Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering Responses of Au@Ag Core–Shell Nanorods with Different Thickness of Ag Shell

Abstract

The properties of the localized surface plasmon resonance (LSPR) and the surface enhanced Raman scattering (SERS) of the core-shell bimetallic nanostructures, that is the monodisperse Au@Ag core-shell nanorods with different thickness of Ag shell, are theoretically and experimental researched. The UV-vis-NIR absorption spectra of the Au@Ag core-shell nanorods are measured and displayed their blue-shifts of the longitudinal plasmon resonance peaks with increasing of Ag concentrations in the colloidal solution. And the absorption spectra of the Au@Ag core-shell nanorods are simulated by the Finite Element Method (FEM), which are in agreement with the experimental measurements and reveal their LSPR mechanism as the varying structures. In addition, Rhodamine 6G, as a Raman reporter molecule, is used to investigate SERS of gold nanorods and Au@Ag core-shell nanorods. It is found that Au@Ag core-shell nanorods have better SERS responses, comparing with those of Au nanorods, and their SERS intensities are increased with the increases of the Ag shell thickness, which demonstrate that the chemisorptive bond effect and the morphology of the nanoparticle play key roles to the SERS signals. It is significant to design the biosensor based on the properties of Au@Ag core-shell nanorods.

Au@Ag core/shell cuboids and dumbbells: Optical properties and SERS response

“…In general, increasing the Ag shell thickness improves SERS performance [28,36]. Controlling the thickness and preferred facets of the overgrown Ag shell determines the final shape of nanoparticles and their plasmonic properties [37].…”

Sythesis, Modification, and Biosensing Characteristics of Au2S/AuAgS‐Coated Gold Nanorods

“…As shown in Table 1, the GNRs and Au 2 S/AuAgS/GNRs coated with CTAB are positively charged during the preparation of GNRs. However, after coating MUA layer on the surface of Au 2 S/AuAgS/GNRs, the zeta-potential increases 6.6 mV more than that of Au 2 S/AuAgS/GNRs due to the thiol group attached to the nanorods and the formation of layers of alkanethiol molecules [31,32]. Meanwhile, the zeta-potential of PSS suffers an extreme change from +30.6 mV to −44.3 mV, which was from the interaction between the positive charge of CTAB and the negative charge of PSS [33,34].…”

Novel Approach to Surface Plasmon Resonance: A Third Dimension in Data Interpretation Through Surface Roughness Changes

“…Shortly after, this phenomena named Surface Plasmon Resonance (SPR) was used in technological applications as a versatile technique for gas sensors [3], in the study of optical properties of metals [4], or as a microscopy technique [5]. Recently, the SPR technique was integrated into a powerful biosensing system [6][7][8].…”