Conventional fluorescent probes are either easily photobleached or non-biodegradable, which often leads to the unstable fluorescence signal output and long-term biological toxicity. Therefore, the development of novel fluorescent materials with both excellent photostability and biodegradability is of great significance for further broadening their application in numerous research fields. In this work, Nb₂C quantum dots (Nb₂C QDs) with pristine crystallographic structures of Nb₂C MXene phases and surface oxygen-containing species are synthesized by an ultrasound assisted physicochemical exfoliation in tetrapropylammonium hydroxide. Detailed analyses indicate that the Nb₂C QDs not only possess excellent chemical- and photo-stable fluorescence emission but also achieve successful application in fluorescence sensing of heavy metal ions and fluorescence imaging. More importantly, it is confirmed that the Nb₂C QDs present high biocompatibility and unique biodegradation property responsive to human myeloperoxidase, implying the application safety of Nb₂C QDs in vivo. Under the background of ever-growing and stringent requirements for biosafety and technical stability, the chemical- and photo-stability, biocompatibility, biodegradability, and most importantly the promising fluorescence sensing/imaging characteristic of the obtained Nb₂C QDs may argue well for their future applications in environmental monitoring, biomedical diagnosis, visual display, and anti-counterfeiting.

常规的荧光探针很容易被光漂白或不可生物降解，这常常导致不稳定的荧光信号输出和长期的生物毒性。因此，开发具有优异的光稳定性和生物降解性的新型荧光材料对于进一步扩大其在众多研究领域中的应用具有重要意义。在这项工作中，NB ₂ Ç量子点（NB ₂ ç量子点）有Nb的原始晶体结构₂ çMXene相和表面含氧物质是由辅助物理化学剥离在氢氧化四丙铵的超声合成。详细分析表明，Nb ₂C QD不仅具有出色的化学和光稳定性荧光发射，而且在重金属离子的荧光传感和荧光成像中也取得了成功的应用。更重要的是，已证实Nb ₂ C QDs具有高的生物相容性和对人髓过氧化物酶的响应，具有独特的生物降解特性，这意味着Nb ₂ C QDs在体内的应用安全性。在对生物安全性和技术稳定性的要求日益严格的背景下，所得Nb ₂的化学和光稳定性，生物相容性，生物降解性以及最重要的有希望的荧光传感/成像特性C QD可能会很好地证明其在环境监测，生物医学诊断，视觉显示和防伪方面的未来应用。