The role of reactive oxygen species in silicon dioxide nanoparticle-induced cytotoxicity and DNA damage in HaCaT cells

The increasing applications of silicon dioxide (SiO2) nanomaterials have been widely concerned over their biological effects and potential hazard to human health. In this study, we explored the effects of SiO2 nanoparticles (15, 30, and 100 nm) and their micro-sized counterpart on cultured human epidermal Keratinocyte (HaCaT) cells. Cell viability, cell morphology, reactive oxygen species (ROS), DNA damage (8-OHdG, gamma H2AX and comet assay) and apoptosis were assessed under control and SiO2 nanoparticles exposed conditions. As observed in the Cell Counting Kit-8 (CCK-8) assay, exposure to 15, 30 or 100 nm SiO2 nanoparticles at dosage levels between 0 and 100 mu g/ml decreased cell viability in a concentration- and size dependent manner and the IC50 of 24 hour exposure was 19.4 +/- A 1.3, 27.7 +/- A 1.5 and 35.9 +/- A 1.6 mu g/ml for 15, 30 and 100 nm SiO2 nanoparticles, respectively. Morphological examination revealed cell shrinkage and cell wall missing after SiO2 nanoparticle exposure. Increase in intracellular ROS level and DNA damage as well as apoptosis were also observed in SiO2 nanoparticle-exposed HaCaT cells. Exposure to SiO2 nanoparticles results in a concentration- and size-dependent cytotoxicity and DNA damage in cultural HaCaT cells which is closely correlated to increased oxidative stress.