Cysteine (Cys) as a vital antioxidant molecule and an effective biomarker for illness, plays an essential role in physiological functions and pathological processes. Extensive work has been done to explore the physiological functions of Cys and develop probes for detection of biothiols. However, the challenge to differentiate Cys from glutathione and homocystine remains. In this work, we constructed a novel near-infrared (NIR) probe, termed TMN-Cys, using TMN-NH₂ and thionoesters. The probe could selectively detect Cys over homocysteine and glutathione in solution. It displayed a large Stokes shift (210 nm) upon treatment with Cys, and its detection limit was as low as 79 nM. Moreover, this probe showed low toxicity and was successfully employed in monitoring endogenous Cys in living cells and mice.

半胱氨酸（Cys）作为重要的抗氧化剂分子和疾病的有效生物标记物，在生理功能和病理过程中起着至关重要的作用。已经进行了广泛的工作以探索Cys的生理功能并开发用于检测生物硫醇的探针。然而，区分Cys与谷胱甘肽和高半胱氨酸的挑战仍然存在。在这项工作中，我们使用TMN-NH ₂构建了一种新型的近红外（NIR）探针，称为TMN-Cys。和硫代酸酯。该探针可以选择性检测溶液中同型半胱氨酸和谷胱甘肽上的半胱氨酸。用Cys处理后显示出大的斯托克斯位移（210 nm），其检测限低至79 nM。此外，该探针显示出低毒性，并成功地用于监测活细胞和小鼠中的内源性半胱氨酸。