Titanium Dioxide Nanoparticles Interaction, Uptake and Genotoxicity in Salmonella typhimurium Bacteria

摘要

Titanium dioxide (TiO_2) nanoparticles (NPs) were characterized using dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), zeta potential analysis and transmission electron microscopy (TEM) with corresponding energy dispersive X-ray spectroscopy (EDS). Genotoxicity experiments with Salmonella strains TA98 and TA100 were negative when performed using a miniaturized pre-incubation assay. Flow cytometry experiments indicated a time and dose-dependent interaction of the NPs with the bacteria. Subsequent TEM analysis revealed that although the NPs heavily associated with the bacterial cell wall, only trace amounts could be found within the bacterium. This result suggested limited to no uptake of the NPs by the bacteria. The lack of uptake of NPs was consistent with the negative results found in the bacterial mutagenicity assays. The results suggest that alternative assays, e.g. mammalian cell-based assays, may be more appropriate for the assessment of the genotoxicity of nanomaterials, in particular TiO_2 NPs.