Gold Cluster Crystals

Abstract

<jats:p>Gold clusters are gold compounds with a core of gold atoms and organic groups covalently bound to the surface gold atoms. An example is undecagold, Au<jats:sub>11</jats:sub>(P(C<jats:sub>6</jats:sub>H<jats:sub>5</jats:sub>)<jats:sub>3</jats:sub>)<jats:sub>7</jats:sub>, whose structure was solved by x-ray crystallography using 3-dimensional crystals. These differ from colloidal gold, which are suspensions of metal particles, usually formed by metal ion reduction; although the particles may be approximately the same size, they vary due to the statistical process of formation. Gold clusters are compounds with a definite formula, and should all be perfectly identical. However, it is known that there is a family of stable gold cluster compounds, such as Au<jats:sub>6</jats:sub>, Au<jats:sub>11</jats:sub>, Au<jats:sub>13</jats:sub>, AU<jats:sub>55</jats:sub>, Au<jats:sub>67</jats:sub>, etc. In a given preparation of gold clusters, there is usually some mixture of these, thus leading to some size variation. Methods such as gel filtration column chromatography and ultrafiltration can be used to separate most of these species, so that relatively pure preparations may be achieved.</jats:p>

Biocompatible gold nanoclusters: synthetic strategies and biomedical prospects

“…The amino group could be functionalized with a maleimide to promote the formation of a covalent bond between the AuNCs-ligand and a thiol-containing protein in aqueous conditions. In the early '90s, Hainfeld et al developed and then commercialized Au 67 -phosphine maleimide conjugate named Nanogoldmaleimide [28]. Another type of AuNCs capable of reacting towards the amino-groups of proteins in water (Nanogold-NHS ester) was also made available [28,29].…”

“…In the early '90s, Hainfeld et al developed and then commercialized Au 67 -phosphine maleimide conjugate named Nanogoldmaleimide [28]. Another type of AuNCs capable of reacting towards the amino-groups of proteins in water (Nanogold-NHS ester) was also made available [28,29].…”

“…In this context, the team of Hainfeld prepared a dual system affording both fluorescence and opacity to EM. The group discovered that the AuNCs quenches the fluorescence of fluorescein when the fluorophore was directly attached to the AuNCs-bound ligands phosphine [28]. However, the quenching of fluorescence decreased by increasing the distance between the gold and fluorophore.…”