative stress modulation, representing a promising strategy for treating deep biofilm-associated chronic wound infections.