In this work, an ascorbic acid (AA) sensing platform by employing MnO₂ nanosheets and gold nanocluster (AuNCs) as a ratiometric fluorescent probe has been reported. AuNCs serves as a fluorescence reporter and MnO₂ nanosheets play three roles, such as fluorescence quencher, AA recognition unit and artificial enzyme in this sensing system. The fluorescence of AuNCs could efficiently be quenched by MnO₂ nanosheets through fluorescence resonance energy transfer (FRET), and MnO₂ nanosheets would oxidize non-fluorescent thiamine (vitamin B1, VB₁) to blue fluorescent thiochrome (oxVB₁) at the same time. However, the introduction of AA could lead to the etching of MnO₂ nanosheets and the recovery of the fluorescence of AuNCs. Based on this phenomenon and the redox reaction between MnO₂ nanosheets and AA, we have developed a sensitive ratiometric fluorescent method for AA detection. The proposed ratiometric fluorescent probe exhibited a good linearity range of 1.5–100.0 μmol·L⁻¹ and a low limit of detection (LOD) of 0.45 μmol·L⁻¹.

在这项工作中，已经报道了通过使用MnO ₂纳米片和金纳米簇（AuNCs）作为比例荧光探针的抗坏血酸（AA）传感平台。AuNCs用作荧光报告分子，而MnO ₂纳米片在该传感系统中起着三个作用，例如荧光淬灭剂，AA识别单元和人工酶。MnO ₂纳米片可以通过荧光共振能量转移（FRET）有效地淬灭AuNCs的荧光，并且MnO ₂纳米片可以同时将非荧光硫胺素（维生素B1，VB ₁）氧化为蓝色荧光硫色素（oxVB ₁）。 。但是，AA的引入可能导致MnO ₂的腐蚀纳米片和AuNCs荧光的恢复。基于这种现象以及MnO ₂纳米片与AA之间的氧化还原反应，我们开发了一种灵敏的比例荧光法检测AA。所提出的比率荧光探针表现出1.5-100.0μmol·L的良好的线性范围^-1 0.45μmol·L的和检测（LOD）的下限^-1。