Diketopyrrolopyrrole-based ratiometric fluorescent probe for the sensitive and selective detection of cysteine over homocysteine and glutathione in living cells

A new fluorescent probe ( DPP-AC ) based on diketopyrrolopyrrole with an acrylate group was designed and synthesized for the sensitive and selective detection of biological thiols. The acrylate group of DPP-AC as the receptor moiety displayed obvious ratiometric changes from red to yellow upon the addition of cysteine (Cys), and the change in fluorescence ratio ( I 552 / I 664 ) was over 20-fold. The limit of detection towards Cys was calculated as 84 nM; much lower than the normal concentration in living cells. More importantly, DPP-AC had outstanding selectivity towards cysteine over homocysteine (Hcy), glutathione (GSH) and other amino acids. DPP-AC was successfully employed to detect endogenous Cys in Hela cells and discriminate Cys from Hcy and GSH in living cells. A new fluorescent probe ( DPP-AC ) based on diketopyrrolopyrrole with an acrylate group was designed and synthesized for the sensitive and selective detection of biological thiols.