Unique Ultrafast Visible Luminescence in Monolayer-Protected Au₂₅ Clusters

Abstract

TEM images of MPC samples were obtained with a JEOL transmission electron microscope (JEM-1230). MPC samples were prepared by dipping a Formvar/carbon-coated copper grid (400C-FC, EMS) in 1 mg/mL MPC in CH 2 Cl 2 for the hexanethiolate MPC and water in the case of the glutathione MPC and citrate nanoparticle. Three typical regions of each sample were imaged at 600 K magnification and 200 K magnification for the Au-Citrate sample. Core-size histograms were read from digitized photographic images using ImageJ software [http://rsb.info.nih.gov/ij/].

On the selection and design of proteins and peptide derivatives for the production of photoluminescent, red-emitting gold quantum clusters

“…It has been confirmed that redemitting Au 25 clusters consist of a 13-atom core, surrounded by 12 peripheral gold atoms forming an Au I -S semi ring [38][39][40]. The existence of the latter requires a minimum number of sulfur-containing residues per gold cluster [39,41]. These considerations suggest the existence of a critical initial molar ratio of the protein and the gold precursor necessary for cluster formation.…”

“…It has been reported that the former can protect clusters and form Au I complexes [28,[37][38][39][40][41], while the latter can produce Au 0 [14,26,29]. We designed our mixtures based on the assumption that tyrosine and cysteine play the key role in the process [14], but also investigated the possibility of synergic effects with tryptophan and methionine.…”

The excited state dynamics of protein-encapsulated Au nanoclusters

“…At present, several models have been proposed to explain the origin of the two PL band of Au nanoclusters, including the solid state model and molecular model [16,19,22]. Based on the previous models and our results, a model for the electronic structure of Au nanoclusters is proposed and shown in Figure 7.…”

“…In previous PL studies, a red or near-infrared (NIR) emission, centered from 610 to 920 nm, was observed for Au 38 [15], Au-BSA [14], Au 55 [16], Au(I)-thiolate complex [17], and Au 25 (SG) 18 nanoclusters [5,18]. This red band was suggested to be associated with the ligand [16,19]. Compared to the red/NIR emission, there have been relatively few reports concerning the blue emission of Au nanoclusters.…”

Luminescent gold nanoclusters as biocompatible probes for optical imaging and theranostics

“…[34] Furthermore, luminescence enhancement was proportional to the electron withdrawing capability of the inserted ligand and to the charge shift of the cluster core toward more positive values (figure 5). [24,34,[117][118][119] Although the interaction between ligands and GNCs is not completely clarified, observed luminescent lifetimes in the range of microseconds [24] suggested the generation of triplet states populated through ISC. Non radiative transition is favourite by the strong spin-orbit coupling due to heavy atom effect.…”