Per- and polyfluoroalkyl substances (PFAS) have raised significant concerns; however, their accurate detection in aqueous environments remains a major challenge. In this study, a host-guest molecularly imprinted polymer-based electrochemical sensor with enhanced antifouling properties were developed using β-cyclodextrin embedded with methylene blue (βCD-MB MIP). This sensor demonstrated sensitive and selective quantification of perfluorooctanoic acid (PFOA) in real water samples. The βCD-MB MIP was fabricated by electro-polymerizing βCD and MB in the presence of the target molecule, PFOA, where βCD served as the functional monomer and MB as the signaling probe. The incorporation of βCD endowed the MIP with a stable hydration layer, promoting hydrophilicity and inhibiting fouling, while ensuring effective electron transfer from MB, resulting in significant current responses and outstanding antifouling performance. This sensor exhibits excellent sensing capabilities towards PFOA with a detection limit of 1.57 pg mL −1 , covering a wide concentration range from 4.14 ng mL −1 to 41.4 mg mL −1 . It also displayed high selectivity for PFOA with an imprint factor of 6.5, which is five to seven times higher than that of other perfluorinated analogs. This study introduces an innovative platform for the rapid quantification of PFAS using redox-active MIPs and sets the groundwork for developing integrated sensors for continuous PFAS monitoring in water.
Perfluoro- and polyfluoroalkyl substances (PFAS) are widely used throughout the world and are extensively found in the environment. The detection of PFAS has become essential to ensuring environmental sustainability and human health. Herein, AuNRs were synthesized by the seed growth method and then the samples were coated with silver shells to form Au@Ag core–shell nanorods (Au@AgNRs). Au@AgNRs monolayer was prepared by oil–water self-assembly on a silicon wafer and then was constructed as a plasmonic AgNPs/Au@AgNRs sandwich structure for surface-enhanced Raman scattering (SERS) detection of PFAS. The shell thickness of Au@AgNRs was optimized and displayed a 11.9-fold SERS intensity higher than the pristine AuNRs. Moreover, the hotspots generated by the electromagnetic field coupling between the interlayer gap achieved 3.6-fold SERS signal enhancement compared to that of the Au@AgNRs monolayer. Besides, the excellent structural uniformity (RSD ∼ 8.0%) makes it ideal for quantitative SERS detection applications. More importantly, the use of the AgNPs/Au@AgNRs sandwich structure sensor enables the highly sensitive detection of model molecules (10–11 M) and quantitative detection of a wide range of fluorinated alkyl substances of perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA), and potassium perfluorobutanesulfonate (PPFBS), even with a portable Raman device. And the detection concentration can be down to 0.1 ppm for PFAS. This sensitive and quantitative SERS technique has promising prospects in the monitoring of fluorinated alkyl substance contaminations.
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