Agglomeration of Escherichia coli with Positively Charged Nanoparticles Can Lead to Artifacts in a Standard Caenorhabditis elegans Toxicity Assay

The increased use and incorporation of engineered nanoparticles (ENPs) in consumer products requires a robust assessment of their potential environmental implications. However, a lack of standardized methods for nanotoxicity testing has yielded results that are sometimes contradictory. Standard ecot...

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Bibliographic Details
Published inEnvironmental science & technology Vol. 52; no. 10; pp. 5968 - 5978
Main Authors Hanna, Shannon K, Montoro Bustos, Antonio R, Peterson, Alexander W, Reipa, Vytas, Scanlan, Leona D, Hosbas Coskun, Sanem, Cho, Tae Joon, Johnson, Monique E, Hackley, Vincent A, Nelson, Bryant C, Winchester, Michael R, Elliott, John T, Petersen, Elijah J
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 15.05.2018
Subjects
Animals
Assaying
Bacteria
Caenorhabditis elegans
Consumer goods
Consumer products
E coli
Environmental assessment
Escherichia coli
Food supply
Gold
Nanoparticles
Nematodes
Polystyrene
Polystyrene resins
Reproduction
Studies
Test procedures
Toxicity
Worms
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Summary:The increased use and incorporation of engineered nanoparticles (ENPs) in consumer products requires a robust assessment of their potential environmental implications. However, a lack of standardized methods for nanotoxicity testing has yielded results that are sometimes contradictory. Standard ecotoxicity assays may work appropriately for some ENPs with minimal modification but produce artifactual results for others. Therefore, understanding the robustness of assays for a range of ENPs is critical. In this study, we evaluated the performance of a standard Caenorhabditis elegans (C. elegans) toxicity assay containing an Escherichia coli (E. coli) food supply with silicon, polystyrene, and gold ENPs with different charged coatings and sizes. Of all the ENPs tested, only those with a positively charged coating caused growth inhibition. However, the positively charged ENPs were observed to heteroagglomerate with E. coli cells, suggesting that the ENPs impacted the ability of nematodes to feed, leading to a false positive toxic effect on C. elegans growth and reproduction. When the ENPs were tested in two alternate C. elegans assays that did not contain E. coli, we found greatly reduced toxicity of ENPs. This study illustrates a key unexpected artifact that may occur during nanotoxicity assays.
Bibliography:Current address: Department of Pesticide Regulation, California Environmental Protection Agency, 1001 I Street, Sacramento, CA 95814
Current address: Center for Tobacco Products, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.7b06099