Cysteine (Cys) takes part in redox balance in cells as an antioxidant, and imbalance of Cys content in the body can cause a variety of diseases. It is very important to develop a new fluorescent chemosensor to specifically detect Cys intracellular. In this work, a novel NIR fluorescent probe was constructed based on 3-ethyl-1,1,2-trimethyl-1H-benzo[e]indol-3-ium iodide and 5-(4-hydroxyphenyl)furan-2-carbaldehyde. The probe could selectively detect Cys in the presence of homocysteine (Hcy), glutathione (GSH), and other interferences. It also had a number of advantages, including nucleolus-targeting ability, long fluorescence emission wavelength (685 nm), low detection limit (56 nM), and large Stokes shift (172 nm). The probe was employed to enable visualization of Cys in HepG2 cells, and due to its good response in viscous environment, the probe could also locate nucleoli intracellular.

半胱氨酸（Cys）作为抗氧化剂参与细胞中的氧化还原平衡，体内Cys含量不平衡会导致多种疾病。开发一种新的荧光化学传感器以特异性检测胞内Cys非常重要。在这项工作中，基于3-乙基-1,1,2-三甲基-1H-苯并[e]吲哚-3-碘化碘和5-（4-羟苯基）呋喃-2-甲醛构建了一种新型的近红外荧光探针。 。该探针可以在同型半胱氨酸（Hcy），谷胱甘肽（GSH）和其他干扰物存在下选择性检测Cys。它还具有许多优势，包括核仁靶向能力，长荧光发射波长（685 nm），低检测限（56 nM）和大斯托克斯频移（172 nm）。该探针用于使HepG2细胞中的Cys可视化，并且由于其在粘性环境中的良好响应，