Fig. 1: Characterization and functionalization of Au-GSH clusters.

a Crystallographic representation of Au₂₅ cluster structure. Color codes of the elements: Au (0) in the core: yellow, Au (I) in the staple motif: orange, S in the staple motif: green. The structure was prepared using UCSF Chimera program (version 1.12) based on crystal structure data published in Reference 46. b Postfunctionalization of Au-GSH cluster and schematic representation of Au-PC conjugate structure. For clarity, only one staple motif and adjacent gold core atoms are shown. For simplicity, the conjugation of PC ligand to glycine carboxylic group is omitted and it is only shown with γ-glutamate carboxylic functional group of GSH. c UV-vis absorption and fluorescence spectra of Au-GSH cluster in aqueous phase. d CryoEM micrograph of Au-GSH clusters with an average size of 1.64 nm ± 0.24 nm (n = 3). e Descriptive statistical analyses of particle size distribution of Au-GSH clusters obtained from cryoEM micrograph. f ESI-MS spectrum of the Au-GSH cluster in negative ion mode from m/z 1000 to 3000: several negatively charged species of 5–8 were identified and the remaining peaks were small and attributed to impurity clusters/species. g ESI-MS spectra of major peaks 5–8 with estimated sodium adducts were assigned to a common [Au₂₅(GS)₁₈ + xNa-xH-zH]^z formula. a.u.: arbitrary units. Source data are provided in Source Data file.