Toxic effects of SiO 2 NPs in early embryogenesis of Xenopuslaevis.

The exposure of organisms to the nanoparticulate is potentially hazardous, particularly when it occurs during embryogenesis. The effects of commercial SiONPs in early development were studied, using Xenopus laevis as a model to investigate their possible future employment by means of the Frog Embryo Teratogenesis Assay-Xenopus test (FETAX). The SiONPs did not change the survival but produced several abnormalities in developing embryos, in particular, the dorsal pigmentation, the cartilages of the head and branchial arches were modified; the encephalon, spinal cord and nerves are anomalous and the intestinal brush border show signs of suffering; these embryos are also bradycardic. In addition, the expression of genes involved in the early pathways of embryo development was modified. Treated embryos showed an increase of reactive oxygen species. This study suggests that SiONPs are toxic but non-lethal and showed potential teratogenic effects in Xenopus. The latter may be due to their cellular accumulation and/or to the effect caused by the interaction of SiONPs with cytoplasmic and/or nuclear components. ROS production could contribute to the observed effects. In conclusion, the data indicates that the use of SiONPs requires close attention and further studies to better clarify their activity in animals, including humans.