Colorimetric detection of perfluorooctanoic acid in water samples using fluorine-functionalized platinum...

Perfluorinated and polyfluoroalkyl substances (PFASs) are a class of artificially synthesized persistent organic pollutants, and their environmental exposure poses a huge threat to ecosystems and various organisms. The development of rapid and accurate PFAS content detection methods is of great significance for safeguarding human health and environmental protection. In this work, we developed a novel colorimetric sensor for high-selectivity detection of perfluorooctanoic acid (PFOA) based on fluorine-functionalized platinum nanoparticles (F-Pt NPs) with oxidase-like activity. The F-Pt NPs were synthesized through postmodification of the platinum nanoparticles with 1H,1H,2H,2H-perfluorodecylthiol (PFDT) and showed good oxidase-like activity using 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate. The fluorine groups on the surface of F-Pt NPs can effectively bind with PFOA through fluorine-fluorine (F⋯F) interaction, blocking some active sites of F-Pt NP nanozymes, leading to visible color changes. Under optimal experimental conditions, the absorption intensity of the F-Pt NPs/TMB system at 652 nm showed a good linear relationship with the target concentration, with a detection limit of 1 µg mL^-1. This method can meet the requirements for rapid screening of PFAS samples with conventional concentration, but the sensitivity still needs further improvement for detecting scenarios with ultra-low limits specified in national standards. In addition, the colorimetric sensor has good reproducibility, with a spiked recovery rate of 101.4% to 104.8% for PFOA in actual samples. This work introduces a novel colorimetric sensor for on-site detection of PFOA, which has good potential for application in environmental samples.