Ag Nanoparticles-Decorated 2D WSe2 as Highly Sensitive Surface-Enhanced Raman Spectroscopy Substrates for Nitrofurantoin Detection

Nitrofurantoin, a derivative of nitrofuran, has been banned due to its carcinogenic potential, necessitating sensitive detection methods to monitor its illegal use and facilitate the clinical diagnosis of associated conditions. In this study, a composite structure of silver nanoparticles (AgNPs) on tungsten diselenide (WSe₂) sheets was developed for the detection of nitrofurantoin using surface-enhanced Raman spectroscopy (SERS). AgNPs prepared via mechanical exfoliation were selectively distributed on the surface of two-dimensional (2D) transition-metal dichalcogenides, resulting in enhanced SERS performance for molecular detection. The AgNPs/WSe₂ substrate demonstrated a detection limit (LOD) for rhodamine 6G molecules as low as 10^–10 M, outperforming previously reported Au/WSe₂ composite structures. Notably, the AgNPs/WSe₂ substrate achieved an LOD of 10^–9 M for nitrofurantoin, surpassing other SERS detection methods reported to date. Furthermore, the substrate can quantitatively detect nitrofurantoin in milk solutions with an LOD of 10^–6 M, demonstrating its potential in practical application. Its remarkable Raman enhancement effect may come from the synergistic effect of electromagnetic mechanism enhancement of AgNPs and chemical mechanism enhancement of 2D WSe₂. The excellent uniformity and stability of the AgNPs/WSe₂ composite make it a promising candidate for sensitive and reproducible SERS-based molecular detection.