Highly sensitive size-sieving detection of pharmaceutical and pesticide residues in water using ZIF-8-coated gold superparticles as SERS substrate

The accurate detection of trace pharmaceuticals and pesticides in aquatic environments remains a formidable analytical challenge, primarily due to ultralow contaminant concentrations, complex matrix interferences, and the structural similarity among many target analytes—factors that severely compromise selectivity and reliability in conventional sensing approaches. Surface-enhanced Raman scattering (SERS) offers a powerful alternative owing to its exceptional sensitivity and molecular fingerprinting capability. However, its practical deployment in real-world water samples has been impeded by insufficient selectivity and inadequate signal discrimination for structurally analogous compounds. To overcome these limitations, we present an innovative core-shell SERS substrate—gold superparticles encapsulated within a zeolitic imidazolate framework-8 (denoted GSPs@ZIF-8)—engineered to synergistically combine molecular preconcentration, matrix exclusion, and electromagnetic field enhancement. The porous ZIF-8 shell selectively enriches trace thiazole/imidazole-type analytes while excluding interfering species, thereby addressing the dual challenges of low abundance and matrix complexity. Meanwhile, the precisely controlled nanogaps between GSPs generate intense and uniform “hot spots”, delivering an enhancement factor of up to 3.01 × 10 8 and enabling a detection limit as low as 0.1 nM for 2-mercaptobenzothiazole (MBT). Critically, the GSPs@ZIF-8 platform achieves discrimination and simultaneous quantification of three highly similar compounds—MBT, 5-amino-2-mercaptobenzothiazole (AMT), and 2-mercaptobenzimidazole (MBI)—in mixed aqueous solutions. This work establishes a robust, selective, and ultrasensitive SERS strategy for monitoring structurally homologous contaminants in complex environmental matrices, paving the way toward practical on-site water quality assessment.