title: Foliar exposure of the crop Lactuca sativa to silver nanoparticles: evidence for internalization and changes in Ag speciation.
abstract: The impact of engineered nanomaterials on plants, which act as a major point of entry of contaminants into trophic chains, is little documented. The foliar pathway is even less known than the soil-root pathway. However, significant inputs of nanoparticles (NPs) on plant foliage may be expected due to deposition of atmospheric particles or application of NP-containing pesticides. The uptake of Ag-NPs in the crop species Lactuca sativa after foliar exposure and their possible biotransformation and phytotoxic effects were studied. In addition to chemical analyses and ecotoxicological tests, micro X-ray fluorescence, micro X-ray absorption spectroscopy, time of flight secondary ion mass spectrometry and electron microscopy were used to localize and determine the speciation of Ag at sub-micrometer resolution. Although no sign of phytotoxicity was observed, Ag was effectively trapped on lettuce leaves and a thorough washing did not decrease Ag content significantly. We provide first evidence for the entrapment of Ag-NPs by the cuticle and penetration in the leaf tissue through stomata, for the diffusion of Ag in leaf tissues, and oxidation of Ag-NPs and complexation of Ag(+) by thiol-containing molecules. Such type of information is crucial for better assessing the risk associated to Ag-NP containing products.
authors.affiliation: ISTerre, Université Grenoble 1, CNRS, F-38041 Grenoble, France. Electronic address: camille.larue@rub.de.
authors.forename: Camille
authors.initials: C
authors.lastname: Larue
authors.affiliation: ESRF, Beamline ID21, Grenoble, France. Electronic address: castillo@esrf.fr.
authors.forename: Hiram
authors.initials: H
authors.lastname: Castillo-Michel
authors.affiliation: LASIR, UMR CNRS 8516, Université Lille 1, Bât C5, 59655 Villeneuve d'Ascq Cedex, France. Electronic address: sophie.sobanska@univ-lille1.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Sobanska
authors.affiliation: ISTerre, Université Grenoble 1, CNRS, F-38041 Grenoble, France. Electronic address: lauric.cecillon@irstea.fr.
authors.forename: Lauric
authors.initials: L
authors.lastname: Cécillon
authors.affiliation: ISTerre, Université Grenoble 1, CNRS, F-38041 Grenoble, France. Electronic address: sarah.bureau@ujf-grenoble.fr.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bureau
authors.affiliation: CEA/LITEN/DTNM/L2T, CEA Grenoble, 38054 Grenoble Cedex 9, France. Electronic address: veronique.barthes@cea.fr.
authors.forename: Véronique
authors.initials: V
authors.lastname: Barthès
authors.affiliation: LCABIE/IPREM-UMR 5254, Université de Pau et des Pays de l'Adour, 64053 Pau Cedex 9, France. Electronic address: laurent.ouerdane@univ-pau.fr.
authors.forename: Laurent
authors.initials: L
authors.lastname: Ouerdane
authors.affiliation: UMR E3 CEA-UJF/LAN, 38054 Grenoble Cedex 9, France. Electronic address: marie.carriere@cea.fr.
authors.forename: Marie
authors.initials: M
authors.lastname: Carrière
authors.affiliation: ISTerre, Université Grenoble 1, CNRS, F-38041 Grenoble, France. Electronic address: geraldine.sarret@ujf-grenoble.fr.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Sarret
mesh_terms: D018545:Lactuca / Q000737:chemistry* / Q000187:drug effects; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D018515:Plant Leaves / Q000737:chemistry* / Q000187:drug effects; D012834:Silver / Q000737:chemistry* / Q000633:toxicity
chemical_list: D012834:Silver
keywords: Ag nanoparticles; Biodistribution; Ecotoxicology; Plants; ToF-SIMS; micro-XAS