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

Abstract

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.

Keywords::

• Nanomaterial
• TiO₂
• CeO₂
• immuno-spin trapping
• oxidative stress

Acknowledgements

We thank Drs Will Boyes and Kevin Dreher for reviewing this manuscript as part of EPA clearance procedures. Dr Kevin Dreher coordinated the characterization of the eight nanomaterials used in this study via a contract for analytical chemistry and physical chemistry parameters with the University of Kentucky which was administered by Dr Eric Grulke in the Engineering School. Kevin Dreher also compiled the physical characterization data presented in Table I. We are grateful to Drs Ron Mason and Dario Ramirez for assisting us in getting the IST assay established in our laboratory.

Declaration of interest: This manuscript has been reviewed in accordance with the policy of the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.