Valence- and Phase-Engineered VP/WOx Heterojunction Microneedles for Photoresponsive Therapy of Infected Wounds

Bacterial infection and biofilm formation create a persistent wound microenvironment that requires effective antibacterial treatment while preserving tissue regeneration. However, current photoresponsive wound dressings often lack precise control over photothermal and ROS-mediated outputs, and their therapeutic function is usually diminished after degradation. To address this dilemma, we report novel valence-phase tunable violet phosphorene/tungsten oxide (VP/WO_x) heterojunctions integrated into poly(vinyl alcohol) microneedle patches for infected wound treatment. Twin heterojunctions, VP/WO_xα and VP/WO_xβ, were constructed with distinct interfacial structures, tungsten valence states, and electronic interactions. Under 808 nm irradiation, both heterojunctions showed efficient photoactivity and distinct therapeutic tendencies, with VP/WO_xα favoring photothermal conversion and VP/WO_xβ producing more ROS. Moreover, resulting microneedles retained strong antibacterial and antibiofilm activity against S. aureus and E. coli, and their degradation products further provided antibacterial effects. In a S. aureus-infected full-thickness wound model, NIR-activated P-VP/WO_xα strongly reduced bacterial burden and inflammation and promoted vascularized, collagen-rich tissue regeneration. This work highlights valence and phase engineering as an effective strategy for coordinating antibacterial therapy, degradability, and wound repair, thus providing a new approach for developing tunable photoresponsive platforms for infected wound healing.