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<p>Manganese dioxide (MnO<sub>2</sub>)-based heterogeneous catalysts have gained significant attention in nanozyme research due to their exceptional oxidase-mimicking capabilities. This work reports the rational design of MnO<sub>2</sub> functionalized magnetic carbon nanotubes (Fe<sub>3</sub>O<sub>4</sub>@C@MnO<sub>2</sub>) through a multistep synthesis strategy. The magnetic N-doped hollow carbon substrate (Fe<sub>3</sub>O<sub>4</sub>@C) was first synthesized via controlled pyrolysis of FeOOH-coated polydopamine precursors. Subsequent interfacial redox reaction with KMnO<sub>4</sub> enabled the in situ deposition of ultrathin MnO<sub>2</sub> nanosheets on the nanotube substrate, forming a triple-component coaxial architecture. This hollow structure not only facilitates dense MnO<sub>2</sub> deposition but also maintains robust magnetic responsiveness. The obtained Fe<sub>3</sub>O<sub>4</sub>@C@MnO<sub>2</sub> exhibits remarkable enzyme-mimetic capability, catalyzing TMB chromogenic conversion with 0.92-fold enhanced catalytic performance relative to pristine MnO<sub>2</sub>. Systematic mechanistic studies reveal that tannic acid (TA) competitively inhibits ·OH radical generation via MnO<sub>2</sub>-TA complexation, while the carbon interlayer enhances electron transfer efficiency. Owing to the superior enzyme-mimetic performance of Fe<sub>3</sub>O<sub>4</sub>@C@MnO<sub>2</sub> and their inhibition effect by TA, a sensitive colorimetric biosensing assay was fabricated, achieving a&#xa0;TA detection limit of 0.029&#xa0;μM with&#xa0;a 0.096–4.82&#xa0;μM linear concentration&#xa0;range. This work exemplifies the synergy of structural engineering and component optimization in designing multifunctional nanozymes, showing potential applications in food quality monitoring, environmental analysis, and point-of-care diagnostics.</p> Graphical Abstract <p></p>

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Hierarchical Fe3O4@C@MnO2 nanozymes: bridging structural engineering to on-site biosensing of tannic acid

  • 期刊论文

  • 发表日期：

    2025年8月16日

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  • Jingjing Meng,
  • Lu Han,
  • Lu Li,
  • Xue-bo Yin,
  • Jing Zheng

摘要

Manganese dioxide (MnO2)-based heterogeneous catalysts have gained significant attention in nanozyme research due to their exceptional oxidase-mimicking capabilities. This work reports the rational design of MnO2 functionalized magnetic carbon nanotubes (Fe3O4@C@MnO2) through a multistep synthesis strategy. The magnetic N-doped hollow carbon substrate (Fe3O4@C) was first synthesized via controlled pyrolysis of FeOOH-coated polydopamine precursors. Subsequent interfacial redox reaction with KMnO4 enabled the in situ deposition of ultrathin MnO2 nanosheets on the nanotube substrate, forming a triple-component coaxial architecture. This hollow structure not only facilitates dense MnO2 deposition but also maintains robust magnetic responsiveness. The obtained Fe3O4@C@MnO2 exhibits remarkable enzyme-mimetic capability, catalyzing TMB chromogenic conversion with 0.92-fold enhanced catalytic performance relative to pristine MnO2. Systematic mechanistic studies reveal that tannic acid (TA) competitively inhibits ·OH radical generation via MnO2-TA complexation, while the carbon interlayer enhances electron transfer efficiency. Owing to the superior enzyme-mimetic performance of Fe3O4@C@MnO2 and their inhibition effect by TA, a sensitive colorimetric biosensing assay was fabricated, achieving a TA detection limit of 0.029 μM with a 0.096–4.82 μM linear concentration range. This work exemplifies the synergy of structural engineering and component optimization in designing multifunctional nanozymes, showing potential applications in food quality monitoring, environmental analysis, and point-of-care diagnostics.

Graphical Abstract