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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.

SUBMITTER: Kim KT

PROVIDER: S-EPMC4034258 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Embryonic toxicity changes of organic nanomaterials in the presence of natural organic matter.

Kim Ki-Tae KT Jang Min-Hee MH Kim Jun-Yeol JY Xing Baoshan B Tanguay Robert L RL Lee Byeong-Gweon BG Kim Sang Don SD

The Science of the total environment 20120426

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 ...[more]

PMID: 22542237

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Project description:Heterogeneous phase astrochemistry plays an important role in the synthesis of complex organic matter (COM) as found on comets and rocky body surfaces like asteroids, planetoids, moons and planets. The proposed catalytic model is based on two assumptions: (a) siliceous rocks in both crystalline or amorphous states show surface-exposed defective centers such as siloxyl (Si-O•) radicals; (b) the second phase is represented by gas phase CO molecules, an abundant C1 building block found in space. By means of quantum chemistry; (DFT, PW6B95/def2-TZVPP); the surface of a siliceous rock in presence of CO is modeled by a simple POSS (polyhedral silsesquioxane) where a siloxyl (Si-O•) radical is present. Four CO molecules have been consecutively added to the Si-O• radical and to the nascent polymeric CO (pCO) chain. The first CO insertion shows no activation free energy with ΔG200K = -21.7 kcal/mol forming the SiO-CO• radical. The second and third CO insertions show Δ G200K‡ ≤ 10.5 kcal/mol. Ring closure of the SiO-CO-CO• (oxalic anhydride) moiety as well as of the SiO-CO-CO-CO• system (di-cheto form of oxetane) are thermodynamically disfavored. The last CO insertion shows no free energy of activation resulting in the stable five member pCO ring, precursor to 1,4-epoxy-1,2,3-butanone. Hydrogenation reactions of the pCO have been considered on the SiO oxygen or on the carbons and oxygens of the pCO chains. The formation of the reactive aldehyde SiO-CHO on the siliceous surface is possible. In principle, the complete hydrogenation of the (CO)1-4 series results in the formation of methanol and polyols. Furthermore, all the SiO-pCO intermediates and the lactone 1,4-epoxy-1,2,3-butanone product in its radical form can be important building blocks in further polymerization reactions and/or open ring reactions with H (aldehydes, polyols) or CN (chetonitriles), resulting in highly reactive multi-functional compounds contributing to COM synthesis.

Dataset Information

Embryonic toxicity changes of organic nanomaterials in the presence of natural organic matter.

Publications

Embryonic toxicity changes of organic nanomaterials in the presence of natural organic matter.

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