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<p>A dual-metal metal–organic framework (MOF)-based nanozyme, Fe/Mn-MOF/CeO<sub>2</sub>, with high peroxidase-like activity was successfully synthesized via a stepwise solvothermal-hydrothermal combined liquid-phase composite strategy. A colorimetric/fluorescence dual-mode sensing platform was fabricated for the detection of norfloxacin (NOR) in milk and honey. The material takes advantage of the synergistic electronic effect of Fe/Mn bimetallic active sites and the reversible Ce<sup>4+</sup>/Ce<sup>3+</sup> valence cycle to remarkably enhance its peroxidase-like activity. The nanozyme can trigger the decomposition of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) to generate reactive oxygen species (ROS), which oxidizes colorless 3,3’,5,5’-tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB). In the established sensing system, NOR can elevate the absorbance signal at 652&#xa0;nm and quench the fluorescence emission at 435&#xa0;nm (λ<sub>ex</sub> = 360&#xa0;nm), thereby enabling dual-signal quantitative detection of NOR. Under optimized experimental conditions, the colorimetric mode afforded a linear detection range of 0.100–225 µM and a limit of detection (LOD) of 78.0 nM, while the fluorescence mode delivered a linear range of 0.100–225 µM and an LOD of 46.0 nM. The freshly prepared nanozyme exhibits selectivity against both structural analogs and non-specific interferents, as well as outstanding long-term stability for up to 90 days. In spike-and-recovery experiments with real milk and honey samples, the established sensor presented satisfactory recoveries of 98.6%–103% and relative standard deviation (RSD) values less than 5.00%. This work proposes an innovative sensing strategy for the quantitative determination of antibiotic residues in milk, honey, and other dairy products, which holds great potential for improving the on-site monitoring capability of food safety.</p> Graphical Abstract <p></p>

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Colorimetric/fluorescent dual-mode detection of norfloxacin in food samples using Fe/Mn-MOF/CeO2 nanozyme with high peroxidase-like activity

  • 期刊论文

  • 发表日期：

    2026年8月5日

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  • Jiaqi Zhang,
  • Shijie Chen,
  • Xiang Li,
  • Ning Liu,
  • Dongxuan Guo,
  • Xinjia Zhang,
  • Jianhua Zheng,
  • Renjiang Lv,
  • Wencheng Gu

摘要

A dual-metal metal–organic framework (MOF)-based nanozyme, Fe/Mn-MOF/CeO2, with high peroxidase-like activity was successfully synthesized via a stepwise solvothermal-hydrothermal combined liquid-phase composite strategy. A colorimetric/fluorescence dual-mode sensing platform was fabricated for the detection of norfloxacin (NOR) in milk and honey. The material takes advantage of the synergistic electronic effect of Fe/Mn bimetallic active sites and the reversible Ce4+/Ce3+ valence cycle to remarkably enhance its peroxidase-like activity. The nanozyme can trigger the decomposition of hydrogen peroxide (H2O2) to generate reactive oxygen species (ROS), which oxidizes colorless 3,3’,5,5’-tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB). In the established sensing system, NOR can elevate the absorbance signal at 652 nm and quench the fluorescence emission at 435 nm (λex = 360 nm), thereby enabling dual-signal quantitative detection of NOR. Under optimized experimental conditions, the colorimetric mode afforded a linear detection range of 0.100–225 µM and a limit of detection (LOD) of 78.0 nM, while the fluorescence mode delivered a linear range of 0.100–225 µM and an LOD of 46.0 nM. The freshly prepared nanozyme exhibits selectivity against both structural analogs and non-specific interferents, as well as outstanding long-term stability for up to 90 days. In spike-and-recovery experiments with real milk and honey samples, the established sensor presented satisfactory recoveries of 98.6%–103% and relative standard deviation (RSD) values less than 5.00%. This work proposes an innovative sensing strategy for the quantitative determination of antibiotic residues in milk, honey, and other dairy products, which holds great potential for improving the on-site monitoring capability of food safety.

Graphical Abstract