The comet assay in testing the potential genotoxicity of nanomaterials

Azqueta Amaya
2015 Frontiers in Genetics  
The large number of nanomaterial-based applications emerging in the materials and life sciences and the foreseeable increasing use of these materials require methods that evaluate and characterize the toxic potential of these nanomaterials to keep safety risks to people and environment as low as possible. As nanomaterial toxicity is influenced by a variety of parameters like size, shape, chemical composition, and surface chemistry, high throughput screening (HTS) platforms are recommended for
more » ... e recommended for assessing cytotoxicity. Such platforms are not yet available for genotoxicity testing. Here, we present first results obtained for application-relevant nanomaterials using an automatable genotoxicity platform that relies on the quantification of the phosphorylated histone H2AX (γ-H2AX) for detecting DNA double strand breaks (DSBs) and the automated microscope system AKLIDES® for measuring integral fluorescence intensities at different excitation wavelengths. This platform is used to test the genotoxic potential of 30 nm-sized citrate-stabilized gold nanoparticles (Au-NPs) as well as micellar encapsulated iron oxide nanoparticles (FeO x -NPs) and different cadmium (Cd)-based semiconductor quantum dots (QDs), thereby also searching for positive and negative controls as reference materials. In addition, the influence of the QD shell composition on the genotoxic potential of these Cd-based QDs was studied, using CdSe cores as well as CdSe/CdS core/shell and CdSe/ CdS/ZnS core/shell/shell QDs. Our results clearly revealed the genotoxicity of the Au-NPs and its absence in the FeO x -NPs. The genotoxicity of the Cd-QDs correlates with the shielding of their Cd-containing core, with the core/shell/shell architecture preventing genotoxicity risks. The fact that none of these nanomaterials showed cytotoxicity at the chosen particle concentrations in a conventional cell viability assay underlines the importance of genotoxicity studies to assess the hazardous potential of nanomaterials. † Electronic supplementary information (ESI) available: TEM images of the Au-NPs and FeO x -NPs (Fig. S1 ), TEM images of the Cd-based QDs (Fig. S2) , scheme of the micellar encapsulation strategy (Fig. S3) , number-weighted DLS size distributions (Fig. S4) , total amount of surface functional groups measured by conductometry (Table S1 ), comparison of the genotoxicity at 100 pM (Fig. S5) , detailed statistical analysis of genotoxicity of FeOx-NPs (negative control) (Fig. S6) , and detailed statistical analysis of genotoxicity of Au-NPs ( positive control) (Fig. S7) . See
doi:10.3389/conf.fgene.2015.01.00070 fatcat:zu6flcatnnbldamiueqcoucxyi