title: Embryonic toxicity changes of organic nanomaterials in the presence of natural organic matter.
abstract: When elucidating the potential fate and bioavailability of nanomaterials (NMs) in an aquatic system, it is important to consider the interactions between NMs and natural organic matter (NOM). The present study compared the toxicities of carbon-based NMs, with disparate physicochemical properties, on Japanese medaka (Oryzias latipes) embryos after the addition of NOM. The measured embryonic toxicity parameters were mortality, malformation and hatching delay. Various physicochemical properties of water suspended fullerenes (nC(60)) and multi-walled carbon nanotubes (MWNTs) were modulated by organic exchange (Tol/nC(60)), stirring over time (Aqu/nC(60)) and acid treatment (f-MWNTs) followed by characterization. Tol/nC(60) produced relatively more hydrophobic surfaces and exhibited smaller closed spherical agglomerates than Aqu/nC(60). Acid-treated f-MWNTs displayed functionalized hydrophilic surfaces compared to raw MWNTs (r-MWNTs). The resultant embryonic toxicities, in the absence of NOM, were ranked in the order: f-MWNTs>Tol/nC(60)>Aqu/nC(60). As the NOM concentrations were increased, no changes in embryonic toxicities were observed on exposure of Aqu/nC(60) and r-MWNTs; whereas, the toxicities were reduced on exposure to Tol/nC(60) and f-MWNTs, due to a disappearance of hydrophobic primary spherical aggregates and partial coating, respectively. These data suggest that in the presence of NOM, the morphological differences of NMs, as well as their physicochemical properties, play a significant role in their reactions and subsequent medaka embryonic nanotoxicity.
authors.affiliation: Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology(GIST), 261 Cheom-dan Gwagi-ro, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Ki-Tae
authors.initials: KT
authors.lastname: Kim
authors.forename: Min-Hee
authors.initials: MH
authors.lastname: Jang
authors.forename: Jun-Yeol
authors.initials: JY
authors.lastname: Kim
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
authors.forename: Robert L
authors.initials: RL
authors.lastname: Tanguay
authors.forename: Byeong-Gweon
authors.initials: BG
authors.lastname: Lee
authors.forename: Sang Don
authors.initials: SD
authors.lastname: Kim
mesh_terms: D000327:Adsorption; D000818:Animals; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D006812:Humic Substances; D049329:Nanostructures / Q000737:chemistry / Q000633:toxicity*; D009990:Oryzias; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical