Induction of cell death by Ta3N5 in the human cancer cell line

Photocatalysts are widely used in modern society, and their applications extend to medicine. Until now, ultraviolet light irradiation has been required for photocatalysis, but tantalum nitride (Ta3N5) has attracted attention as a next-generation photocatalyst because it produces reactive oxygen species (ROS) upon visible light irradiation. However, it has never been used in life science, and its toxicity was unknown. In the present study, we evaluated the cytotoxicity of Ta3N5 using U2OS cells in terms of light dose, irradiation time, Ta3N5 dope, and light wavelength. We also investigated the mode and mechanism of induced cell death. The results showed that cytotoxicity increased in a dose-, time-, and Ta3N5 dope-dependent manner, especially with blue light irradiation. On the other hand, high-dose light irradiation induced cytotoxicity with or without Ta3N5, indicating that green light and red light irradiation, which can selectively toxicize Ta3N5-added cells, may also be effective. We also showed that Ta3N5 induces secondary necrotic cell death in U2OS cells. These data indicate that Ta3N5 may be a photocatalyst that can be used in the medical and life science fields.