In vitro hazard assessment of nanoparticles developed for biomedical applications

Nanotechnology is a growing sector in industry for twenty years and nanomaterials are currently used in numerous industrials applications. Their interest is based on their dimensions and their shape that give them very particular technological and biological properties. However, the development of these nanoparticles, their industrial preparation and integration into various products already involve an initial increased of human exposure (via inhalation, percutaneous and oral route). Another exposure pathway exists and is represented by drug injections. The risks associated with these new technologies and new products are still unclear. After a characterization step (zeta potential, TEM, TGA, DLS, XPS, IR measurements …), different toxicological endpoints were analyzed in vitro. However, bioassay protocols need to be adapted to nanoparticles. Cytotoxicity was assessed with the RNA synthesis inhibition assay, which is an early very sensitive sublethal bioassay. Oxidative stress was detected using DCF-DA assay for a sensitive and rapid quantitation of oxygen-reactive species. For genotoxicity, the comet assay performed in presence of Formamido-Pyrimidine-Glycosylase (FPG) detects low levels of DNA damage relative to DNA oxidative damage. Finally a short-term cell transformation assay (CTA) was performed, using the Bhas 42 cell line to distinguish between tumor initiators and promotors properties. Nanoparticles (SPIONs and titanate nanotubes (TiONts)) didn't induce any cytotoxic, genotoxic and oxidative response after a 24h treatment with concentrations up to 100 µg/mL in the human HepG2 cell line. However, TiONts induced a positive dose dependent response in the CTA assay at the initiation step (1-10 µg/mL)