title: Stable colloidal dispersions of C60 fullerenes in water: evidence for genotoxicity.
abstract: Stable aqueous suspensions of colloidal C60 fullerenes free of toxic organic solvents were prepared by two methods: ethanol to water solvent exchange (EthOH/nC60 suspensions) and extended mixing in water (aqu/nC60 suspensions). The extended mixing method resulted in the formation of larger (dp approximately 178 nm) and less negatively charged (zeta approximately -13.5 mV) nC60 colloids than nC60 prepared by ethanol to water solvent exchange (dp approximately 122 nm, zeta approximately -31.6 mV). Genotoxicity of these suspensions was evaluated with respect to human lymphocytes using single-cell gel electrophoresis assay (Comet assay). The assay demonstrated genotoxicity for both types of suspensions with a strong correlation between the genotoxic response and nC60 concentration, and with genotoxicity observed at concentrations as low as 2.2 microg/L for aqu/nC60 and 4.2 microg/L for EtOH/nC60. The Olive tail moments (OTM) for these two concentrations were 1.54 +/- 0.24 and 1.34 +/- 0.07, respectively, which in comparison to the negative control OTM of 0.98 +/- 0.17 is statistically different with a p value of at least 0.05. Aqu/nC60 suspensions elicited higher genotoxic response than EthOH/nC60 for the same nC60 concentration. The results represent the first genotoxicity data for colloidal fullerenes produced by simple mixing in water.
authors.affiliation: Developmental Toxicology Division, Industrial Toxicology Research Centre, P.O. Box 80, Mahatma Gandhi Marg, Lucknow, 226 001, India.
authors.forename: Alok
authors.initials: A
authors.lastname: Dhawan
authors.forename: Julian S
authors.initials: JS
authors.lastname: Taurozzi
authors.forename: Alok K
authors.initials: AK
authors.lastname: Pandey
authors.forename: Wenqian
authors.initials: W
authors.lastname: Shan
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Miller
authors.forename: Syed A
authors.initials: SA
authors.lastname: Hashsham
authors.forename: Volodymyr V
authors.initials: VV
authors.lastname: Tarabara
mesh_terms: D003102:Colloids; D020552:Comet Assay; D004247:DNA / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004586:Electrophoresis; D000431:Ethanol; D037741:Fullerenes / Q000737:chemistry* / Q000633:toxicity*; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D037741:Fullerenes; D014867:Water; D000431:Ethanol; D004247:DNA; C069837:fullerene C60