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Synchrotron-based imaging reveals silver ions trafficking within hepatocytes exposed to silver nanoparticles
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Selected on abstract. The widespread use of silver nanoparticles (AgNP) in consumer goods raises concerns abouttheir toxicity to humans and their impact on environment [1]. AgNP toxicity in cells andanimals has been extensively studied and it has been shown that the toxicity depends uponthe release of Ag(I) ions from the NP[2,3]. Besides, Ag accumulates in liver following AgNPexposure [4]. In this context, we studied AgNP internalization and fate into hepatocytes. Wemade use of a synchrotron nanoprobe to visualize the subcellular distribution of silver. Thecombined use of X-ray fluorescence (XRF) microscopy on whole cells and electronmicroscopy allowed the discrimination between the nanoparticle form located insideendosomes and lysosomes and the ionic species that distribute throughout the cell [5].Besides, synchrotron X-ray absorption spectroscopy showed that Ag(I) recombines withsulphur in hepatocytes in the form of AgS2 and AgS3 complexes[5,6].More recently, we developed a nano-XRF method performed on cell sections (Figure 1) thatcan be correlated with electron microscopy to reveal Ag(I) species distribution at theorganelle level under long-term exposure to non-toxic concentration of AgNPs. We thusobserved Ag(I) species in different organelles including in the nucleus [7]. This approachwas also used on sections from 3D hepatic cell cultures that mimic liver architectureincluding bile canaliculi. XRF allowed to visualize Ag(I) excretion into these intercellularstructures. To get more insights into the fate and effects of AgNPs, these data werecompleted with 3D electron microscopy, STEM-EDX and physiology assays. The laterrevealed, for the first time, that Ag(I) species translocating into the nucleus can trigger anendocrine disruptor-like effect. Overall, synchrotron-based imaging was central in ourstudies that aim at understanding the fate of nanomaterials in cells and organisms.
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