Au–Ag–Au double shell nanoparticles-based localized surface plasmon resonance and surface-enhanced Raman scattering biosensor for sensitive detection of 2-mercapto-1-methylimidazole

In this paper, Au–Ag–Au double shell nanoparticles were prepared based on the reduction of the metal salts HAuCl4 and AgNO3 at the surface of seed particles. Due to the synergistic effect between Au and Ag, the hybrid nanoparticles are particularly stable and show excellent performances on the detection of 2-mercapto-1-methylimidazole (methimazole). The binding of target molecule at the surface of Au–Ag–Au double shell nanoparticles was demonstrated based on both localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS) spectra. The LSPR intensity is directly proportional to the methimazole concentration in the range of 0.10–3.00×10−7 mol L−1. The SERS spectrum can be applied in identification of methimazole molecule. The LSPR coupled with SERS based on the Au–Ag–Au double shell nanoparticles would be very attractive for the quantitative determination and qualitative analysis of the analytes in medicines.