Fig. 1

Structure and characterization of the AuNCs. A UV-Vis absorption spectrum of solution during preparation; insets indicate the corresponding color changes. B FTIR spectrometry of synthesized AuNCs and ligand (MHA). C XPS survey spectrum of AuNCs, and D the corresponding high-resolution XPS spectrum of Au 4 f. E HR-TEM of AuNCs. F Size distribution of the AuNCs calculated using HR-TEM.