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

Titanium dioxide (TiO) 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 NRs and TiO NRs loaded with Ag or Au NPs on boar spermatozoa. As a result, sperm incubated with Ag-TiO NRs showed lower motility than sperm incubated with controls (with or without TiO NRs) or Au-TiO NRs. In addition, sperm viability and acrosomal integrity were defective in the presence of Ag-TiO NRs, and the generation of intracellular reactive oxygen species (ROS) increased significantly when spermatozoa were incubated with 20 μg/ml Ag-TiO NRs. We discussed in depth the charge transfer mechanism between enzymatic NADPH and Ag-TiO NRs in the context of ROS generation in spermatozoa. The effects we observed reflected the fertilization competence of sperm incubated with Ag-TiO NRs; specifically sperm penetration and embryonic development rates by in vitro fertilization were reduced by Ag-TiO NRs. To summarize, our findings indicate that exposure to Ag-TiO NRs could affect male fertilization fecundity and caution that care be exercised when using these NRs.