title: Salinity-dependent toxicity of water-dispersible, single-walled carbon nanotubes to Japanese medaka embryos.
abstract: To investigate the effects of salinity on the behavior and toxicity of functionalized single-walled carbon nanotubes (SWCNTs), which are chemical modified nanotube to increase dispersibility, medaka embryos were exposed to non-functionalized single-walled carbon nanotubes (N-SWCNTs), water-dispersible, cationic, plastic-polymer-coated, single-walled carbon nanotubes (W-SWCNTs), or hydrophobic polyethylene glycol-functionalized, single-walled carbon nanotubes (PEG-SWCNTs) at different salinities, from freshwater to seawater. As reference nanomaterials, we tested dispersible chitin nanofiber (CNF), chitosan-chitin nanofiber (CCNF) and chitin nanocrystal (CNC, i.e. shortened CNF). Under freshwater conditions, with exposure to 10 mg l-1W-SWCNTs, the yolk sacks of 57.8% of embryos shrank, and the remaining embryos had a reduced heart rate, eye diameter and hatching rate. Larvae had severe defects of the spinal cord, membranous fin and tail formation. These toxic effects increased with increasing salinity. Survival rates declined with increasing salinity and reached 0.0% in seawater. In scanning electron microscope images, W-SWCNTs, CNF, CCNF and CNC were adsorbed densely over the egg chorion surface; however, because of chitin's biologically harmless properties, only W-SWCNTs had toxic effects on the medaka eggs. No toxicity was observed from N-SWCNT and PEG-SWCNT exposure. We demonstrated that water dispersibility, surface chemistry, biomedical properties and salinity were important factors in assessing the aquatic toxicity of nanomaterials. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Graduate School of Life Sciences, Toyo University, Gunma, 374-0193, Japan.
authors.forename: Chisato
authors.identifier: 0000-0002-6901-0819
authors.initials: C
authors.lastname: Kataoka
authors.affiliation: Department of Life Sciences, Toyo University, Gunma, 374-0193, Japan.
authors.forename: Kousuke
authors.initials: K
authors.lastname: Nakahara
authors.affiliation: Graduate School of Life Sciences, Toyo University, Gunma, 374-0193, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Shimizu
authors.affiliation: Department of Life Sciences, Toyo University, Gunma, 374-0193, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kowase
authors.affiliation: Graduate School of Life Sciences, Toyo University, Gunma, 374-0193, Japan.|Department of Life Sciences, Toyo University, Gunma, 374-0193, Japan.|Research Center for Life and Environmental Sciences, Toyo University, Gunma, 374-0193, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Nagasaka
authors.affiliation: Graduate School of Engineering, Tottori University, Tottori, 680-8550, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ifuku
authors.affiliation: Graduate School of Life Sciences, Toyo University, Gunma, 374-0193, Japan.|Department of Life Sciences, Toyo University, Gunma, 374-0193, Japan.|Research Center for Life and Environmental Sciences, Toyo University, Gunma, 374-0193, Japan.|Bio-Nano Electronics Research Center, Toyo University, Saitama, 350-8585, Japan.
authors.forename: Shosaku
authors.initials: S
authors.lastname: Kashiwada
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000473:pathology; D000818:Animals; D002686:Chitin / Q000737:chemistry; D002823:Chorion / Q000737:chemistry / Q000473:pathology; D004625:Embryo, Nonmammalian / Q000473:pathology*; D047108:Embryonic Development / Q000187:drug effects; D005618:Fresh Water / Q000737:chemistry; D007814:Larva; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000633:toxicity*; D009990:Oryzias / Q000502:physiology*; D054712:Salinity; D012623:Seawater / Q000737:chemistry; D015017:Yolk Sac / Q000473:pathology
chemical_list: D037742:Nanotubes, Carbon; D002686:Chitin
keywords: carbon nanotube; chitin nanomaterial; embryo; medaka; salinity; toxicity