Harnessing Defect Engineered Multiferroic Catalysts for Cascade Responsive Microwave and Sonodynamic Therapy in Osteomyelitis

ABSTRACT Efficient multi physics energy conversion, particularly the transformation of microwave and ultrasound energy into localized heat and reactive oxygen species, offers great potential for non‐invasive biomedical therapy. However, conventional single modal catalysts suffer from inefficient energy coupling and rapid charge recombination. Here, we develop a defect engineered multi field responsive catalytic platform by integrating manganese doped bismuth ferrite nanocatalysts with Rehmannia Polygonati derived extracellular vesicles in an injectable hydrogel. Density functional theory calculations reveal that Mn doping induces defect dipoles to regulate the electronic structure of bismuth ferrite, suppress leakage currents, and enhance dielectric loss and piezoelectric responses. This enables sequential thermo piezocatalytic energy conversion, where microwave irradiation generates localized heating to reduce catalytic barriers and subsequent ultrasound stimulation promotes piezoelectric charge separation for efficient reactive oxygen species production. The synergistic catalytic process effectively eradicates deep seated biofilms in chronic osteomyelitis. Meanwhile, hydrogel degradation releases extracellular vesicles to regulate macrophage polarization and promote bone regeneration. This work establishes a defect engineered multi physics energy conversion platform for efficient microwave and ultrasound driven heat and reactive oxygen species generation, providing a promising strategy for complex deep tissue infection treatment.