Electrochemiluminescence of Glutathione‐Stabilized Au Nanoclusters Fractionated by Gel Electrophoresis in Water

Abstract

We report the electrochemiluminescence (ECL) of water‐soluble individual Au nanoclusters (Au NCs) fractionated by polyacrylamide gel electrophoresis of Au NCs synthesized using glutathione. The individual Au NCs demonstrated unique and significant differences in ECL. Interestingly, they exhibited near‐infrared (near‐IR) ECL that became dominant when the ratio of Au(I) to Au(0) decreased in the individual Au NCs. This indicated that the oxidation states of Au NCs primarily affected the ECL wavelengths of the clusters because the Au(0)‐glutathionate motif in the Au NCs was responsible for the near‐IR ECL emission.

Post-Synthesis Modification of Photoluminescent and Electrochemiluminescent Au Nanoclusters with Dopamine

“…Their ECL spectra were obtained at a potential of 1.3 V in the presence of TEA as an anodic co-reactant for oxidative-reduction ECL reactions. In agreement with previous studies [ 30 , 31 ], the ECL spectra show a strong NIR ECL peak at ca . 800 nm with a shoulder peak at ca .…”

“…790 nm upon excitation at λ ex = 365 nm ((i) in Figure 5a). The orange PL of the as-synthesized Au NCs at 610 nm was in agreement with the PL emission observed for the Au NCs synthesized using GSH in previous reports, wherein the PL was attributed to AIE of the Au(I)-SG motifs on their shell surface [18,30,31]. The PL emission could be ascribed to ligand-to-metal charge transfer (LMCT) or ligand-to-metal-metal charge transfer (LMMCT) from the sulfur atom to the Au atoms in the dense Au(I)-SG shell on the cluster surface, and subsequent radiative relaxation [18,41].…”

“…In agreement with our recent studies, the as-synthesized Au NCs exhibited a strong NIR ECL peak with a shoulder peak in the visible region, while the nanoclusters emitted a strong PL peak primarily in the visible region [30,31]. We ascribed the NIR and visible emission peaks of the nanoclusters to the Au(0)-SG motif in their metallic core and the Au(I)-SG motif on their shell surface, respectively [30,31]. The as-synthesized Au NCs were subjected to the post-synthesis functionalization for surface coupling of dopamine on the cluster shell.…”

“…The Au NCs were synthesized using GSH acting as a thiolate ligand, similar to previous reports [ 18 , 30 ]. In agreement with our recent studies, the as-synthesized Au NCs exhibited a strong NIR ECL peak with a shoulder peak in the visible region, while the nanoclusters emitted a strong PL peak primarily in the visible region [ 30 , 31 ]. We ascribed the NIR and visible emission peaks of the nanoclusters to the Au(0)-SG motif in their metallic core and the Au(I)-SG motif on their shell surface, respectively [ 30 , 31 ].…”

“…620 nm. Because the shoulder peak wavelength matched the clusters' orange PL, we attributed the shoulder ECL emission to the Au(I)-SG motifs on the NC surface, as reported in the previous findings [30,31]. Similarly, the NIR ECL emission was ascribed to the Au(0)-SG motifs, responsible for the PL of the clusters at 790 nm, in the metallic core of the Au NCs [30,31].…”