“…Barium titanate, as a typical piezoelectric material, has attracted extensive attention due to its excellent piezoelectric, dielectric, and ferroelectric properties and wonderful biocompatibility since its appearance. 26,27 Herein, piezoelectric barium titanate nanoparticles (BTNPs) were selected as research objects to investigate the effects of BTNPs with different crystal phases and piezoelectric properties (i.e., BTO, U-BTO, P-BTO) on the activity of BC cells with or without external ultrasound stimulation (US). In this study, cubic barium titanate (BTO), tetragonal unpolarized barium titanate (U-BTO), and tetragonal polarized barium titanate (P-BTO) shared the same morphology and particle size but were different in the intensities of internal ES generated under exogenous mechanical stimulation, with the ES intensities of BTO, U-BTO, and P-BTO being 0 mV, 425 mV, and 886 mV, respectively.…”