Small-molecule thiols are essential for maintaining the cellular redox homeostasis and play important roles in regulating various cellular functions. New reaction-based fluorescent turn-on probes based on fast thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole)ether were rationally designed for sensing of biothiols in physiological buffer and in cells. The blue-light-excited probes were based on a new developed excited-state intramolecular proton transfer (ESIPT) fluorophore. The combination use of ESIPT fluorophore and electron-withdrawing effect in the probe design led to fast-response fluorescent probes toward cysteine (Cys) with reaction rate (k ₂) up to 616.7M⁻¹ s⁻¹. The probes were highly selective toward biothiols over other amino acids and could be used for bioimaging in cells.

中文翻译：

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基于快速响应NBD的生物硫醇荧光探针的合理设计和合成

小分子硫醇对于维持细胞氧化还原稳态是必不可少的，并且在调节各种细胞功能中起重要作用。合理设计了基于NBD（7-硝基-1,2,3-苯并恶二唑）醚快速硫解的基于反应的新型荧光开启探针，用于感测生理缓冲液和细胞中的生物硫醇。蓝光激发探针基于新开发的激发态分子内质子转移（ESIPT）荧光团。探针设计中结合使用ESIPT荧光团和吸电子效应，导致对半胱氨酸（Cys）的快速响应荧光探针，反应速率（k ₂）高达616.7M ^-1 s ^-1。该探针对生物硫醇的选择性高于其他氨基酸，可用于细胞中的生物成像。