Environmental Charge-Mediated Nanopiezocatalysis for Sonodynamic Therapy.

Piezocatalysis garners growing attention in sonodynamic therapy (SDT). However, its mechanism remains controversial due to the prominent but conflicting theories of energy band and piezoelectric effect. The former just focuses on the role of carriers, while the latter emphasizes only the contribution of screening charges. This divergence greatly hinders the development of piezocatalysis-mediated SDT. Here, we demonstrate the combined action of carriers (electrons/holes) and screening charges on piezocatalysis and propose a new piezocatalytic model (termed environmental charge-mediated nanopiezocatalysis) based on defective BaTiO3@TiO2 piezoelectric nanoparticles (D-B@T). The synergistic effect of carriers and screening charges endows D-B@T with superior reactive oxygen species generation capability under ultrasound stimulation and enables effective SDT treatment of bacterial pneumonia in vivo. This work offers an insightful understanding of piezocatalysis and guides the rational design of high-performance piezoelectric nanosonosensitizers for SDT.