Zirconia Nanoparticles-Induced Toxic Effects in Osteoblast-Like 3T3-E1 Cells

Zirconia (ZrO₂) is one of the widely used metal oxides for potential bio-applications such as biosensors, cancer therapy, implants, and dentistry due to its high mechanical strength and less toxicity. Because of their widespread applications, the potential exposure to these nanoparticles (NPs) has increased, which has attracted extensive attention. Thus, it is urgent to investigate the toxicological profile of ZrO₂ NPs. Titanium dioxide (TiO₂) is another extensively used nanomaterials which are known to be weakly toxic. In this study, TiO₂ NPs were served as control to evaluate the biocompatibility of ZrO₂ NPs. We detected the cytotoxicity of TiO₂ and ZrO₂ NPs in osteoblast-like 3T3-E1 cells and found that reactive oxygen species (ROS) played a crucial role in the TiO₂ and ZrO₂ NP-induced cytotoxicity with concentration-dependent manner. We also showed TiO₂ and ZrO₂ NPs could induce apoptosis and morphology changes after culturing with 3T3-E1 cells at high concentrations. Moreover, TiO₂ and ZrO₂ NPs at high concentrations could inhibit cell osteogenic differentiation, compared to those at low concentrations. In conclusion, TiO₂ and ZrO₂ NPs could induce cytotoxic responses in vitro in a concentration-dependent manner, which may also affect osteogenesis; ZrO₂ NPs showed more potent toxic effects than TiO₂ NPs.