Water-Soluble, Isolable Gold Clusters Protected by Tiopronin and Coenzyme A Monolayers

Abstract

Isolable, water-soluble gold clusters protected by monolayers of tiopronin (tiopronin−MPCs) or coenzyme A (CoA−MPCs) were synthesized by a procedure of comparable simplicity to the Brust synthesis for alkanethiolate monolayer-protected gold clusters. High-resolution transmission electron microscopy shows that, like their alkanethiolate−MPC counterparts, the average core diameters of tiopronin−MPCs can be systematically controlled by varying the tiopronin:Au mole ratio employed in the reaction. The UV−vis spectra of tiopronin−MPCs exhibit pH and core size dependency of the surface plasmon band position and intensity, respectively. Thermogravimetric analysis of the tiopronin−MPCs gave average numbers of tiopronin ligands per cluster; for example, tiopronin−MPCs with an average core size of 1.8 nm (∼Au201) are protected with an average of 85 tiopronin ligands. 1H NMR reveals a size-dependent evolution of spectral features interpreted as reflecting differences in attachment sites (terrace, defects) and/or restriction in ligand mobility. Infrared spectroscopy reveals strong hydrogen bonding in the monolayer and provides evidence for intercluster association, and acid/base titrations produce pK A values similar to the free ligand in the presence of a charge-screening supporting electrolyte, but higher in its absence. The same analytical methods were also applied to CoA-MPCs.

Capillary electrophoresis coupled with inductively coupled mass spectrometry as an alternative to cloud point extraction based methods for rapid quantification of silver ions and surface coated silver nanoparticles

“…Tiopronin, a thio-containing compound, was used for this purpose. It has been used to treat cystinuria and rheumatoid arthritis and as capping ligand for the synthesis of gold nanocluster [24,25]. We found that adding tiopronin to concentration of 1 mM in BGE was optimal for the analysis.…”

Development of a novel gene delivery scaffold utilizing colloidal gold–polyethylenimine conjugates for DNA condensation

“…Colloidal gold synthesis is well understood, and there are a variety of known synthetic preparation methods based in both aqueous and organic solvent systems that span a range of sizes from a few nanometers up to about a tenth of a micron. [11][12][13] In addition, colloidal gold has a history of use in biological and medical applications with no known inherent cytotoxicity. 10,14,15 Colloidal gold's high electron density allows its direct imaging via electron microscopy and its unique surface plasmon resonance properties provide a convenient handle on the aggregation state of the colloid.…”

“…10,14 Colloidal gold reacts selectively and covalently with thiol or disulfide-containing reagents, allowing a straightforward route to covalent ligand-gold conjugation for surface chemistry manipulation or targeting purposes. 12,13,16,17 Finally, it may also be possible to display targeting groups on the surface of the colloidal gold particles by simple direct physical adsorption. 15 Many investigators of nonviral gene scaffolds have used the charge ratio, or ratio of cations to anions in a formulation, to quantify the amount of polycationic carrier relative to the amount of DNA in their complexes.…”

Electronic structure, magnetic properties, and microstructural analysis of thiol-functionalized Au nanoparticles: role of chemical and structural parameters in the ferromagnetic behaviour

“…Simard et al (2000) developed a synthesis method that we have used to produce gold NPs simultaneously capped with both octanethiol and thiolated undecanoic acid molecules (sample labelled Au-SC 8 /SC 11 COOH). Finally, following the synthesis method presented by Templeton et al (1999), we have synthesized water soluble gold NPs capped with tiopronin (Au-ST), which is a synthetic thiol-containing biomolecule.…”