Benefiting from the special structure feature, zeolitic imidazolate frameworks (ZIFs) have emerged as a carrier for enzyme immobilization. However, the sensitivity of the immunosensor with ZIFs needs further enhancement. Herein, a “three-in-one” label mediated by tannic acid (TA) was designed, demonstrating high enzyme activity, cascade signal amplification capability, and high coupling effectivity with antibodies. The acid property of TA was used as an etchant to etch ZIFs in situ for the generation of hollow ZIFs, which retained the conformational freedom of glucose oxidase for preserving their excellent catalytic activity. The TA on the surface of ZIFs coordinated Fe ions through its phenol groups, forming metal polyphenol network films, which possessed peroxidase-like activity for cascade signal amplification. Meanwhile, the large amount of catechol groups of TA improved the coupling efficiency of antibodies. Based on the proposed “three-in-one” label, a novel fluorescence immunosensor was developed for the sensitive detection of O157:H7. The limit of detection of the fluorescence immunosensor was 1.35 × 10 CFU mL and 12.51-fold lower than that of traditional immunoassay. This proposed strategy provides a convenient method for preparing hollow ZIFs, facilitating the applications of ZIFs in the fields of biosensors.

中文翻译：

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单宁酸介导的中空生物催化沸石咪唑酯框架作为增强荧光免疫传感器灵敏度的“三合一”标签

受益于特殊的结构特征，沸石咪唑酯骨架（ZIF）已成为酶固定化的载体。然而，ZIF 免疫传感器的灵敏度需要进一步提高。本文设计了一种由单宁酸（TA）介导的“三合一”标签，具有高酶活性、级联信号放大能力以及与抗体的高偶联效率。利用TA的酸性作为蚀刻剂原位蚀刻ZIF，生成中空ZIF，该中空ZIF保留了葡萄糖氧化酶的构象自由度，从而保持了其优异的催化活性。 ZIFs表面的TA通过其酚基团与Fe离子配位，形成金属多酚网络膜，该膜具有类似过氧化物酶的活性，可实现级联信号放大。同时，TA中大量的儿茶酚基团提高了抗体的偶联效率。基于所提出的“三合一”标签，开发了一种新型荧光免疫传感器，用于灵敏检测 O157:H7。荧光免疫传感器的检测限为1.35×10 CFU mL，比传统免疫分析低12.51倍。该策略为制备空心ZIF提供了一种便捷的方法，促进了ZIF在生物传感器领域的应用。