Synthesis, Characterization, and Bioconjugation of Fluorescent Gold Nanoclusters toward Biological Labeling Applications

Abstract

Synthesis of ultrasmall water-soluble fluorescent gold nanoclusters is reported. The clusters have a decent quantum yield, high colloidal stability, and can be readily conjugated with biological molecules. Specific staining of cells and nonspecific uptake by living cells is demonstrated.

Functionalized Au22 Clusters: Synthesis, Characterization, and Patterning

“…Thus, the lower mass number features with successive Au losses are attributed to fragmentation and laser-induced dissociation of the clusters. The slight enhancement in the relative intensity of Au 18 may be attributed to the increased stability of this core in comparison to those of Au 21 , Au 20 , and Au 19 . The MS spectrum shows a peak at m/z 4878 (in the higher mass region, the spectrum is multiplied by a factor of 9), assigned to Au 22 S 17 ( Figure 2A).…”

“…It is important to note that there is no higher mass number feature of significant intensity above m/z 4878. The spectrum is characteristic in the sense that below this peak all of the lower clusters of Au 21 , Au 20 , etc., are observed. Laser desorption ionization of gold thiolate clusters and nanoparticles results in C-S bond cleavage (5,61,62) and so the peak at m/z 4878 can be attributed to Au 22 L 17 , where L is a thiolate.…”

“…Tsukuda et al synthesized a series of GSH-protected clusters and determined their chemical composition by ESI-MS (36). These clusters are Au 10 (SG) 10 , Au 15 (SG) 13 , Au 18 (SG) 14 , Au 22 (SG) 16 , Au 22 (SG) 17 , Au 25 (SG) 18 , Au 29 (SG) 20 , Au 33 (SG) 22 , and Au 39 (SG) 24 . All of these nine clusters have good stability.…”

Reversible Size Control of Silver Nanoclusters via Ligand-Exchange

“…[11][12][13] The emerging opportunities in catalysis, 14 energy, 15,16 environment, 17 and biology 18 enabled by the small size and often precise nature of these materials has spurred researchers to explore a multitude of synthetic routes to attain them including borohydride and gaseous reduction; 19,20 26 ; and templated growth in proteins, 27 polymers, 24 and gel cavities. 26 Each of these methods produces size-specific NCs.…”

Gold nanoclusters as novel optical probes for in vitro and in vivo fluorescence imaging

“…Such large two-photon absorption cross-sections make AuNCs efficient absorbers for multi-photon biological imaging. Furthermore, AuNCs have been observed to possess better photostability than organic dyes (Polavarapu et al 2011;Lin et al 2009). For instance, lipoic acid-coated AuNCs exhibited a much slower photobleaching rate than organic fluorophores such as fluorescein and rhodamine 6G ).…”