State Key Laboratory of Chemo/Bio-sensing & Chemometrics, College of Chemistry & Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China.
Methods Appl Fluoresc. 2017 Mar 22;5(1):014012. doi: 10.1088/2050-6120/aa6160.
Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5'-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system. After specifically reacted with Cys, the probe undergoes a seven-membered intramolecular cyclization and released the fluorophore CHCQ with excited-state intramolecular photon transfer effect. A highly fluorescent, insoluble aggregate was then formed to facilitate high-sensitivity and high-resolution imaging. The results showed that probe CHCQ-Ac affords a remarkably large Stokes shift and can detect Cys under physiological pH condition with no interference from other analytes. Moreover, this probe was proved to have excellent chemical stability, low cytotoxicity and good cell permeability. Our design of this probe provides a novel potential tool to visualize and localize cysteine in bioimaging of live cells that would greatly help to explore various Cys-related physiological and pathological cellular processes in cell biology and diagnostics.
小分子探针适用于选择性和特异性荧光成像一些重要但低浓度的细胞内活性硫物种，如半胱氨酸（Cys），在化学生物学中构成了挑战。我们提出了一种易于获得、快速响应的荧光探针 CHCQ-Ac，其荧光团为 2-（5'-氯-2-羟基-苯基）-6-氯-4(3 H)-喹唑啉酮（CHCQ），功能部分为丙烯酰胺基，能够在溶液和生物体系中高选择性和高灵敏度地检测 Cys。与 Cys 特异性反应后，探针经历七元环分子内环化，释放出具有激发态分子内光子转移效应的荧光团 CHCQ。然后形成高度荧光的不溶性聚集体，以实现高灵敏度和高分辨率成像。结果表明，探针 CHCQ-Ac 具有显著的斯托克斯位移，可以在生理 pH 条件下检测 Cys，不受其他分析物的干扰。此外，该探针还被证明具有优异的化学稳定性、低细胞毒性和良好的细胞通透性。我们设计的这种探针为在活细胞的生物成像中可视化和定位半胱氨酸提供了一种新的潜在工具，这将极大地有助于探索细胞生物学和诊断学中各种与 Cys 相关的生理和病理细胞过程。
