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, γH2AX 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 μg/ml decreased cell viability in a concentration- and size dependent manner and the IC50 of 24 hour exposure was 19.4 ± 1.3, 27.7 ± 1.5 and 35.9 ± 1.6 μg/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.