Sonocatalytic injury of cancer cells attached on the surface of a nickel–titanium dioxide alloy plate

•Nickel–titanium dioxide alloy plate was used as sonocatalyst and culture surface.•Nickel–titanium alloy plate was used as a non-sonocatalytic control.•Ultrasound irradiation of nickel–titanium dioxide alloy plate generated hydroxyl radical.•Ultrasound irradiation injured cancer cells on nickel–titanium dioxide alloy plate.•Ultrasound irradiation of cancer cells on Ni–TiO2 alloy plate led to apoptosis.

The present study demonstrates ultrasound-induced cell injury using a nickel–titanium dioxide (Ni–TiO2) alloy plate as a sonocatalyst and a cell culture surface. Ultrasound irradiation of cell-free Ni–TiO2 alloy plates with 1 MHz ultrasound at 0.5 W/cm2 for 30 s led to an increased generation of hydroxyl (OH) radicals compared to nickel–titanium (Ni–Ti) control alloy plates with and without ultrasound irradiation. When human breast cancer cells (MCF-7 cells) cultured on the Ni–TiO2 alloy plates were irradiated with 1 MHz ultrasound at 0.5 W/cm2 for 30 s and then incubated for 48 h, cell density on the alloy plate was reduced to approximately 50% of the controls on the Ni–Ti alloy plates with and without ultrasound irradiation. These results indicate the injury of MCF-7 cells following sonocatalytic OH radical generation by Ni–TiO2. Further experiments demonstrated cell shrinkage and chromatin condensation after ultrasound irradiation of MCF-7 cells attached on the Ni–TiO2 alloy plates, indicating induction of apoptosis.