Hydrophilic gold and silver nanoparticles stabilized with 2-diethylaminoethanethiol hydrochloride (DEA) have been prepared and characterized. AuNPs-DEA and AgNPs-DEA with mean diameter below 10 nm have been characterized by means of dynamic light scattering and fieldemission scanning electron microscopy techniques. Nuclear magnetic resonance (NMR) studies allowed to assess translational mobility, aggregation equilibrium in function of pH variations and presence of chemisorbed and physisorbed thiol molecules; in particular ethyl groups on DEA ligands are free to rotate, suggesting a rather loose packing of the thiols on the nanoparticle surface. NMR results were compared with X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray absorption spectroscopy. The complementary information acquired allowed to obtain information on the interaction at the interface between the organic thiol ligand and metal nanoparticles (NPs) at atomic level as well as on the molecular structure. The influence of the thickness of the functionalizing layer on the stability of NPs has been studied and opened new insight on the local structure surrounding the NP

Gold nanoparticles (AuNPs) have been extensively used in biological applications because of their high\ud biocompatibility, ease of characterization and the extensive knowledge of their surface chemistry. These\ud features make AuNPs readily exploitable for drug delivery and novel diagnostic and therapeutic\ud approaches. In a previous work, we showed that small size (5–10 nm) AuNPs functionalized by sodium\ud 3-mercapto-1-propanesulfonate (3MPS) can be efficiently loaded with the glucocorticoid drug\ud dexamethasone (DXM) and are stable in water and PBS. In the present study, we further analysed the\ud stability and the drug release kinetics of DXM-loaded AuNPs functionalized by sodium 3mercaptopropane\ud sulfonate (AuNP-3MPS/DXM) and their unconjugated counterparts (AuNP-3MPS) in\ud different biological media. Moreover, we evaluated AuNP-3MPS cyto-compatibility on two mammalian\ud cell lines and tested their specific activity as drug carriers on DXM-sensitive murine and human tumor\ud cells. The colloidal stability of AuNP-3MPS/DXM was significantly increased in all tested culture media,\ud compared with the unconjugated AuNP-3MPS and both AuNP-3MPS formulations which proved nontoxic\ud to biological systems in vitro. Most importantly, we showed that AuNP-3MPS/DXM continuously\ud release bioactive DXM molecules that efficiently induce cell proliferation arrest and apoptotic cell death\ud on a human lymphoma cell line and upregulation of the DXM-inducible programmed cell death-1 (PD-1)\ud molecule on activated mouse T lymphocytes. These data confirm that the AuNP-3MPS/DXM conjugate\ud is a promising system for drug delivery and open interesting perspectives for future in vivo applications

Small gold nanoparticles capped with 4trimethylsilylethynyl-1-acetylthiobenzene (SEB) were prepared with spherical shape and different mean sizes (5−8 nm). The functionalized gold nanoparticles (AuNPs-SEB) were deposited onto TiO 2 substrates, and the interaction at the molecule−gold interface, the molecular layer thickness, and the ligand organization on the surface of Au nanospheres were investigated by means of synchrotron radiation induced X-ray photoelectron spectroscopy (SR-XPS) and angular dependent near edge X-ray absorption spectroscopy (NEXAFS) at the C K-edge. In order to obtain better insight into the molecular shell features, the same measurements were also carried out on a self-assembling monolayer (SAM) of SEB anchored on a "flat" gold surface (Au/Si(111) wafer). The comparison between angular dependent NEXAFS spectra collected on the self-assembling monolayer and AuNPs-SEB allowed for successfully probing the molecular arrangement of SEB molecules on the gold nanospheres surface. Furthermore, DFT calculations on the free SEB molecule as well as bonded to a small cluster of gold atoms were developed. The comparison with experimental results allowed better understanding of the spectroscopic signatures in the experimental absorption spectra and rationalization of the molecular organization in the SAM, NPs having a thin molecular shell, and NPs covered by a thick layer of ligands.

By causing a decrease in cAMP concentration, zinc directly promotes ion absorption and substantially reduces CT-induced, but not E. coli ST-induced, ion secretion.

Advances in element speciation analysis of biomedical samples using synchrotron-based techniques. Trends in Analytical Chemistry, Elsevier, 2018, 104, pp. Highlights principle of direct element speciation with synchrotron X-ray absorption spectroscopy (XAS)  experimental modalities for bulk-and micro-XAS speciation and their limitations  review (2012-2017) of XAS in pharmacology, metals and nanoparticles toxicology, physiopathology  future directions and developments of XAS speciation for biomedical research AbstractSynchrotron-radiation X-ray absorption spectroscopy (XAS) is a direct method for speciation analysis with atomic resolution, providing information about the local chemical environment of the probed element. This article gives an overview of the basic principles of XAS and its application to element speciation in biomedical research. The basic principle and experimental modalities of XAS are introduced, followed by a discussion of both its limitations, such as beam damage or detection limits, and practical advices to improve experiments. An updated review of biomedical studies involving XAS published over the last 5 years is then provided, paying special attention to metal-based drug biotransformation, metal and nanoparticle toxicology, and element speciation in cancer, neurological, and general pathophysiology. Finally, trends and future developments such as hyphenated methods, in situ correlative imaging and speciation, in vivo X-ray Absorption Near Edge Spectroscopy (XANES), full-field XANES, and X-ray Free Electron Laser (XFEL) XAS are presented.