Single-Atom Catalyst-Based Fluorescence Sensor Array for the Detection of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFASs), as a class of persistent organic pollutants, pose a great risk to the ecological environment and human health. The development of rapid and accurate assays for PFASs detection is therefore critically important, yet remains challenging. In this work, we designed a fluorescence sensor system based on single-atom catalysts (SACs) for the detection of PFASs. PFASs could block the atom-specific catalytic sites through hydrophobic-hydrophobic interaction and electrostatic interaction, attenuating the catalytic activity, which leads to the weakening of the colorimetric reaction of 3,3',5,5'-tetramethylbenzidine (TMB). The resultant colored product (TMBOX) exhibits a substantially reduced fluorescence quenching effect on subsequently added fluorescent carbon dots (CDs). In other words, the bright fluorescence of CDs was well maintained in the presence of a trace amount of PFASs; otherwise, it was significantly quenched in the absence of PFASs. The sensor for PFOA was proposed based on Fe SACs with a detection limit of 1.8 ppb (4.4 nM). Furthermore, when various PFASs interact with a series of SACs, different fluorescence intensity changes could be observed due to the different affinities. Thus, three SACs (Fe, Co, and Cu SACs) were used as the sensing units to construct a fluorescence sensor array. When combined with linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA), qualitative and quantitative detection of six structural PFASs was achieved. This study provides a novel strategy for rapid screening and multidimensional sensing analysis of organic pollutants in real environmental water samples.