Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, Brisbane, Queensland, 4072, Australia.
Nantong University, No. 9, Suyuan Road, Nantong, Jiangsu, 226019, China.
Talanta. 2024 Jan 1;266(Pt 2):125051. doi: 10.1016/j.talanta.2023.125051. Epub 2023 Aug 6.
Ascorbic acid (or widely known as vitamin C, VC) is an essential antioxidant and a free radical scavenger in human body. The appeal for reliable fluorescent nanosensors always promotes the development of VC probe. In this work, a pre-oxidized Eu-probe (denoted as Eu-NO) was synthesized. Without VC, Eu-NO was nearly non-emissive owing to the inefficient ligand energy transfer (ET) to Eu ion (caused by mismatched ligand level and long distance to Eu, as revealed by single crystal analysis and emissive parameters). By adding VC, the pre-oxidized ligand was deoxidized and its ET to Eu ion became efficient (confirmed by electrochemical analysis), with Eu(III) red emission intensity obviously increased. Then Eu-NO was doped into a porous host bio-MOF-1 for ascorbic acid detection (denoted as Eu-NO@MOF). The molecular sieving effect of bio-MOF-1 improved sensing selectivity, and bio-MOF-1 blue emission (421 nm) was applied as a reference for Eu(III) red emission. Linear working curves were obtained within a wide working region of 0-100 μM, with LOD of 1.7 μM. A short response time of 192 s at 25 °C was confirmed. Practical sensing plates were prepared and found applicable for VC detection in fresh human serum. The advantage of this work was the combination of a pre-oxidized probe and a porous host which gave emission "turn on" fluorescence sensing for VC with good selectivity, linear calibration curve and wide working region.
抗坏血酸（俗称维生素 C，VC）是人体中必需的抗氧化剂和自由基清除剂。可靠的荧光纳米传感器的需求不断推动 VC 探针的发展。在这项工作中，合成了预氧化的 Eu 探针（表示为 Eu-NO）。在没有 VC 的情况下，由于配体能级不匹配和距离 Eu 离子较远，导致配体向 Eu 离子的能量转移（ET）效率较低（单晶分析和发射参数揭示），Eu-NO 几乎没有发光。通过添加 VC，预氧化的配体被还原，其向 Eu 离子的 ET 变得高效（通过电化学分析证实），Eu(III)红色发射强度明显增加。然后，Eu-NO 被掺杂到多孔生物 MOF-1 中用于检测抗坏血酸（表示为 Eu-NO@MOF）。生物 MOF-1 的分子筛效应提高了传感选择性，生物 MOF-1 的蓝色发射（421nm）被用作 Eu(III)红色发射的参考。在 0-100μM 的宽工作范围内获得了线性工作曲线，LOD 为 1.7μM。在 25°C 下确认了 192s 的短响应时间。制备了实用的传感板，并发现其适用于新鲜人血清中 VC 的检测。这项工作的优点是预氧化探针和多孔主体的结合，为 VC 提供了良好选择性、线性校准曲线和宽工作范围的发射“开启”荧光传感。
