Toxicity and genotoxicity of organic and inorganic nanoparticles to the bacteria Vibrio fischeri and Salmonella typhimurium.

The present work aimed at evaluating the toxicity and genotoxicity of two organic (vesicles composed of sodium dodecyl sulphate/didodecyl dimethylammonium bromide-SDS/DDAB and of monoolein and sodium oelate-Mo/NaO) and four inorganic (titanium oxide-TiO₂, silicon titanium-TiSiO₄, Lumidot-CdSe/ZnS, and gold nanorods) nanoparticles (NP), suspended in two aqueous media (Milli Q water and American Society for Testing and Materials (ASTM) hardwater), to the bacteria Vibrio fischeri (Microtox test) and Salmonella typhimurium-his⁻ (Ames test with strains TA98 and TA100). Aiming a better understanding of these biological responses physical and chemical characterization of the studied NP suspensions was carried out. Results denoted a high aggregation state of the NP in the aqueous suspensions, with the exception of SDS/DDAB and Mo/NaO vesicles, and of nanogold suspended in Milli Q water. This higher aggregation was consistent with the low values of zeta potential, revealing the instability of the suspensions. Regarding toxicity data, except for nano TiO₂, the tested NP significantly inhibited bioluminescence of V. fischeri. Genotoxic effects were only induced by SDS/DDAB and TiO₂ for the strain TA98. A wide range of toxicity responses was observed for the six tested NP, differing by more than 5 orders of magnitude, and suggesting different modes of action of the tested NP.