Designing of fluorine-functionalized MIL-88B MOF for homogeneous electrochemical-colorimetric-smartphone tri-model sensing of perfluorooctane sulfonate

In the last few years, many interesting electrochemical methods have been developed for the quantitative detection of perfluorooctane sulfonate (PFOS, a “forever chemical”), whereas they generally require complex electrode modifications coupled with just a single signal. For effectively improving the detection efficiency and reliability, herein we firstly designed and prepared an iron-based MOF (MIL-88B) functionalized with fluorine (F) nanozyme (F-FeMOF) which can offer prominent peroxide-like activity and selectively recognize the PFOS target. Meanwhile, the nanozyme activity of F-FeMOF would be inhibited in the presence of PFOS. By using o -phenylenediamine as the catalytical substrate and its product 2,3-diaminophenazinc in homogeneous solution as the signal source which can make the color of sensing system change and offer reduction current, a homogeneous electrochemical, colorimetric and smartphone tri-model sensing strategy was then proposed to detect PFOS upon integrating with Image J software. Under the optimized detection conditions, the as-proposed sensing platform could offer prominent analytical performances (10–1000 nM for the linearity and 0.004 nM for the detection limit). In addition, the related sensing and catalytical mechanisms were investigated in detail, and the application in real water samples were confirmed. We expected this tri-mode sensing platform based on F-FeMOF nanozyme could open up a new avenue for the PFOS analysis.