By a News Reporter-Staff News Editor at Science Letter -- Researchers detail new data in Nanoparticles. According to news reporting originating in Berlin, Germany, by NewsRx journalists, research stated, "Unprotected ('naked') gold nanoparticles with high monodispersity (< d>, 5.5 +/- 0.5 nm) were obtained in a facile and single-step microwave assisted hydrolytic decomposition of the molecular precursor [NMe4][Au(CF3)(2)]. Given their chloride free surface chemistry, the as-obtained gold nanoparticles were in situ functionalized with mono-, di-, and trivalent thiolated PEG ligands in order to study the influence of multivalent character of the ligands on the stability of the colloidal solutions For this purpose, a novel tridentate ligand was synthesized and the previously reported syntheses of mono- and divalent thiol ligands were improved."
The news reporters obtained a quote from the research from Free University, "Owing to the pristine character of the Au nanoparticles no ligand exchange was required, and the colloidal and chemical stability of the mono- and multivalent functionalized particles purely depended on the ligating ability of the thiolated groups. In situ-functionalized Au nanoparticles showed a strikingly (2 orders of magnitude higher) improved stability against small nucleophiles such as sodium cyanide compared to gold nanoparticles coated with citrate ligands and functionalized via a ligand-exchange reaction. The monovalent thiol PEG ligand produced most stable colloids against cyanide, which is explained by a strongly increased numerical ligand-density on the surface. Gold colloids stabilized by di- and trivalent ligands exhibited high stability in aqueous solutions with high NaCl concentrations (2 M) in contrast to those functionalized with the monovalent PEG ligand, which were only temporally stable in dilute NaCl solutions."
According to the news reporters, the research concluded: "The beneficial effect of the multivalence of the ligands was further demonstrated by the incorporation of an additional chelating ligand (dithiothreitol) to the colloidal dispersions."
For more information on this research see: Improved Stability of "Naked" Gold Nanoparticles Enabled by in Situ Coating with Mono and Multivalent Thiol PEG Ligands. Langmuir, 2013;29(36):11217-11226. Langmuir can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Langmuir - www.pubs.acs.org/journal/langd5)
Our news correspondents report that additional information may be obtained by contacting D. Zopes, Free University of Berlin, Inst Chem & Biochem Phys & Theoret Chem, D-14195 Berlin, Germany. Additional authors for this research include B. Stein, S. Mathur and C. Graf (see also Nanoparticles).
Keywords for this news article include: Berlin, Europe, Germany, Nanotechnology, Gold Nanoparticles, Emerging Technologies
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