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Levard C.,Aix - Marseille University | Masion A.,Aix - Marseille University | Rose J.,Aix - Marseille University | Doelsch E.,International Consortium for the Environmental Implications of Nanotechnology ICEINT | And 11 more authors.
Physical Chemistry Chemical Physics | Year: 2011

The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 °C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from nOH/n Al = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: nOH/nAl = 1.5 for the formation of nanotubes with structural defects, nOH/nAl = 2 for the synthesis of a well crystallized Ge imogolite and nOH/nAl > 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube's crystallinity opens up interesting opportunities in regard to new potential applications. © the Owner Societies 2011.

Auffan M.,Aix - Marseille University | Masion A.,Aix - Marseille University | Labille J.,Aix - Marseille University | Diot M.-A.,Aix - Marseille University | And 9 more authors.
Environmental Pollution | Year: 2014

A multi-scale methodology was used to characterize the long-term behavior and chemical stability of a CeO2-based nanocomposite used as UV filter in wood stains. ATR-FTIR and 13C NMR demonstrated that the citrate coated chelates with Ce(IV) through its central carboxyl- and its α-hydroxyl- groups at the surface of the unaged nanocomposite. After 42 days under artificial daylight, the citrate completely disappeared and small amount of degradation products remained attached to the surface even after 112 days. Moreover, the release/desorption of the citrate layer led to a surface reorganization of the nano-sized CeO2 core observed by XANES (Ce L3-edge). Such a surface and structural transformation of the commercialized nanocomposite could have implications in term of fate, transport, and potential impacts towards the environment. © 2014 Elsevier Ltd. All rights reserved.

Bour A.,Ecolab | Mouchet F.,Ecolab | Cadarsi S.,Ecolab | Silvestre J.,Ecolab | And 16 more authors.
Nanotoxicology | Year: 2016

The toxicity of CeO2 NPs on an experimental freshwater ecosystem was studied in mesocosm, with a focus being placed on the higher trophic level, i.e. the carnivorous amphibian species Pleurodeles waltl. The system comprised species at three trophic levels: (i) bacteria, fungi and diatoms, (ii) Chironomus riparius larvae as primary consumers and (iii) Pleurodeles larvae as secondary consumers. NP contamination consisted of repeated additions of CeO2 NPs over 4 weeks, to obtain a final concentration of 1 mg/L. NPs were found to settle and accumulate in the sediment. No effects were observed on litter decomposition or associated fungal biomass. Changes in bacterial communities were observed from the third week of NP contamination. Morphological changes in CeO2 NPs were observed at the end of the experiment. No toxicity was recorded in chironomids, despite substantial NP accumulation (265.8 ± 14.1 mg Ce/kg). Mortality (35.3 ± 6.8%) and a mean Ce concentration of 13.5 ± 3.9 mg/kg were reported for Pleurodeles. Parallel experiments were performed on Pleurodeles to determine toxicity pathways: no toxicity was observed by direct or dietary exposures, although Ce concentrations almost reached 100 mg/kg. In view of these results, various toxicity mechanisms are proposed and discussed. The toxicity observed on Pleurodeles in mesocosm may be indirect, due to microorganisms interaction with CeO2 NPs, or NP dissolution could have occurred in mesocosm due to the structural complexity of the biological environment, resulting in toxicity to Pleurodeles. This study strongly supports the importance of ecotoxicological assessment of NPs under environmentally relevant conditions, using complex biological systems. © 2015 Informa UK Ltd.

Tella M.,Aix - Marseille University | Auffan M.,Aix - Marseille University | Brousset L.,International Consortium for the Environmental Implications of Nanotechnology ICEINT | Brousset L.,Aix - Marseille University | And 14 more authors.
Environmental Science: Nano | Year: 2015

Indoor aquatic mesocosms were designed to mimic pond ecosystems contaminated by a continuous point-source discharge of cerium oxide nanoparticles (CeO2-NPs). Bare and citrate-coated CeO2-NPs exhibited different chemical and colloidal behaviors in the aquatic mesocosms. Bare CeO2-NPs were chemically stable but quickly homo-aggregated and settled out of the water column. Citrate-coated NPs both homo- and hetero-aggregated but only after the several days required to degrade the citrate coating. While they were more stable as a colloidal suspension, coated CeO2-NPs dissolved faster due to surface complexation with citrate, which resulted in the release of dissolved Ce into the water column. The different distributions over time between water/sediment or dissolved/particulate forms of Ce controlled the availability of Ce to benthic grazers (mollusk Planorbarius corneus) and planktonic filter feeders (copepod Eudiaptomus vulgaris). © The Royal Society of Chemistry 2015.

Marie T.,Aix - Marseille University | Melanie A.,Aix - Marseille University | Lenka B.,International Consortium for the Environmental Implications of Nanotechnology ICEINT | Lenka B.,Aix - Marseille University | And 13 more authors.
Environmental Science and Technology | Year: 2014

Mesocosms are an invaluable tool for addressing the complex issue of exposure during nanoecotoxicological testing. This experimental strategy was used to take into account parameters as the interactions between the NPs and naturally occurring (in)organic colloids (heteroaggregation), or the flux between compartments of the ecosystems (aqueous phase, sediments, biota) when assessing the impacts of CeO2 NPs in aquatic ecosystems. In this study, we determine the transfer, redox transformation, and impacts of 1 mg L-1 of bare and citrate coated CeO2-NPs toward an ecologically relevant organism (snail, Planorbarius corneus) exposed 4 weeks in a complex experimental system mimicking a pond ecosystem. Over time, CeO 2-NPs tend to homo- and heteroaggregate and to accumulate on the surficial sediment. The kinetic of settling down was coating-dependent and related to the coating degradation. After 4 weeks, Ce was observed in the digestive gland of benthic organisms and associated with 65-80% of Ce IV reduction into CeIII for both bare and coated CeO 2 NPs. A transitory oxidative stress was observed for bare CeO 2-NPs. Coated-NPs exposed snails did not undergo any lipid peroxidation nor change in the antioxidant contents, while Ce content and reduction in the digestive gland were identical to bare CeO2-NPs. We hypothesized that the presence of citrate coating enhanced the defense capacity of the cells toward the oxidative stress induced by the CeO2 core. © 2014 American Chemical Society.

Garaud M.,CNRS Interdisciplinary Laboratory for Continental Environments | Auffan M.,International Consortium for the Environmental Implications of Nanotechnology iCEINT | Auffan M.,Aix - Marseille University | Devin S.,CNRS Interdisciplinary Laboratory for Continental Environments | And 8 more authors.
Nanotoxicology | Year: 2016

Exposures in realistic environmental conditions are essential to properly assess the effects of emerging pollutants on ecosystems. While ceria nanoparticles (nCeO2) production and use are expanding quickly, ecotoxicity studies remain very scarce. In this study, we set up experimental systems reproducing a simplified ecosystem to assess the effects of a chronic exposure to citrate-coated nCeO2 (ci-CeO2) and bare nCeO2 (ba-CeO2) on the freshwater mussel Dreissena polymorpha using an integrated multibiomarker approach. The fate of nanoparticles was tightly monitored to properly characterize the exposure. Organisms were exposed for 3 weeks and sampled weekly for biomarker analysis. Mussel filter-feeding activity resulted in significant removal of nCeO2 from the water column. At the same time, bioaccumulation was low, reaching its maximum in the first week. Mussels bioaccumulated ci-CeO2 three times more than ba-CeO2, probably due to coating-related differences in their behavior in the water column and in organisms. Meanwhile, biomarker results were integrated and synthesized using linear discriminant analysis, highlighting that pi-glutathione-S-transferase (piGST) mRNA, catalase (CAT) activity and lysosomal system were the most impacted of the seven biomarkers singled out by the discriminant analysis. These biomarker responses indicated that mussels exposed to both forms of nCeO2 were stressed and differentiate from the controls. Moreover, they responded differently to ba-CeO2 and ci-CeO2 exposure. However, biomarkers used in the experimental conditions of this study did not indicate severe nCeO2 toxicity on mussels, as cellular damage biomarkers and mussel filtering activity were left unimpaired. However, further studies are needed to investigate if the slight perturbations observed could lead to populational impacts in the long term. © 2016 Taylor & Francis

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