The High-Throughput In Vitro CometChip Assay for the Analysis of Metal Oxide Nanomaterial Induced DNA Damage

Metal oxide nanomaterials (MONMs) are among the most highly utilized classes of nanomaterials worldwide, though their potential to induce DNA damage in living organisms is known. High-throughput in vitro assays have the potential to greatly expedite analysis and understanding of MONM induced toxicity while minimizing the overall use of animals. In this study, the high-throughput CometChip assay was used to assess the in vitro genotoxic potential of pristine copper oxide (CuO), zinc oxide (ZnO), and titanium dioxide (TiO₂) MONMs and microparticles (MPs), as well as five coated/surface-modified TiO₂ NPs and zinc (II) chloride (ZnCl₂) and copper (II) chloride (CuCl₂) after 2-4 h of exposure. The CuO NPs, ZnO NPs and MPs, and ZnCl₂ exposures induced dose- and time-dependent increases in DNA damage at both timepoints. TiO₂ NPs surface coated with silica or silica-alumina and one pristine TiO₂ NP of rutile crystal structure also induced subtle dose-dependent DNA damage. Concentration modelling at both post-exposure timepoints highlighted the contribution of the dissolved species to the response of ZnO, and the role of the nanoparticle fraction for CuO mediated genotoxicity, showing the differential impact that particle and dissolved fractions can have on genotoxicity induced by MONMs. The results imply that solubility alone may be insufficient to explain the biological behaviour of MONMs.