Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play many crucial physiological roles in organisms. Their abnormal levels can cause and indicate various diseases. In the present study, a small-molecule fluorescent probe 2-(imidazo[1,2-a]pyridin-2-yl)phenyl acrylate (IPPA) was designed, synthesized and characterized by NMR, FT-IR and HRMS. IPPA can selectively detect Cys over other analytes because of an approximately 76 times enhancement in fluorescence intensity. The limit of detection of IPPA for Cys was 0.33 μM. The pseudo-first-order rate constant of the reaction between IPPA and Cys was approximately 10 times that of the reaction between IPPA and Hcy (KCys 3.18 × 10-3 S-1vs KHcy 4.92 × 10-4 S-1), indicating that Cys can be distinguished from Hcy. In addition, IPPA exhibits strong anti-interference ability, small molecular weight, high efficiency, low toxicity and good cell permeability. It was successfully used in imaging HepG2 cells and zebrafish. The fluorescence response of IPPA for calf serum are powerful proofs for practical application. Therefore, IPPA has high potential for bioassay applications.

中文翻译：

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一种新颖且简单的咪唑并[1,2-a]吡啶荧光探针，用于活细胞和斑马鱼中半胱氨酸的灵敏和选择性成像

半胱氨酸 (Cys)、同型半胱氨酸 (Hcy) 和谷胱甘肽 (GSH) 在生物体中发挥着许多重要的生理作用。它们的异常水平会导致和预示各种疾病。本研究设计、合成了小分子荧光探针2-(咪唑并[1,2-a]吡啶-2-基)丙烯酸苯酯(IPPA)，并通过NMR、FT-IR和HRMS进行了表征。与其他分析物相比，IPPA 可以选择性地检测 Cys，因为荧光强度增强了约 76 倍。IPPA 对 Cys 的检测限为 0.33 μM。IPPA 和 Cys 之间的反应的准一级速率常数约为 IPPA 和 Hcy 之间的反应的 10 倍 (KCys 3.18 × 10-3 S-1 vs KHcy 4.92 × 10-4 S-1)，表明Cys 可以与 Hcy 区分开。此外，IPPA具有抗干扰能力强、分子量小、效率高、毒性低、细胞渗透性好等优点。它已成功用于 HepG2 细胞和斑马鱼的成像。IPPA对小牛血清的荧光响应是实际应用的有力证明。因此，IPPA在生物测定应用中具有很大的潜力。