A perfluoro-functionalised fluorescent maleimide probe for imaging of per- and polyfluoroalkyl substances

The persistence of per- and polyfluoroalkyl substances in the environment is becoming a major health concern, yet studying their fate and behaviour in complex media is limited due to the lack of suitable analytical methods. Here we proposed that a fluorescent polyfluoroalkyl probe could enable rapid tracing and negate drawbacks associated with current techniques. We synthesised a fluorescent probe containing a maleimide motif grafted to perfluorooctanoic acid. Using a conductivity assay, the critical micelle concentration was determined, and cryogenic transmission electron microscopy was further utilised to verify the presence of multilamellar vesicles. Titration of the fluorescent probe with a base enabled the determination of the acid dissociation constant, an important property of perfluorooctanoic acid. Results show that this fluorescent probe exhibits similar properties to perfluorooctanoic acid, and thus could reasonably act as an environmental proxy, with the benefit of strong, concentration-dependent and environmentally responsive fluorescence. This fluorescence offers a facile entry point for real-time tracing in various media. Further exploration of this tracer through plant, concrete, or soil studies could enable a better understanding of per- and polyfluoroalkyl substance behaviour in range of natural and artificial media.