Molecularly Imprinted Polyaniline-Functionalized Lateral-Flow Membrane for Highly Sensitive and Selective Per- and...

Per- and polyfluoroalkyl substances (PFAS) contamination in water demands broad, accurate trace detection, yet current quantification relies heavily on laboratory-based liquid chromatography-tandem mass spectrometry with complex sample preparation and data processing, limiting rapid compliance screening and event-scale surveillance. In this work, we develop a novel PFAS sensor using a lateral-flow membrane functionalized with a chemiresistive molecularly imprinted polyaniline film for rapid, selective, and highly sensitive PFAS detection in water. Using perfluorooctanoic acid (PFOA) as the template, molecular imprinting endowed the polyaniline film with PFOA-specific adsorption. As capillary-driven transport carries the sample through the functionalized zone, PFOA is selectively adsorbed within molecularly imprinted cavities, and its carboxylic acid functionality then induces local protonic doping of polyaniline, thereby converting binding events into a large change in conductance. This sensing platform delivered a limit of detection of 3.1 pM (1.3 ng L^-1) and reliable readout within 15 min. The developed functionalized film exhibits remarkable selectivity toward structurally related PFAS compounds and shows robust resistance to interference from both other PFAS compounds and common environmental ions. Validation in drinking water, lake water, and river water samples confirmed high matrix spike recovery (95.0-107.1%) and minimal matrix effects, highlighting the sensor's applicability for real-world environmental monitoring. This work demonstrates a simple, cost-effective, and portable strategy for on-site ultratrace PFAS detection in diverse water matrices, supporting rapid environmental monitoring and compliance screening.