Aggregated-fluorescent detection of PFAS with a simple chip

In this study, aggregation-induced emission luminogens (AIEgen) are used for the detection of per- and poly-fluoroalkyl substances (PFAS) including perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and 1H,1H,2H,2H-perfluorooctanesulfonic acid (6:2FTS). A solution of acetone–water (solvent) containing AIE-PFAS is first formulated. From this solution, one droplet (1–2 μL) is dropped and trapped into a hole in a chip made of glass slide. When the droplet is exposed to air, both water and acetone can vaporise, but acetone vaporises much more quickly than water does due to its higher vapour pressure. Consequently, with the solvent volume shrinking, the concentrations of AIE and PFAS increase in the shrinking droplet while the water percentage increases. At a certain stage of this process, the micelle of PFAS surfactant forms, accompanied by AIE aggregation. After completely vaporising and drying on the bottom of the chip-hole, the aggregated AIE features fluorescence, the density of which can be effectively linked to the concentration of PFAS surfactant. Thus, a simple sensor is developed for PFAS detection in the range of 0.1–100 μM (41 ppb to 41 ppm for PFOA) within around 1 min using a 1–2 μL PFAS sample.