Metal-Organic Framework Modified Microelectrodes for Electrochemical PFAS Monitoring in River Waters

Per-and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative environmental contaminants that pose significant risks to human health and water quality. Among them, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are highly regulated due to their toxicity and widespread occurrence at trace levels in drinking water. The need for rapid, sensitive, and field-deployable detection technologies has motivated the development of alternative sensing strategies beyond conventional laboratory-based methods. A porous metalorganic framework (MOF) incorporating gold nanoparticles is integrated onto microfabricated electrodes, enabling dual-mode detection via electrochemical impedance spectroscopy and voltammetry. It offers high surface area, tunable pore structures, and chemically adaptable metal nodes, enabling selective interactions with PFOA through electrostatic and hydrophobic mechanisms. Structural and electrochemical characterization confirmed the integrity and uniformity of the Au-Cr-MIL-101 nanocomposite and elucidated its molecular interaction with per-and polyfluoroalkyl substances (PFAS). The modified electrodes exhibit strong affinity toward long-chain PFAS, producing concentration-dependent changes in charge-transfer resistance and current response. Validation in river water samples confirms robust performance in complex matrices. This work highlights the potential of MOF-based electrochemical sensors as portable tools for rapid PFAS screening and real-time water quality monitoring.