Photostable red turn-on fluorescent diketopyrrolopyrrole chemodosimeters for the detection of cysteine in living cells

A new red fluorescent “turn-on” diketopyrrolopyrrole (DPP)-based chemodosimeter DPP-DNBS for the detection of cysteine was developed, in which DPP-DNBS was constructed by DPP fluorophore connected to a 2,4-dinitrobenzenesulfonyl (DNBS). The specific reaction between biological thiols and DPP-DNBS gave rise to an obvious fluorescence intensity enhancement at 615nm which was induced by the cleavage of OS bond liberates DPP fluorophore. Moreover, DPP-DNBS was also employed in cellular detection of cysteine and realized discrimination of cysteine from homocysteine and glutathione in Hela cells. •Diketopyrrolopyrrole-based chemodosimeter DPP-DNBS for cysteine was developed.•Sensing mechanism was proved to be cleavage of OS bond by cysteine.•DPP-DNBS gave a red emission signal with good stability.•DPP-DNBS achieved “off-on” fluorescent signal for intracellular detection of Cys. The optical monitoring of thiols such as glutathione (GSH), cysteine (Cys) and homocysteine (Hcy) is of significant interest due to their crucial roles in maintaining the biological redox homeostasis through the equilibrium of free thiols and oxidized disulfides in biological systems. In this work, a molecular chemodosimeter DPP-DNBS with a highly photostable diketopyrrolopyrrole (DPP) fluorophore connected to a 2,4-dinitrobenzenesulfonyl (DNBS) electron-withdrawing group for selective detection of biothiols was effectively synthesized. The specific reaction between biological thiols and DPP-DNBS gives rise to an obvious fluorescence intensity enhancement at 615nm which is induced by the cleavage of OS bond liberates DPP fluorophore. High sensitivity and selectivity for pathless over other amino acids were also obtained. Moreover, via turn-on signal toward cysteine in Hela cells, DPP-DNBS was also employed in cellular detection of cysteine and realized discrimination of cysteine from homocysteine and glutathione in Hela cells.