Description: Das Projekt "Linking geochemistry of metal containing nanoparticles to their impact to microorganisms" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Ecole Polytechnique Federale de Lausanne (EPF), Institut d'Amenagement des Terres et des Eaux (IATE).The present project examines the interaction of engineered nanoparticles (NP) with microorganisms with a specific emphasis on NP bioavailability and effect on the membrane integrity and oxidative stress. Carboxyl-group functionalized polymeric coated CdSe/ZnS quantum dots (QDs) were chosen as model nanoparticles, because of their increasing use, water dispersibility and specific tailoring for bio-imaging related to the cellular uptake. NP dispersion stability in terms of number, hydrodynamic radius and fluorescence of the individual particles under conditions of microorganism exposure experiments were investigated. Obtained results demonstrated that at nanomolar concentrations QDs form stable dispersions under most freshwater conditions. Humic, fulvic and alginic acids, and extracellular polymeric substances, representing major groups of the aquatic dissolved organic matter affected insignificantly the stability of QDs. Acidic pH below 5 increased QDs dissolution, while micromolar concentrations of trace elements have no effect on their stability. Addition of microalgae and bacteria to QD dispersions produced a reduction of the number of QDs and a significant decline in the fluorescence of individual QDs. QDs associated to the studied microorganisms, however their bioavailability was dependent on the cell wall and surface envelop composition. Flow cytometry (FCM) demonstrated that the percentage of QD-positive cells decreased in the order: bacterium Cupriavidus metallidurans >> wall-less green alga Chlamydomonas reinhardtii (CW) >> wild type C. reinhardtii (WT) > green alga Chlorella kesslerii, thus confirming the importance of the cell wall as a protective barrier. The percentage of the QD-positive cells increased with exposure time and the concentration of QDs for C. metallidurans and CW C. reinhardtii, while no temporary or concentration dependence was found for WT C. reinhardtii and C. kesslerii. QDs enhanced the level of the reactive oxygen species in the bacterial cells and augmented the percentage of the cells with damaged and leaky membranes as probed by FCM in combination with 5-(and-6)-carboxy-2'7'-dichlorodihydrofluorescein diacetate and propidium iodide stains. No difference in the behaviour of amine- and carboxyl-PEG-QDs was found, suggesting that different functional groups in the surface coating have no effect on bacterium-QD interactions under the studied conditions.
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Blattgemüse ? Tierhaltungsanlage ? Amin ? Hydrodynamik ? Jodid ? Anstrich ? Geochemie ? Grünalgen ? Resistenz ? Sauerstoff ? Bakterien ? Fluoreszenz ? Mikroalgen ? Stress ? Organisches Material ? Süßwasser ? Wirkung ? Metall ? Bioverfügbarkeit ? Dispersion ? Exposition ? Wassernutzung ? Zelle ? Mikroorganismen ? Algen ? Wasser ? Stoff ? Wirkung ? Nanopartikel ? Chemischer Stoff ? Membran ? Partikel ? ERGEBNIS ? GRUPPE ? DAUER ? ABNAHME ? EXPERIMENT ? Erlass [Recht] ? OBERFLAECHE ? PROJEKT ? SPEZIFISCH ? FORMBLAETTER ? Fluss [Bewegung] ? Stall ? UNTER ? VERHAELTNIS ? VERHALTEN ? VERRINGERUNG ? VERWANDT ? ABHAENGIG ? Vermehrung ? WAND ? Art [Spezies] ? GEGENWART ? HINDERNIS ? GELOEST ? Auflösen ? INGENIEURWESEN ? Konzentrat ? MISCHUNG ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2008-10-01 - 2010-05-31
Accessed 1 times.