Toxicity of nanotitanium dioxide (TiO 2 -NP) on human monocytes and their mitochondria.

The effect of nanotitanium dioxide (TiO2 -NP) in human monocytes is still unknown. Therefore, an understanding of probable cytotoxicity of TiO2 -NP on human monocytes and underlining the mechanisms involved is of significant interest. The aim of this study was to assess the cytotoxicity of TiO2 -NP on human monocytes. Using biochemical and flow cytometry assessments, we demonstrated that addition of TiO2 -NP at 10 μg/ml concentration to monocytes induced cytotoxicity following 12 h. The TiO2 -NP-induced cytotoxicity on monocytes was associated with intracellular reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, TiO2 -NP triggers oxidative stress and organelles damages in monocytes which are important cells in defense against foreign agents. Finally, our findings suggest that use of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with TiO2 -NP.