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Unique Nanoparticle Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Testing and Ranking
Citation:
Dreher, K. AND W. Polk. Unique Nanoparticle Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Testing and Ranking. Presented at Society of Toxicology, March 10 - 14, 2013.
Impact/Purpose:
Research reported here demonstrates that many of the available high throughput screening (HTS) fluorescent based assays can be confounded by nanoparticles and that their use without careful controls can result in both false positive and false negative errors.
Description:
Nanomaterials are a diverse collection of novel materials that exhibit at least one dimension less than 100 nm and display unique chemical and physical properties due to their nanoscale size. An emphasis has been put on developing high throughput screening (HTS) assays to characterize and rank the toxicities of these materials in a manner consistent with the vision of the Toxicology in the 21st Century Initiative. Research reported here demonstrates that many of the available HTS fluorescent based assays can be confounded by nanoparticles and that their use without careful controls can result in both false positive and false negative errors. Effects are demonstrated for assays measuring cytotoxicity, oxidative stress, and nuclear content using commercially available metal oxide nanoparticles ranging in size from 7 to 250 nm and varying in crystalline structure. The confounding effects are demonstrated in a variety of primary human endothelial cell types and are shown to be more severe within cells than would be anticipated from analytic analysis. Moreover, the effects are demonstrated to be particle dependent and not predictable by elemental composition, purity, or primary particle size. The establishment of an improved technique is shown to completely alter the mechanistic understanding of titanium oxide nanoparticle toxicity within endothelial cells. It is concluded that a majority of available HTS assays have the potential to be impacted by particle interference and quality analysis is necessary for each particle within a model system prior to the initiation of screening programs. (This abstract dose not represent EPA policy. This work was partially funded by the USEPA – UNC Cooperative Training Agreement CR-83515201)