Inactivation of mammalian spermatozoa on the exposure of TiO 2 nanorods deposited with noble metals.

Titanium dioxide (TiO 2 ) nanorods (NRs) are well-known semiconducting and catalytic material that has been widely applied, but their toxicities have also attracted recent interest. In this study, we investigated and compared the toxic effects of TiO 2 NRs and TiO 2 NRs loaded with Ag or Au NPs on boar spermatozoa. As a result, sperm incubated with Ag-TiO 2 NRs showed lower motility than sperm incubated with controls (with or without TiO 2 NRs) or Au-TiO 2 NRs. In addition, sperm viability and acrosomal integrity were defective in the presence of Ag-TiO 2 NRs, and the generation of intracellular reactive oxygen species (ROS) increased significantly when spermatozoa were incubated with 20 μg/ml Ag-TiO 2 NRs. We discussed in depth the charge transfer mechanism between enzymatic NADPH and Ag-TiO 2 NRs in the context of ROS generation in spermatozoa. The effects we observed reflected the fertilization competence of sperm incubated with Ag-TiO 2 NRs; specifically sperm penetration and embryonic development rates by in vitro fertilization were reduced by Ag-TiO 2 NRs. To summarize, our findings indicate that exposure to Ag-TiO 2 NRs could affect male fertilization fecundity and caution that care be exercised when using these NRs.