Bottom-up assembly of Au@Ag plasmonic nanocrystals: Issues to be addressed to achieve a good SERS substrate

Abstract Plasmonic substrate is a key component in surface-enhanced Raman scattering (SERS) spectroscopy to boost the Raman signal of analytes. The quality of SERS substrate is assessed primarily on the basis of its sensitivity, reproducibility and robustness. Despite major achievements in the field over the last decade, reliable SERS substrates fabricated by the bottom-up assembly of colloids are still rare on the market not to say absent in routine analytics. In this work, we investigated several important aspects from the optimization of colloids organization on solid support to the SERS analytical performance (sensitivity, stability and reproducibility) for detecting pesticides such as thiram. We show that the surfactant surrounding colloids usually considered as a limitation for the detection of macromolecules, proved to be a major advantage to induce assembly of nanoparticles on solid support and to improve the affinity of hydrophobic analytes for metallic surface and for the long-term stability of the substrate.