Shape-engineered titanium dioxide nanoparticles (TiO2-NPs): Cytotoxicity and genotoxicity in bronchial epithelial cells

Different studies on titanium dioxide nanoparticles (TiO2-NPs) toxicity have been conducted but no clear accordance exists among mechanism of action. Many physico-chemical properties of TiO2-NPs (i.e. shape, crystal structure, aggregation) can influence biological effects. The aim of this study was to evaluate cytotoxicity and genotoxicity of three engineered TiO2-NPs shapes (bipyramids, rods, platelet NPs) in bronchial epithelial cells (BEAS-2B) in comparison with commercial TiO2-NPs (p25 and food grade). Detailed characteristics of TiO2-NPs were defined (T-SEM, DLS by SETNanoMetro project). BEAS-2B were exposed to TiO2-NPs (range 0 - 120g/ml) for 24 h (1 h light, 23 h dark). Cytotoxicity were evaluated by cell viability assays (WST-1) and membrane damage (LDH assay). DNA damage was assessed by Comet assay (with/without Fpg enzyme). Moderate viability reduction (88–96%, p < 0.05) was detected at the highest concentration of all TiO2-NPs. No significant membrane damage was observed confirming the low cytotoxic effect. A significant (p < 0.05) DNA damage (direct and oxidative) was induced by food grade NPs, while p25 showed only oxidative damage. Bipyramids and rods TiO2-NPs did not show any genotoxic effect; platelet TiO2-NPs induced direct and oxidative DNA damage at the highest doses (p < 0.05) probably related to the higher aggregation tendency. The commercial TiO2-NPs had a higher genotoxic effect than shape engineered ones, however the shape induced different genotoxic effects. This study suggests higher safety in using shape engineered TiO2-NPs for different technological applications.