Bimetallic Fe3Cu-MOFs as Mimetic Enzyme and Fluorescent Probes for the Dual-Mode Detection of Uric Acid

In recent years, the global burden of gout has been increasing, and an excessively high level of blood uric acid is an important cause of gout attacks. The rapid detection of uric acid (UA) is of great significance for the auxiliary diagnosis of disease. We synthesized bifunctional Fe3Cu-MOFs that combined excellent peroxidase activity and fluorescence probe. UA reacts with uricase to generate H2O2, which could be catalyzed by the Fe3Cu-MOF to involve hydroxyl radicals (•OH) and singlet oxygen (1O2). And these free radicals can oxidize o-phenylenediamine (OPD) to 2,3-diaminophenazine (DAP) and the solution changes from colorless to yellow. Meanwhile, there is fluorescence resonance energy transfer (FRET) between DAP and Fe3Cu-MOF, resulting in the weakening of the blue fluorescence of Fe3Cu-MOF. Based on these mechanisms, we constructed a dual-mode sensor for UA detection. The detection ranges of the colorimetric method and the ratiometric fluorescence method of this sensor are 1–250 and 0.5–250 μM, respectively, and the limits of detection are 0.43 and 0.30 μM, respectively. These results indicate that the sensor has excellent sensitivity for UA detection. In addition, we have also successfully applied this sensor to the detection of UA content in human serum samples and urine samples.