title: ZnO nanoparticles: synthesis, characterization, and ecotoxicological studies.
abstract: The potential ecotoxicity of nanosized zinc oxide (ZnO), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of ZnO nanoparticles, varied with the presence of protective agents such as tri-n-octylphosphine oxide (TOPO) and polyoxyethylene stearyl ether (Brij-76) used to control particle size and shape during the synthesis. In the case of Anabaena flos-aquae , the photosynthetic activity, after addition of ZnO, ZnO-TOPO, and ZnO-Brij-76, decreased progressively due to stress induced by the presence of the nanoparticles in the culture medium. After contact with ZnO-TOPO nanoparticles, this decrease was followed by cell death. On the other hand, after 10 days, a progressive increase of the photosynthetic activity was observed after contact with ZnO and ZnO-Brij-76 nanoparticles. In the case of Euglena gracilis , cell death was observed after contact with all nanoparticles. Transmission electron microscopy (TEM) analyses of ultrathin sections of microorganisms showed that polysaccharides produced by Anabaena flos-aquae avoid particle internalization after contact with ZnO and ZnO-Brij-76 nanoparticles. On the other hand, nanoparticle internalization was observed after contact with all nanoparticles in the presence of Euglena gracilis and also with ZnO-TOPO nanoparticles after contact with Anabaena flos-aquae .
authors.affiliation: Universite Paris Diderot (Paris 7), CNRS, UMR 7086, Interfaces, Traitements, Organisation et Dynamique des Systemes, 15 rue Jean de Baif, F-75205 Paris Cedex 13, France. roberta.brayner@univ-paris-diderot.fr
authors.forename: Roberta
authors.initials: R
authors.lastname: Brayner
authors.forename: Si Amar
authors.initials: SA
authors.lastname: Dahoumane
authors.forename: Claude
authors.initials: C
authors.lastname: Yéprémian
authors.forename: Chakib
authors.initials: C
authors.lastname: Djediat
authors.forename: Michaël
authors.initials: M
authors.lastname: Meyer
authors.forename: Alain
authors.initials: A
authors.lastname: Couté
authors.forename: Fernand
authors.initials: F
authors.lastname: Fiévet