Recently, 2D niobium carbide MXene has drawn vast attention due to its merits of large surface area, good metallic conductivity, and tunable band gap, making it desirable for various applications. However, the usage of highly toxic fluoride‐containing etchant and quite long etching time in the conventional synthesis route has greatly hindered further exploration of MXene, especially restricting its biomedical application. Herein, novel fluoride‐free Nb₂CT_x nanosheets are prepared by a facile strategy of electrochemical etching (E‐etching) exfoliation. Taking advantage of rapid aluminum clearance, excellent chemical stability, and biocompatibility from the MXene by E‐etching, fluoride‐free Nb₂CT_x/acetylcholinesterase‐based biosensors are constructed for phosmet detection with the limit of detection down to 0.046 ng mL⁻¹. The fabricated Nb₂CT_x‐based biosensor is superior to the counterpart from hydrofluoric acid‐etched Nb₂CT_x, indicating that fluoride‐free MXene can enhance the enzyme activity and electron transfer in the biosensor. The results prove that the fluorine‐free MXene shows promise for developing biosensors with high performance of ultrahigh sensitivity and selectivity. It is highly expected that the fluoride‐free MXene as a stable and biocompatible nanoplatform has great potential to be expanded to many other biomedical fields.

中文翻译：

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无氟二维碳化铌MXenes是稳定且生物相容的纳米平台，用于超高灵敏度的电化学生物传感器

近来，二维碳化铌MXene由于具有大表面积，良好的金属导电性和可调节的带隙等优点而备受关注，使其成为各种应用的理想之选。但是，在常规合成路线中使用剧毒的含氟蚀刻剂和相当长的蚀刻时间极大地阻碍了MXene的进一步开发，特别是限制了其生物医学应用。在此，通过一种简便的电化学蚀刻（E蚀刻）剥离策略制备了新型的无氟Nb ₂ CT _x纳米片。通过快速蚀刻，无氟的Nb ₂ CT _x从MXene中获得铝的快速清除，出色的化学稳定性和生物相容性基于/乙酰胆碱酯酶的生物传感器可用于荧光检测，检测限低至0.046 ng mL ^-1。制成的基于Nb ₂ CT _x的生物传感器优于氢氟酸蚀刻的Nb ₂ CT _x，这表明不含氟的MXene可以增强生物传感器中的酶活性和电子转移。结果证明，无氟MXene具有开发具有超高灵敏度和选择性的高性能生物传感器的潜力。高度期望无氟MXene作为一种稳定且具有生物相容性的纳米平台具有巨大的潜力，可以扩展到许多其他生物医学领域。