SiO2 Nanoparticule-induced size-dependent genotoxicity - an in vitro study using sister chromatid exchange, micronucleus and comet assay

Fine particles with a characteristic size smaller than 100 nm (i.e. nanoparticlesspread out in nowadays life. Silicon or Si, is one of the most abundant chemical elements found on the Earth. Its oxide forms, such as silicate (SiO4) and silicon dioxide, also known as silica (SiO2), are the main constituents of sand and quartz contributing to 90% of the Earth's crust. In this work, three genotoxicity systems "sister chromatid exchange, cytokinesis block micronucleus test and single cell gel electrophoresis (comet) assay'' were employed to provide further insight into the cytotoxic and mutagenic/genotoxic potential of SiO2 nanoparticules (particle size 6 nm, 20 nm, 50 nm) in cultured peripheral blood lymphocytes as in vitro. It was observed that there is a significant decrease in Mitotic index (MI), Cytokinesis block proliferation index (CBPI), proliferation index (PRI) values expressed as Cell Kinetic parameters compared with negative control (p<0.05). There is a statistically significant difference between negative control culture and culture exposed to SiO2 (6 nm, 20 nm, 50 nm) (p<0.01, p<0.01, p<0.05, respectively). It is found that SiO2 nanoparticles at different size (6, 20, 50 nm) progressively increased the SCE frequency and DNA damage on the basis the AU values compared with negative control (p<0.05). Results showed that the genotoxic/mutagenic and cytotoxic effects of SiO2 nanoparticules is dependent to particule size.