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Unique Nanoparticle Optical Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Screening and Ranking
Citation:
Dreher, K. AND W. Polk. Unique Nanoparticle Optical Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Screening and Ranking. Society of Toxicology, New Orleans, LA, March 13 - 17, 2016.
Impact/Purpose:
Research reported here demonstrates that many of the available HTS fluorescent based assays can be confounded by metal oxide NPs and that their use without careful controls or adequate adjustments can result in both false positive and false negative errors.
Description:
Nanoparticles (NPs) are novel materials having at least one dimension less than 100 nm and display unique physicochemical properties due to their nanoscale size. An emphasis has been placed on developing high throughput screening (HTS) assays to characterize and rank the toxicities of chemicals in a manner consistent with the vision of the Toxicology in the 21st Century Vision. Research reported here demonstrates that many of the available HTS fluorescent based assays can be confounded by metal oxide NPs and that their use without careful controls or adequate adjustments 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 NPs ranging in size from 7 to 250 nm and varying in composition as well as crystalline structure. NP optical 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 analytical analysis of NP dispersions alone. The effects are demonstrated to be NP dependent and not predictable by elemental composition, purity, or primary particle size. In addition, NP optical properties were found to interfere with the ability to determine the extent to which oxidative stress contributed to titanium oxide NP toxicity within endothelial cells. It is concluded that data generated by HTS assays have the potential to be impacted by NP optical interference requiring adjustments to be made for each NP within an in vitro testing system prior to the initiation of toxicity screening. This abstract does not represent EPA policy. Research partially funded by the USEPA - UNC Cooperative Training Agreement CR-83515201