Tracking PFAS Using Nanomaterial-Based Sensors: Limitations, Advances, and Challenges

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are emerging contaminants of global concern, requiring sensitive and highly selective detection methods. Stringent demands imposed by the Environmental Protection Agency, with maximum contaminant levels set at 4.0 parts per trillion for PFAS individually in drinking water, are the primary driving force behind the development of novel sensors for PFAS. Pushing towards these ultra-low concentrations, however, reaches the limit of what can be reliably detected by field sensors, with PFAS optical and electrochemical inactivity, making it nearly impossible. Molecularly imprinted polymers and immunoassays offer the best chance of developing such sensors as they interact specifically with the active site, changing the optical or electrochemical response (fluorescence, impedance, voltage). Nanoparticulate metal oxides, carbon materials, including carbon dots, polymer coating, and MXenes have been put forward; however, several of these approaches have failed to achieve either the desired limit of detection, sensitivity, or selectivity. Here, we provide an overview of recent progress in nanomaterial-based PFAS sensors, with particular emphasis on strategies to enhance sensitivity, selectivity, and reliability in complex matrices. Finally, we outline key challenges and future perspectives toward robust, field-deployable PFAS sensing technologies.