Synthesis of Peptide Mediated Au Core-Ag Shell Nanoparticles as Surface-Enhanced Raman Scattering Labels

As the fundamental understanding of metal-light interactions gains solid grounds, further research has been devoted to construct novel structures that take full advantage of such unique interactions, which is called plasmonics. In this report, the preparation of Au-Ag core-shell structures obtained by coating the Au surface with peptide and Raman reporter molecule and depositing an Ag layer on it is reported. The prepared Au-Ag NPs are tested for their surface-enhanced Raman scattering (SERS) performance. The negatively charged peptides with three different lengths, which are 3 (P1), 15 (P2), and 21 (P3) amino acid long, were chemically attached to 13 nm AuNPs along with Raman reporter molecule, carboxytetramethylrhodamine, and these modified AuNPs were coated with three different shell thickness of Ag metal. The prepared Au-Ag NPs were tested for their SERS performance and found that the Au-Ag NPs prepared with P2 and thickest shell performs best as SERS label.