Effect of maternal exposure to silica nanoparticles

The importance of nanotechnology is widely recognized in both biomedical and industrial applications, so the search for new nano materials with improved physical and chemical characteristics is rapidly growing, causing a consequent increase in the risk of exposure by the population.Engineered nanoparticles, defined as particles having a different shape, but at least one dimension less than 100 nm, are constituents of many everyday products, including for example, sunscreens, cosmetics and some food packaging. This implies that an increasing number of people can come into contact with these nanoparticles in occupational settings, and the environment. It then becomes mandatory to assess what potential effects nanoparticles may have on biological systems. Although many nanoparticles may not be a problem for the general population, may instead be a problem for subgroups of susceptible individuals. In this context, we aimed to study the effect that maternal exposure to silica nanoparticles (SiO2 NPs) may have on the health of pregnant individuals, with particular attention to the possible harmful effects on the development of the placenta and fetus. To this end we have produced silica nanoparticles of three different sizes: small, medium and large. Each nanoparticle was in turn modified in two different ways, through the introduction of NH2 or COOH functional groups, in order to make their surface positively or negatively charged.SiO2 NPs were intravenously administered to pregnant mice, through the injection into the venous retro-bulbar eye plexus. Administration was performed at two different gestational stages. A group of females received the material 5.5 days after conception, when the placenta is still poorly formed, while a second group was exposed at 12.5 day of pregnancy, a time at which the placenta has completed development. The difference in the administration timing allowed us to evaluate the possible differences in susceptibility of the fetus depending at different stages of placental development. Our results have shown that the smallest SiO2 NP have a high biocompatibility and do not interfere with the development of the embryo, or with placental development. In contrast, the NPs of medium and large size have demonstrated interference with the development of the fetus, leading to the onset of mild structural alterations and the appearance of a large number of identical twins, an extremely rare phenomenon in rodents, generally secondary to a mild teratogenic stimulus. Such effect became apparent only after administration of high doses of nano pa