Herein, a novel ratiometric fluorescent probe based on CDs@Eu/GMP ICP nanoparticles was developed for the detection of Aβ monomer in rat as a biomarker for Alzheimer's disease (AD) by fully exploring the competitive coordination interaction and by taking advantage of excellent optical property of carbon dots sensitized lanthanide infinite coordination polymer (ICP) nanoparticles. The carbon dots (CDs) with abundant functional groups were encapsulated into Eu/GMP ICPs through self-adaptive chemistry, which could not only sensitize the red fluorescence of Eu/GMP ICPs effectively, but also act as an internal reference for self-correction. In the absence of Cu2+, the as-formed CDs@Eu/GMP ICPs exhibited the characteristic emission of CDs at 400 nm and strong emission of Eu3+ at 592 nm, 615 nm, 650 nm and 694 nm. With the addition of Cu2+, the red fluorescence of Eu3+ decreased due to the coordination interaction between CDs and Cu2+, thus destroyed the antenna effect. After the subsequent addition of Aβ monomer, the specific binding occurred between Cu2+ and Aβ monomer, and then the red fluorescence of Eu3+ restored again. During this process, the fluorescence of CDs remained unchanged, thus could be used as an internal reference to cancel out the environmental fluctuation and was more adaptive for the detection of Aβ monomer in biological fluids. The method demonstrated here was highly sensitive, free from the interference of other species in rat brain, the in vivo analysis of Aβ monomer in CSF and different brain regions from normal rats and Alzheimer's rats could be realized, which was of great significance for better understanding the mechanism of AD and paving the way to understand the chemical essence involved in AD.

中文翻译：

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碳点敏化镧系元素无限配位聚合物纳米粒子：将脑脊髓 Aβ 单体作为阿尔茨海默病生物标志物的比率荧光传感

在此，基于CDs@Eu/GMP ICP纳米颗粒的新型比率荧光探针通过充分探索竞争配位相互作用并利用优异的光学特性，开发了用于检测大鼠Aβ单体作为阿尔茨海默病（AD）的生物标志物碳点敏化镧系元素无限配位聚合物 (ICP) 纳米粒子。通过自适应化学将具有丰富官能团的碳点（CDs）封装到Eu/GMP ICPs中，不仅可以有效地敏化Eu/GMP ICPs的红色荧光，还可以作为自我校正的内参。在没有 Cu2+ 的情况下，形成的 CDs@Eu/GMP ICPs 在 400 nm 处表现出 CDs 的特征发射和在 592 nm、615 nm、650 nm 和 694 nm 处的 Eu3+ 强发射。随着 Cu2+ 的加入，由于CDs和Cu2+之间的配位相互作用，Eu3+的红色荧光减弱，从而破坏了天线效应。随后加入Aβ单体后，Cu2+与Aβ单体发生特异性结合，Eu3+红色荧光再次恢复​​。在此过程中，CDs的荧光保持不变，可作为抵消环境波动的内参，更适合生物体液中Aβ单体的检测。该方法灵敏度高，不受其他物种对大鼠脑组织的干扰，可实现对正常大鼠和阿尔茨海默病大鼠脑脊液和不同脑区Aβ单体的体内分析，