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Nanoscale. 2016 Sep 29;8(38):17012-17021.

Visualization, quantification and coordination of Ag+ ions released from silver nanoparticles in hepatocytes.

Author information

1
CNRS, Laboratoire de Chimie et Biologie des Métaux (LCBM) UMR 5249 CNRS-CEA-UGA, F-38054 Grenoble, France and CEA, LCBM, F-38054 Grenoble, France and Université Grenoble Alpes, LCBM, F-38054 Grenoble, France. giulia.veronesi@esrf.fr aurelien.deniaud@cea.fr isabelle.michaud-soret@cea.fr and ESRF, The European Synchrotron, 71, Avenue des Martyrs, 38043 Grenoble, France.
2
CNRS, Laboratoire de Chimie et Biologie des Métaux (LCBM) UMR 5249 CNRS-CEA-UGA, F-38054 Grenoble, France and CEA, LCBM, F-38054 Grenoble, France and Université Grenoble Alpes, LCBM, F-38054 Grenoble, France. giulia.veronesi@esrf.fr aurelien.deniaud@cea.fr isabelle.michaud-soret@cea.fr.
3
INAC-MEM, Université Grenoble Alpes, Grenoble, France and CEA, INAC-MEM, Grenoble, France.
4
ESRF, The European Synchrotron, 71, Avenue des Martyrs, 38043 Grenoble, France.
5
Université Grenoble Alpes, INAC-SCIB, F-38054 Grenoble, France and CEA, INAC-SyMMES, F-38054 Grenoble, France.
6
BM30B/FAME beamline, ESRF, F-38043 Grenoble cedex 9, France and Observatoire des Sciences de l'Univers de Grenoble, UMS 832 CNRS Université Joseph Fourier, F-38041 Grenoble, France.

Abstract

Silver nanoparticles (AgNPs) can enter eukaryotic cells and exert toxic effects, most probably as a consequence of the release of Ag+ ions. Due to the elusive nature of Ag+ ionic species, quantitative information concerning AgNP intracellular dissolution is missing. By using a synchrotron nanoprobe, silver is visualized and quantified in hepatocytes (HepG2) exposed to AgNPs; the synergistic use of electron microscopy allows for the discrimination between nanoparticular and ionic forms of silver within a single cell. AgNPs are located in endocytosis vesicles, while the visualized Ag+ ions diffuse in the cell. The averaged NP dissolution rates, measured by X-ray absorption spectroscopy, highlight the faster dissolution of citrate-coated AgNPs with respect to the less toxic PVP-coated AgNPs; these results are confirmed at the single-cell level. The released Ag+ ions recombine with thiol-bearing biomolecules: the Ag-S distances measured in cellulo, and the quantitative evaluation of gene expression, provide independent evidence of the involvement of glutathione and metallothioneins in Ag+ binding. The combined use of cutting-edge imaging techniques, atomic spectroscopy and molecular biology brings insight into the fate of AgNPs in hepatocytes, and more generally into the physicochemical transformations of metallic nanoparticles in biological environments and the resulting disruption of metal homeostasis.

PMID:
27722394
DOI:
10.1039/c6nr04381j
[Indexed for MEDLINE]

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