SERS detection of 4-Aminobenzenethiol based on triangular Au-AuAg hierarchical-multishell nanostructure

The surface-enhanced Raman signals of 4-Aminobenzenethiol (4-ABT) adsorbed on the surface of triangular Au-AuAg hierarchical-multishell nanostructure have been investigated. Here, the approach to produce core-cavity-shell sandwich nanostructures presented as Au-AuAg is the same as preparing metal nanoparticles with hollow morphology, in which the galvanic replacement reaction takes place between silver and chloroauric acid. In this paper, we directly mix 4-ABT with gold nanoparticles and drop it on glass slides to study the effect of nanoparticles on signal enhancement of Raman spectrum, avoiding the cumbersome process of preparing metal-molecular-metal three-layer structure as reported. A significant increase in the SERS intensity of b₂ mode around 1140 cm⁻¹ was observed, which could quantify the concentration of 4-ABT indirectly. In a certain range, the Raman intensity gradually increases with the increasing intermediate gap, which has a strong relationship with dipole plasmon hybridization of core-dielectric-shell sandwich nanostructure. Moreover, Raman spectrum results show that the Au-AuAg substrate can produce signal intensity about 3.8 × 10² times stronger than that of 4-ABT alone and the detection limit was as low as 0.1 μM in solution.