Fig. 1. (A) Schematic illustration of the synthesis of Au@IS@AgNPs. (B and C) TEM images of the Au@4-Mpy@AgNPs. (D) STEM images of the Au@4-Mpy@AgNPs using the Ag Lα1, Au Lα1 and S Kα1 signals. (E) UV-Vis spectra of the AuNPs and Au@4-Mpy@AgNPs. (F) Raman spectra of the AuNPs and Au@4-Mpy@AgNPs.