A Colorimetric Sensor Based on Cationic F-MOF/Hemin-Graphene Peroxidase Nanozymes for the Detection of Perfluorinated Compounds

Perfluorinated compounds (PFCs), as persistent and highly toxic emerging pollutants, require effective analytical methods for accurate environmental monitoring. While current research predominantly focuses on individual PFCs, real environmental matrices typically contain multiple coexisting PFCs, making single-analyte detection approaches insufficient for comprehensive risk assessment. In this work, a nanozyme colorimetric sensor is developed for the detection of both individual and mixed PFCs. Specifically, a cationic fluorinated metal-organic framework (F-MOF) is intercalated and anchored onto the interlayers and surface of hemin-functionalized graphene (H-Gr), forming a composite (F-MOF/H-Gr) with peroxidase-like catalytic activity. The F-MOF/H-Gr selectively recognizes and enriches PFCs through electrostatic attraction, coordination, and fluorine-fluorine affinity. The adsorbed PFCs introduce steric hindrance on the material surface, inhibiting its catalytic activity. This inhibition establishes a correlation between catalytic performance and PFC concentration. By integrating a TMB-based colorimetric reaction with UV-vis spectrophotometry, the system achieves efficient PFC detection. The sensor exhibits excellent linear responses across two concentration ranges (0.001-0.1 and 0.1-300 μM) for PFCs, with a detection limit as low as 0.8 nM, demonstrating outstanding sensitivity and selectivity. This work proposes a rapid and generalizable colorimetric strategy for PFC detection, offering a promising approach for practical environmental monitoring.