Dual-modal detection of perfluorooctanoic acid (PFOA) using a single polymer platform: ACQ and IDA approaches†

Perfluorooctanoic acid (PFOA), a prominent member of per- and polyfluoroalkyl substances (PFAS), poses significant environmental and health risks due to its persistence and toxicity. We report a dual-modal sensing strategy employing the water-soluble conjugated polyelectrolyte, poly(3,3′-((1,4-phenylenebis(oxy))bis(propane-3,1-diyl))bis(1-methyl-1H-imidazol-3-ium) bromide) (PPMI), for instant detection of PFOA. PPMI exhibits aggregation-caused quenching (ACQ) and indicator displacement assay (IDA) “turn-on” responses towards PFOA in aqueous media. The ACQ mechanism yields a limit of detection (LOD) of 0.21 μM. In contrast, the IDA approach achieves a remarkably lower LOD of 16.1 nM. Notably, PPMI detects PFOA in the presence of potentially interfering ions and distinguishes it from structurally similar PFOA analogues. This dual-modal approach offers a reliable method for PFOA monitoring in environmental water samples.