Dispersions of engineered nanoparticles in physiological liquids

Increasing production of nanomaterials makes the study of nanoparticles fate in the environment of immediate interest. Nanomaterials are known to radically change their properties when released into the environment. In this work, the ability of nanoparticles to form stable dispersions in physiological solutions has been demonstrated. The dispersions were prepared by mixing nanopowders of zinc (13.58 m2/g), copper (24.66 m2/g), aluminum oxides (54.75 m2/g), and zirconium dioxide (8.10 m2/g) with phosphate buffered saline, an isotonic solution of glucose and artificial lysosomal fluid. With the help of laser diffraction method and transmission electron microscopy it was shown that unstable suspensions (with the dispersoid size of 6...49 μm) and aggregative-stable lyosols (with the particles size of 20...300 nm) were formed in dispersions of nanoparticles in physiological media.</jats:p

Canalicular domain structure and function in matrix-free hepatic spheroids

International audienceLiver is pivotal in organism metabolism. This organ is receiving nutriments from the portal vein and then storing, metabolizing, distributing in the circulation or excreting excess and xenobiotics in bile. Liver architecture and hepatocyte polarization are crucial to achieve these functions. To study these mechanisms in details, relevant cell culture systems are required, which is not the case with standard 2D cell culture. Besides, primary hepatocytes rapidly de-differenciate making them inefficient in forming physiological system. Herein, we used an hepatoma-derived cell line to produce matrix-free hepatic spheroids and developed an integrated structural cell biology methodology by combining light sheet fluorescence microscopy and 3D electron microscopy to study their function and structure. Within these spheroids, hepatocytes polarize and organize to form bile canaliculi active for both organics and inorganics excretion. Besides, live imaging revealed the high dynamic of actin networks in basal membranes compared to their high stability in the apical pole that constitutes bile canaliculi. Finally, the first structure of active bile canaliculi was solved at nm resolution and showed the very high density of microvilli coming from all cells constituting the canaliculus. Therefore, this study is the first comprehensive and in-depth functional and structural study of bile canaliculi in a physiological-relevant context

Lessons from the combined use of synchrotron- and electron microscopy-based approaches for the analysis of silver nanoparticle fate in hepatocytes

sélectionnée sur résuméInternational audienc

Lessons from the combined use of synchrotron- and electron microscopy-based approaches for the analysis of silver nanoparticle fate in hepatocytes

sélectionnée sur résuméInternational audienc

Synchrotron-based imaging reveals silver ions trafficking within hepatocytes exposed to silver nanoparticles

Selected on abstractThe 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