Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang, 330013, PR China.
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang, 330013, PR China.
Anal Chim Acta. 2024 Nov 15;1329:343193. doi: 10.1016/j.aca.2024.343193. Epub 2024 Sep 1.
Cys, as an essential amino acid that can be ingested from daily food, plays an important role in maintaining the oxidative balance in cells. Abnormal Cys levels in organisms will lead to various diseases. Therefore, it is of great significance to construct a fluorescent probe that can detect Cys levels in food and biological systems.
Here, a turn-off type probe TA had been successfully synthesized, which attached diethylamine as the strong electron donor, acrylate as the weak electron donor, and xanthene as the π-bridge. TA showed wonderful selectivity, low detection limit, good photostability and well live-cell compatibility for Cys by reducing acrylate group to hydroxyl group of TAOH. The reaction mechanism was demonstrated by H NMR, ESI-MS spectra, pH-dependent response experiments, and DFT calculations. Importantly, the reason why TAOH exhibited no fluorescence was the disappearance of the ICT effect in the molecule due to the dominant existence of spirocyclic state of TAOH. In addition, the probe can be used not only for the imaging detection of Cys in A549 cells and zebrafish, but also for the detection of Cys levels in food samples.
This work provides a new idea for the design of Cys fluorescent probe, which may be beneficial to the comprehension of the potential mechanism of novel fluorescent probe.
半胱氨酸（Cys）作为一种可以从日常食物中摄取的必需氨基酸，在维持细胞氧化平衡方面起着重要作用。生物体中异常的 Cys 水平会导致各种疾病。因此，构建一种能够检测食物和生物体系中 Cys 水平的荧光探针具有重要意义。
本文成功合成了一种关闭型探针 TA，它通过将丙烯酰胺基团还原为 TAOH 的羟基，附着二乙胺作为强电子供体、丙烯酰胺作为弱电子供体、以及呫吨作为π桥。TA 对 Cys 表现出极好的选择性、低检测限、良好的光稳定性和良好的活细胞兼容性。该反应机制通过 H NMR、ESI-MS 谱、pH 依赖性响应实验和 DFT 计算得到了证明。重要的是，TAOH 没有荧光的原因是由于 TAOH 分子中螺旋环状态的主导存在，导致 ICT 效应消失。此外，该探针不仅可用于 A549 细胞和斑马鱼中 Cys 的成像检测，还可用于检测食物样品中的 Cys 水平。
这项工作为 Cys 荧光探针的设计提供了一个新的思路，可能有助于理解新型荧光探针的潜在机制。
