Genotoxic and oxidative damage of shape-ebgineered Titanium dioxide nanoparticoles (TiO2-NPs) in bronchial epithelial cells.

Different studies on titanium dioxide nanoparticles (TiO2-NPs) genotoxicity 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 and coatings) can influence biological effects. The aim of this study was to evaluate the genotoxic effect of three engineered TiO2-NPs shapes (bipyramids, rods and platelet NPs) in bronchial epithelial cells (BEAS-2B) in comparison with two commercial TiO2-NPs (p25 and food grade). Detailed characteristics of TiO2-NPs dispersions were defined (T-SEM, DLS by SETNanoMetro project). BEAS-2B were exposed to different doses of TiO2-NPs (range 0 - 120 µg/ml) for 24h (1h light, 23h dark). Genotoxic and oxidative damage was assessed by Comet assay (with/without Fpg enzyme). Cytotoxic effects were also evaluated by cell viability assays (WST-1) and membrane damage (LDH assay). Moderate viability reduction (88-96%, p<0.05) was detected in BEAS-2B exposed to the highest concentration of all TiO2-NPs. No significant membrane damage was observed confirming the low cytotoxic effect. A significant (p<0.05) dose-response 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) and it could be 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 (i.e. paints, foods, cosmetics, pharmaceuticals).