• A magnetic vortex Fe 3 O 4 @TiO 2 @Pt nanostructure is developed for sequentially activated antibacterial therapy. • Magnetothermal priming facilitates cavitation and boosts Pt assisted TiO 2 catalysis under ultrasound. • The treatment enables broad spectrum antibacterial activity, biofilm disruption, and image guided therapy in infection models. Polymicrobial infections and antibiotic-resistant strains often persist within biofilms, where undermine conventional chemotherapies. Here we introduce a sequentially activated antibacterial platform built on magnetic-vortex Fe 3 O 4 nanorings coated with TiO 2 and decorated with Pt nanoparticles. This alternating magnetic field (AMF) then ultrasound (US) sequence is designed to reactive oxygen species (ROS) amplification. AMF produces rapid, localized heating that swells biofilm, and increases bacterial envelope permeability. Subsequent US triggers TiO 2 sonocatalysis through cavitation and sonoluminescence, generating electron-hole pairs; the Pt-TiO 2 Schottky junction selectively traps electrons and suppresses recombination, extending carrier lifetimes and boosting interfacial reaction probability. In parallel, Pt exhibits nanozyme activity that converts endogenous H 2 O 2 into short-lived reactive intermediates, amplifying ROS flux. In vitro , against four bacteria, the platform suppresses planktonic growth and disrupts biofilms with efficient membrane damage. In vivo , in subcutaneous and pulmonary infection models, the AMF → US regimen decreases bacterial burden and accelerates tissue restoration, outperforming multiple comparators while maintaining good biocompatibility and procedural safety. This magnetothermal preheating followed by sonocatalytic amplification establishes an antibiotic-free, imageable paradigm that couple’s biofilm disruption with potent bactericidal action, offering a generalizable engineering route for complex, polymicrobial, and resistance-associated infections.
Zhao et al. (Sun,) studied this question.