Surface-Enhanced Raman Scattering Quantitative Analysis of Ethanol Drop-Coating Silver Nanocubes on Gold Film

Surface-enhanced Raman scattering (SERS) has been a sensitive tool for the accurate detection and analysis of a wide range of molecules. In the present study, a simple and repeatable approach is developed for the fabrication of a silver nanocubes/polyelectrolyte/gold film (Ag nanocubes/PE/Au film) sandwich structure as SERS substrate. An ethanol-water mixture, instead of pure water, is used as solvent to reduce the coffee ring effect by the drop coating deposition method, such that Ag nanocubes are distributed evenly on the gold film surface with polyelectrolyte as the middle layer. In 15 repeated measurements of a 10^-7 M rhodamine 6G solution, the intensity of the Raman peak at 609 cm^-1 exhibits a relative standard deviation less than 20%. Significantly, the sandwich substrate exhibits excellent point-to-point repeatability and sample to sample reproducibility, and may be used for real-life quantitative analysis, as demonstrated by the rapid diagnosis of dual analytes of rhodamine 6G and crystal violet.