Development of monolayer AuNPs decorated on an optical fiber facet for SERS analysis

In this paper, we present a novel strategy for fabricating surface-enhanced Raman scattering (SERS) optical probe modified monolayer gold nanoparticles (AuNPs) by a seed-mediated growth method. The morphology and optical properties of the samples were characterized by transmission electron microscopy, scanning electron microscopy, and UV-visible absorption spectroscopy. The results show that the resulting probes exhibit high sensitivity with a detection limit down to 10^-9mol/L for Methylene Blue solution and 10^-8mol/L for both Crystal Violet and Rhodamine 6G solutions. Furthermore, the probes show an excellent reproducibility (relative standard deviation of 9.2% at 1621cm^-1) and good stability, and the SERS spectra can be reproduced after storing the probes for one month in air. Finally, by finite-element simulations, we investigate the electromagnetic field distribution of the fiber facet modified with AuNPs. This work provides a promising potential of prepared SERS fiber probes and has broad application prospects in food safety, pesticide residue analysis, and environmental surveillance.