1. Metal-Ligand Interface and Internal Structure of Ultrasmall Silver Nanoparticles (2 nm).
- Author
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Wetzel O, Hosseini S, Loza K, Heggen M, Prymak O, Bayer P, Beuck C, Schaller T, Niemeyer F, Weidenthaler C, and Epple M
- Subjects
- HeLa Cells, Humans, Ligands, Particle Size, Scattering, Small Angle, X-Ray Diffraction, Metal Nanoparticles toxicity, Silver
- Abstract
Ultrasmall silver nanoparticles were prepared by reduction with NaBH
4 and surface-terminated with glutathione (GSH). The particles had a solid core diameter of 2 nm as shown by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). NMR-DOSY gave a hydrodynamic diameter of 2 to 2.8 nm. X-ray photoelectron spectroscopy (XPS) showed that silver is bound to the thiol group of the central cysteine in glutathione under partial oxidation to silver(+I). In turn, the thiol group is deprotonated to thiolate. X-ray powder diffraction (XRD) together with Rietveld refinement confirmed a twinned (polycrystalline) fcc structure of ultrasmall silver nanoparticles with a lattice compression of about 0.9% compared to bulk silver metal. By NMR spectroscopy, the interaction between the glutathione ligand and the silver surface was analyzed, also with13 C-labeled glutathione. The adsorbed glutathione is fully intact and binds to the silver surface via cysteine. In situ H NMR spectroscopy up to 85 °C in dispersion showed that the glutathione ligand did not detach from the surface of the silver nanoparticle, i.e. the silver-sulfur bond is remarkably strong. The ultrasmall nanoparticles had a higher cytotoxicity than bigger particles in1 H NMR spectroscopy up to 85 °C in dispersion showed that the glutathione ligand did not detach from the surface of the silver nanoparticle, i.e. the silver-sulfur bond is remarkably strong. The ultrasmall nanoparticles had a higher cytotoxicity than bigger particles in in vitro cell culture with HeLa cells with a cytotoxic concentration of about 1 μg mL-1 after 24 h incubation. The overall stoichiometry of the nanoparticles was about Ag∼250 GSH∼155 .- Published
- 2021
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