A sensitive fluorescence detection strategy for H2O2 and glucose by using aminated Fe–Ni bimetallic MOF as fluorescent nanozyme

An aminated Fe-Ni bimetallic metal-organic framework (Fe3Ni-MOF-NH2) with both peroxidase-like activity and fluorescence properties was developed. Fe3Ni-MOF-NH2 possessed the enhanced peroxidase-like activity through the enhanced electron transfer process and hydroxyl radical (·OH) generation. It was found that the amino group endowed the material with fluorescent property and the metal site Ni in Fe3Ni-MOF-NH2 could also enhance the fluorescence emission intensity (Ex = 345 nm, Em = 452 nm). Based on the dual excellent performance of Fe3Ni-MOF-NH2, a novel sensitive fluorescence detection strategy for H2O2 and glucose was designed and achieved. First, Fe3Ni-MOF-NH2 converted H2O2 to ·OH by exerting peroxidase-like activity, and ·OH converts catechol to o-benzoquinone. Then, the amino group in Fe3Ni-MOF-NH2 connected to o-benzoquinone, which resulted in its fluorescence quenching. The detection limit of H2O2 was as low as 5 nM. Combined with glucose oxidase which can oxidize glucose and produce H2O2 the glucose could be indirectly determined with a detection limit of 40 nM. The method was applied to the detection of low-level glucose in human urine samples with good recoveries and reproducibilities.