Surface-enhanced Raman scattering substrate based on cysteamine-modified gold nanoparticle aggregation for highly sensitive pentachlorophenol detection

A new surface-enhanced Raman scattering (SERS) substrate based on cysteamine-modified gold nanoparticles (AuNPs) was successfully immobilized onto a glass surface via the strong covalent interaction of the Au–S bond, and this substrate was used to monitor pentachlorophenol (PCP) in water samples. The cysteamine monolayer on AuNPs can effectively adsorb PCP onto the surface of the substrate through electrostatic interactions. The Raman bands of cysteamine can be used as an internal standard for quantitative analysis. Quantitative analysis can be performed in ultrapure water and tap water without involving any sample pretreatment, and the minimum detectable concentration is up to 1 nM (0.26 μg L−1), which is much lower than the maximum contaminant level (MCL, 1 μg L−1) prescribed by the U.S. Environmental Protection Agency (EPA). The proposed PCP sensor shows excellent long-term stability and good uniformity. Thus, the proposed SERS-based assay is a valuable tool demonstrating high potential for PCP monitoring in the environment.