mSiO2-CQDs-Au@Ag nanocomposites for sensitive SERS detection of amisulpride: performance and mechanistic insights

Rational design of a multifunctional mSiO 2 -CQDs-Au@Ag nanocomposite. • Au@Ag and CQDs synergistically strengthen the SERS response. • The substrate achieves an enhancement factor of 1.0 × 10 9 . • Amisulpride in seawater is detected at 6.1 × 10 −9 mol·L −1 . • Charge transfer assisted enhancement is revealed experimentally. Pharmaceutically active compounds (PhACs) are receiving increasing attention because of their widespread use and continuous release into aquatic environments. Among them, amisulpride (AMI), a widely prescribed antipsychotic drug, is a plausible aquatic contaminant due to its release through wastewater and incomplete metabolic removal. Herein, Au@Ag core–shell nanoparticles were prepared using β-cyclodextrin as both the reducing agent and stabilizer, and further assembled with carbon quantum dots (CQDs) and mesoporous silica (mSiO 2 ) to construct a composite Surface-enhanced Raman scattering (SERS) substrate, mSiO 2 -CQDs-Au@Ag, for sensitive AMI detection. The substrate exhibited strong enhancement capability, with an enhancement factor (EF) as high as 1.0 × 10 9 . When applied to the detection of AMI in seawater, the proposed platform achieves a low limit of detection (LOD) of 6.1 × 10 −9 mol·L −1 , together with a good linearity (R 2  = 0.993). Combined theoretical and experimental analyses indicated that CQDs not only participate in interfacial charge transfer, but also contribute to analyte adsorption. This work offers a rational strategy for constructing semiconductor-integrated SERS platforms for sensitive detection and demonstrates its promising potential for environmental monitoring of emerging organic pollutants. Download: Download high-res image (91KB) Download: Download full-size image