The growing evidence suggests that the disturbance of redox homeostasis in the brain tissue contributes to the process of tissue damage following ischemic stroke (IS). Tracking redox process in situ is critical for diagnosis, treatment and drug design of IS. Monitoring of substances in the reduction system is more suitable than detection of molecules of oxidation system, such as reactive oxygen species (ROS), due to their difficult capture of fleeting existence. Glutathione (GSH), a dominated component of reduction system, has higher concentration than other reduced substances and is the major cellular antioxidant for maintaining the redox balance but dramatically decreases during cerebral ischemia. Efficient tools can realize the real-time tracing of endogenous GSH at ultra low concentration during ischemic damage are significant and indispensable for dynamic monitoring the process of IS. Till now, only a few fluorescent probes have been reported for imaging GSH. The direct visualization of reductive substances in the cerebral vasculature of live mice is still a significant challenge. More importantly, due to the presence of the blood–brain barrier (BBB), monitoring GSH at ultralow concentration in brain tissue seems more difficult, which tremendously restricts the development of new strategies for targeting, detecting, and imaging GSH in vivo. In present study, we successfully synthesized a series of BODIPY-based fluorescent probes, WD-1-SH, WD-2-SH, and WD-3-SH, and detected many properties, including the capacity to penetrate the BBB, sensitivity to GSH and tissue penetration depth of excitation, and emission wavelengths. In vitro experiments revealed that among the probes, WD-1-SH exhibited the highest sensitivity to reducing substances; however, WD-2-SH exhibited higher sensitivity in vivo. These desired photophysical and pharmacokinetic properties endow our fluorescent probes with the capability to monitor brain tissue low concentration GSH after injury with excellent temporal and spatial resolution. Due to these favourable properties, our fluorescent probes hold great promise for visualizing endogenous reducing substances in a variety of pathophysiological processs in vitro and in vivo, such as during stroke induced ferroptosis.

越来越多的证据表明，脑组织中氧化还原稳态的紊乱有助于缺血性中风 (IS) 后的组织损伤过程。原位跟踪氧化还原过程对于 IS 的诊断、治疗和药物设计至关重要。监测还原系统中的物质比检测氧化系统分子更合适，例如活性氧 (ROS)，因为它们难以捕捉短暂的存在。谷胱甘肽（GSH）是还原系统的主要成分，其浓度高于其他还原物质，是维持氧化还原平衡的主要细胞抗氧化剂，但在脑缺血期间显着降低。高效的工具可以实现对缺血性损伤过程中超低浓度内源性GSH的实时追踪，对于动态监测IS过程意义重大且不可或缺。到目前为止，只有少数荧光探针被报道用于 GSH 成像。活鼠脑血管中还原物质的直接可视化仍然是一项重大挑战。更重要的是，由于血脑屏障 (BBB) 的存在，在脑组织中以超低浓度监测 GSH 似乎更加困难，这极大地限制了靶向、检测和成像 GSH 的新策略的发展在体内。在本研究中，我们成功合成了一系列基于 BODIPY 的荧光探针WD-1-SH、WD-2-SH和WD-3-SH，并检测到了许多特性，包括穿透 BBB 的能力、对激发和发射波长的 GSH 和组织穿透深度。体外实验表明，在这些探针中，WD-1-SH对还原性物质的敏感性最高；然而，WD-2-SH在体内表现出更高的灵敏度. 这些所需的光物理和药代动力学特性使我们的荧光探针能够在损伤后以出色的时间和空间分辨率监测脑组织低浓度 GSH。由于这些有利的特性，我们的荧光探针有望在体外和体内的各种病理生理过程中可视化内源性还原物质，例如在中风诱导的铁死亡期间。