Sensitive Detection of Perfluoroalkyl Substances Using MXene–AgNP-Based Electrochemical Sensors

Abstract

Per-and polyfluoroalkyl substances (PFAS) pose a significant threat to the environment due to their persistence, ability to bioaccumulate, and harmful effects. Methods to quantify PFAS rapidly and effectively are essential to analyze and track contamination, but measuring PFAS down to the ultralow regulatory levels is extremely challenging. Here, we describe the development of a low-cost sensor that can measure a representative PFAS, perfluorooctanesulfonic acid (PFOS), at the parts per quadrillion (ppq) level within 5 min. The method combines the ability of PFOS to bind to silver nanoparticles (AgNPs) embedded within a fluorine-rich Ti 3 C 2 -based multilayered MXene, which provides a large surface area and accessible binding sites for direct impedimetric detection. Fundamentally, we show that MXene−AgNPs are capable of binding PFOS and other long-chain PFAS compounds, though the synergistic action of AgNPs and MXenes via electrostatic and F−F interactions. This binding induced concentration-dependent changes in the charge-transfer resistance, enabling rapid and direct quantification with extremely high sensitivity and no response to interferences. The sensor displayed a linear range from 50 ppq to 1.6 ppt (parts per trillion) with an impressively low limit of detection of 33 ppq and a limit of quantification of 99 ppq, making this sensor a promising candidate for low-cost screening of the PFAS content in water samples, using a simple and inexpensive procedure.

First Direct Gravimetric Detection of Perfluorooctane Sulfonic Acid (PFOS) Water Contaminants, Combination with Electrical Measurements on the Same Device—Proof of Concepts

“…In a just-published paper, silver nanoparticles embedded within a fluorine-rich Ti3C2-based multilayered MXene were binding several PFAS contaminants and showed specificity of the sensor for long-chain PFAS, and no interferences from structurally similar compounds lacking F, small molecules, organic matter, and ions. EIS was used, and a very low LOD of 33 ppq was achieved [64]. However, the measurements were performed in PBS buffer with Fe(CN)6 3−/4− redox probe, which questions constant water monitoring applications.…”