Defect-Boosted Piezoelectric and Nanozymatic Synergetic Catalysis for Deep Bacterial Abscess Therapy

Piezocatalytic therapy, distinguished by its superior tissue penetration under ultrasound activation and its low dependence on the oxygen concentration for generating multiple reactive oxygen species (ROS), has emerged as a promising strategy for deep abscess treatment. However, its efficacy remains constrained by a suboptimal bandgap, weak piezoelectric responses, and inadequate surface-active sites. To address these limitations, a facile Ru-atom doping strategy is first proposed using the Bi₄O₅Br₂-based nanosystem (Bi₄O₅Br₂@Ru) to tailor the bandgap and boost the piezo- and enzyme-like catalysis. The Ru dopants induce lattice distortions and elevate oxygen vacancies simultaneously, thereby enhancing piezoelectric responses while conferring peroxidase (POD)- and catalase (CAT)-like enzymatic activities. Under ultrasound excitation, the piezoelectric field optimizes the conduction band alignment of Bi₄O₅Br₂@Ru, enhancing its POD-like activity to generate multiple ROS including ·OH, ¹O₂, and ·O₂^-. The mixed Ru (III/IV) valence states in Bi₄O₅Br₂@Ru induce glutathione depletion, thereby further enhancing the oxidative stress capacity to combat biofilms. The enhanced CAT-like activity further alleviates hypoxia within biofilm microenvironments. RNA transcriptomic analysis confirms that Bi₄O₅Br₂@Ru disrupts energy metabolism by interfering with the tricarboxylic acid cycle. The dual-modality therapy leverages doping engineering to seamlessly combine piezoelectric properties with enzyme-like catalytic functions, offering a highly promising therapeutic strategy for the treatment of deep-seated infectious diseases.