title: Carbon and clay nanoparticles induce minimal stress responses in gram negative bacteria and eukaryotic fish cells.
abstract: We investigated in vitro the potential mutagenic and toxic effects of two clay-based nanoparticles, Cloisite® Na(+) (Cloisite) and halloysite; and multi-walled carbon nanotubes (MWCNT), commonly used in the polymer composite industry. Using the Ames test, the three nanoparticles did not have a true mutagenic effect, although growth of Salmonella enterica var. Typhimurium (S.typhimurium) was diminished at higher nanoparticle concentrations. We investigated the impact of nanoparticles on Escherichia coli and S. typhimurium including oxyR and rpoS mutants, which are susceptible to oxidative stress. The oxyR mutants were inhibited in the presence of nanoparticles, when grown aerobically with light. Toxicity was not observed in the absence of light or during anaerobic growth. E. coli rpoS mutants exhibited some toxicity when cultured with Cloisite and MWCNT only when grown aerobically with light. There was no effect with other nanoparticles, or with S. typhimurium rpoS mutants. MWCNT exhibited a slight toxic effect against Epithelioma papulosum cyprini (EPC) cells only at the highest concentration tested. There was no discernable toxicity to EPC cells caused by the clay nanoparticles. We conclude that clay-based nanoparticles and MWCNT do not exert a mutagenic effect and do not have a general toxic effect across all bacterial species or between prokaryotic and eukaryotic cells. Modest toxicity was only observed in eukaryotic EPC cells against MWCNT at the highest concentration tested. Limited species-specific toxicity to clay based and MWCNT nanoparticles was seen in bacterial strains primarily due to culture conditions and mutations that exacerbate oxidative stress.
authors.affiliation: Department of Biology, Texas State University-San Marcos, 601 University Drive, San Marcos, Texas 78666, USA.
authors.forename: Alicia A
authors.initials: AA
authors.lastname: Taylor
authors.forename: Gary M
authors.initials: GM
authors.lastname: Aron
authors.forename: Gary W
authors.initials: GW
authors.lastname: Beall
authors.forename: Nihal
authors.initials: N
authors.lastname: Dharmasiri
authors.forename: Yixin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Robert J C
authors.initials: RJ
authors.lastname: McLean
mesh_terms: D000538:Aluminum Silicates / Q000633:toxicity*; D000818:Animals; D002460:Cell Line; D000077215:Clay; D004249:DNA Damage; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005399:Fishes / Q000378:metabolism*; D037742:Nanotubes, Carbon / Q000633:toxicity*; D018384:Oxidative Stress; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics; D018675:Toxicity Tests
chemical_list: D000538:Aluminum Silicates; D037742:Nanotubes, Carbon; D000077215:Clay
keywords: Ames test; Escherichia coli; Salmonella typhimurium; nanoparticle; oxidative stress; toxicity