Silver nanocube on gold microplate as a well-defined and highly active substrate for SERS detection

Strong enhancement and good reproducibility in Raman signals are two major requirements for a surface-enhanced Raman scattering (SERS) substrate to be used for sensitive detection of an analyte. Here we report a new type of SERS substrate that was fabricated by depositing a Ag nanocube (AgNC) on the surface of a Au microplate (AuMP). Owing to the strong and reproducible hot spots formed at corner sites of the AgNC in proximity with the AuMP surface, the new substrate showed high sensitivity and reproducibility. Using 1,4-benzenedithiol as a probe, the SERS enhancement factor of a typical "AgNC on AuMP" substrate could reach a level as high as 4.7×10⁷. In addition to the high sensitivity and reproducibility, the "AgNC on AuMP" substrate also displayed very good stability. Potential use of the "AgNC on AuMP" substrate was demonstrated by detecting crystal violet with high sensitivity.