Typical fluorescent biosensors use fluorescently labeled ssDNA for target recognition and nanomaterials for signal transduction. Herein, we propose a reverse sensing strategy that MoN nanosheets are used for target recognition while fluorescein (FAM)-labeled ssDNA only serves for signal generation. We discover that MoN nanosheets show high fluorescence quenching ability (>95%) and selective recognition for sodium hexametaphosphate (SHMP). After FAM-labeled ssDNA is adsorbed on MoN nanosheets, the fluorescence is quenched due to the photoinduced electron transfer (PET) effect between FAM and MoN nanosheets. SHMP can specifically displace the adsorbed FAM-labeled ssDNA from MoN nanosheets, resulting in more than 80% fluorescence recovery on addition of 5 μmol L SHMP. This biosensor can sensitively detect SHMP down to 150 nmol L and selectively recognize SHMP over glucose, lactose, common amino acids, Zn, Mg, Ca and other phosphates (such as NaHPO, sodium pyrophosphate, sodium tripolyphosphate). This biosensor also shows great potential for the detection of SHMP in bacon sample. This work not only provides a facile sensitive and selective biosensor for SHMP but also exploits the application of transition metal nitrides in the field of sensing and biosensing.

中文翻译：

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用于荧光猝灭和目标识别的 Mo5N6 纳米片：高选择性传感六偏磷酸钠

典型的荧光生物传感器使用荧光标记的单链DNA进行目标识别，并使用纳米材料进行信号转导。在此，我们提出了一种反向传感策略，MoN 纳米片用于目标识别，而荧光素（FAM）标记的 ssDNA 仅用于信号生成。我们发现 MoN 纳米片表现出高荧光猝灭能力 (>95%) 和对六偏磷酸钠 (SHMP) 的选择性识别。 FAM 标记的 ssDNA 吸附在 MoN 纳米片上后，由于 FAM 和 MoN 纳米片之间的光致电子转移 (PET) 效应，荧光被猝灭。 SHMP 可以特异性地置换 MoN 纳米片上吸附的 FAM 标记的 ssDNA，添加 5 μmol·L SHMP 后荧光恢复率超过 80%。该生物传感器可以灵敏地检测低至150 nmol L的SHMP，并选择性地识别SHMP，而不是葡萄糖、乳糖、常见氨基酸、锌、镁、钙和其他磷酸盐（如Na2HPO、焦磷酸钠、三聚磷酸钠）。该生物传感器在检测培根样品中的 SHMP 方面也显示出巨大的潜力。这项工作不仅为SHMP提供了一种简便、灵敏、选择性的生物传感器，而且开拓了过渡金属氮化物在传感和生物传感领域的应用。