posted on 2021-11-05, 22:13authored byMaryam Alyari, Robert W. J. Scott
An
improved and simple synthetic method for producing stable narrow-sized
glycine-cystamine (Gly-CSA)-functionalized Au nanoclusters (NCs) from
protected Fmoc-glycine-cystamine (Fmoc-Gly-CSA)-functionalized Au
NCs is demonstrated in this study. The NC size and size distribution
can be controlled directly as a function of reducing agent concentration
with the formation of smaller NC core diameters at higher concentrations
of NaBH4. Furthermore, when using 0.30 M NaBH4, three UV–vis absorption peaks at 690, 440, and 390 nm were
seen, which are consistent with the formation of Fmoc-Gly-CSA-functionalized
Au25L18 NCs. After deprotection of the Gly-CSA-functionalized
Au NCs, the reactivity of the primary amine groups was investigated.
Methyl acrylate-glycine-cystamine (MA-Gly-CSA)-functionalized Au NCs
with terminal acetyl groups were formed via the Michael addition reaction
of terminal amine groups with methyl acrylate. This reaction resulted
in the formation of ester-terminated Au NCs including atom-precise
MA-Gly-CSA Au25(SR)18 NCs. The functionalization
of the ligand was confirmed by 1H NMR and UV–vis
spectra, and TEM images of MA-Gly-CSA- and Gly-CSA-functionalized
Au NCs showed that the size of the NCs remained unchanged after the
reaction. With controllable NC size and facile functionalization of
the Gly-CSA-functionalized Au NCs, these clusters have promising potential
as scaffolds for biomedical applications.