Ascorbic acid (AA) is a significant small biomolecule and plays a key role in many biochemical processes. In this work, a rapid turn-on fluorescent probe was developed for sensitive and selective sensing of AA based on carbon dots–MnO₂ nanocomposites. The nanocomposites were constructed by in situ synthesis of MnO₂ nanosheets in carbon dot (C-dot) solution, and the fluorescence of C-dots was quenched with the formation of the nanocomposites due to the fluorescence resonance energy transfer (FRET) from C-dots to the generated MnO₂ nanosheets. Once AA was introduced into the system, MnO₂ nanosheets were reduced to Mn²⁺ and the fluorescence of C-dots would be recovered. Under the optimized conditions, this method shows rapid and sensitive response toward AA, the assay time is 2 min and the limit of detection is 68 nM. Moreover, the carbon dots–MnO₂ nanocomposite based fluorescence sensing system was successfully employed to determine AA in commercial tablets with satisfactory results. Taking full advantage of C-dots and MnO₂ nanosheets, this probe shows remarkable properties including easy operation, low cost and good biocompatibility, and has great potential to be used in biological and clinical diagnostic applications.

中文翻译：

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基于碳点-MnO ₂纳米复合材料的快速灵敏的抗坏血酸检测荧光探针

抗坏血酸（AA）是一种重要的小生物分子，在许多生化过程中起着关键作用。在这项工作中，基于碳点-MnO ₂纳米复合材料，开发了一种快速开启的荧光探针，用于AA的灵敏和选择性传感。通过在碳点（C-dot）溶液中原位合成MnO ₂纳米片来构建纳米复合材料，由于C-的荧光共振能量转移（FRET），通过形成纳米复合材料，淬灭了C-点的荧光。点到生成的MnO ₂纳米片。将AA引入系统后，MnO ₂纳米片被还原为Mn ²⁺C点的荧光将被恢复。在优化的条件下，该方法显示出对AA的快速灵敏响应，测定时间为2分钟，检出限为68 nM。此外，基于碳点-MnO ₂纳米复合材料的荧光传感系统已成功用于测定商用片剂中的氨基酸，结果令人满意。该探针充分利用C点和MnO ₂纳米片的优势，具有易于操作，低成本和良好的生物相容性等优异性能，在生物学和临床诊断应用中具有巨大的潜力。