A ratiometric fluorescence sensor based on Eu³⁺@tetrafluorosuccinic acid functionalized UiO-67: Enhancing the detection performance of ofloxacin through pre-concentration effect

The excessive use of ofloxacin (OFL) has led to its persistent residues in water sources and animal-derived foods, posing a threat to human health. Therefore, it is urgent to develop fluorescent sensing materials capable of detecting ofloxacin in water environments and food matrices. Herein, a novel Eu³⁺@tetrafluorosuccinic acid-functionalized ratiometric fluorescent material Eu³⁺@UiO-67-TFSA was prepared by a two-step post-synthetic modification of UiO-67. In the concentration range of 1-15 μM, the Eu³⁺@UiO-67-TFSA had a limit of detection (LOD) of 0.42 μM for OFL, which was approximately 3.90 times lower than that of the non-fluorinated Eu³⁺@UiO-67-SA (LOD = 1.64 μM). The improved sensing performance could be attributed to the pre-concentration effect provided by the Eu³⁺@UiO-67-TFSA. The possible detection mechanism was systematically elucidated through relevant experiments and density functional theory (DFT) calculation. Moreover, the constructed smartphone-assisted visual sensing platform was successfully applied to detect OFL in actual food samples and real water environment samples.