Surface Oxygen Vacancies and Corona Polarization of Bi4Ti3O12 Nanosheets for Synergistically Enhanced Sonopiezoelectric Therapy

Sonopiezoelectric therapy, an ultrasound-activated piezoelectric nanomaterial for tumor treatment, has emerged as a novel alternative modality. However, the limited piezoelectric catalytic efficiency is a serious bottleneck for its practical application. Excellent piezoelectric catalysts with high piezoelectric coefficients, good deformability, large mechanical impact surface area, and abundant catalytically active sites still need to be developed urgently. In this study, the classical ferroelectric material, bismuth titanate (Bi4Ti3O12, BTO), is selected as a sonopiezoelectric sensitizer for tumor therapy. BTO generates electron–hole pairs under ultrasonic irradiation, which can react with the substrates in a sonocatalytic-driven redox reaction. Aiming to further improve the catalytic activity of BTO, modification of surface oxygen vacancies and treatment of corona polarization are envisioned in this study. Notably, modification of the surface oxygen vacancies reduces its bandgap and inhibits electron–hole recombination. Additionally, the corona polarization treatment immobilized the built-in electric field on BTO, further promoting the separation of electrons and holes. Consequently, these modifications greatly improve the sonocatalytic efficiency for in situ generation of cytotoxic ROS and CO, effectively eradicating the tumor.