Impact of Titanium Dioxide Nanoparticle Dispersion State and Dispersion Method on Their Toxicity Towards A549 Lung Cells and Escherichia coli Bacteria

摘要

Titanium-dioxide nanoparticle (TiO_2-NPs) dispersion for toxicological studies is classically achieved by high power sonication. The aim of this study was to compare the dispersion state resulting from different dispersion techniques, and to correlate dispersion state and dispersion method to in vitro toxicity in a final view to contribute to the very active field of establishing protocols for reliable NP toxicity testing. To achieve this objective, several dispersion methods were applied to Evonik P25 TiO_2-NPs. The dispersion state, as well as the stability of these TiO_2-NP suspensions were evaluated by photon correlation spectroscopy (PCS) and turbidimetry. A549 human lung cells and Escherichia coli (E. coli) bacteria were exposed to these TiO_2-NP suspensions. Cytotoxicity, alteration of cell membrane integrity and intracellular accumulation of reactive oxygen species (ROS) were measured. Our results show that ultrasonication and ball milling both lead to well dispersed TiO_2-NP suspensions. Cytotoxicity depends on dispersion state while cell membrane integrity and intracellular accumulation of ROS seem more dependent on the dispersion method. In particular, ultrasonication leads to the most deleterious effects, as compared to ball milling, while the dispersion state is similar. Moreover TiO_2-NPs coated with proteins lead to less damage than uncoated TiO_2-NPs.