Oxidative stress studies of six TiO2 and two CeO2 nanomaterials: Immuno-spin trapping results with DNA

Six TiO2 and two CeO2 nanomaterials with dry sizes ranging from 6-410 nm were tested for their ability to cause DNA centered free radicals in vitro in the concentration range of 10-3,000 ug/ml. All eight of the nanomaterials significantly increased the adduction of the spin trap agent 5,5-dimethyl-1-pyroline N-oxide (DMPO) to DNA as measured by the experimental technique of immuno-spin trapping. The eight nanomaterials differed considerably in their potency, slope, and active concentration. The largest increase in DNA nitrone adducts was caused by a TiO2 nanomaterial (25 nm, anatase) from Alfa Aesar. Some nanomaterials that increased the amount of DNA nitrone adducts at the lowest exposure concentrations (100 ug/ml) were Degussa TiO2 (31 nm), Alfa Aesar TiO2 (25 nm, anatase) and Nanoamor CeO2 (8 nm, cerianite). At exposure concentrations of 10 or 30 ug/ml, no nanomaterials showed significant in vitro formation of DNA nitrone adducts.