A turn-on fluorescent probe via substitution-rearrangement for highly sensitive and discriminative detection of cysteine and its imaging in living cells

Biothiols play an important role in many physiological and pathological processes, especially in the occurrence of oxidative stress caused by abnormal cysteine (Cys) concentration. Therefore, it is particu-larly critical to develop a method that can specifically identify Cys to avoid interference from other bio-logical analytes. However, most Cys-specific fluorescent probes are difficult to distinguish between homocysteine (Hcy) and glutathione (GSH). In this work, to avoid the interference of Hcy and GSH, we developed a fluorescent probe triarylimidazole-naphthalimide-piperazine-sulfonyl benzoxadiazole (TNP-SBD-Cl) based on fluorescence resonance energy transfer (FRET) on platform of naphthalimide-sulfonyl benzoxadiazole (SBD), the main SBD 4-chlorine groups have mild reactivity to undergo substitution and rearrangement to distinguish Hcy and GSH. The TNP-SBD-Cl response to Cys would turn on FRET and generate a new yellow fluorescence with a large Stokes shift (157 nm), and with excellent selectivity and low detection limit (0.87 mu M). Moreover, TNP-SBD-Cl can be used to monitor Cys in living HeLa cells with low cytotoxicity, suggesting that it has markedly diagnostic significance in physiological and patho-logical processes. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, a fluorescent probe TNP-SBD-Cl was developed to specifically identify cysteine (Cys) and avoid interference from other biological analytes. The probe can monitor Cys in living HeLa cells with low cytotoxicity, showing significant diagnostic potential in physiological and pathological processes.