Fig. 1: Characterization of synthesized [Au₂₅(Cys)₁₈].

a UV–Vis spectrum of [Au₂₅(Cys)₁₈] solution (inset shows the picture and TEM image of [Au₂₅(Cys)₁₈] solution). b, c ESI-mass spectra of [Au₂₅(Cys)₁₈]. d Comparison between theoretical and experimental isotope pattern of #1 peak.