A colorimetric fluorescent chemodosimeter based on diketopyrrolopyrrole and 1,3-indanedione for cysteine detection and cellular imaging in living cells

A novel colorimetric fluorescent chemodosimeter (1) based on diketopyrrolopyrrole (DPP) and indanedione for the selective detection of cysteine (Cys) over glutathione (GSH) was synthesized, which was involved by the conjugate addition of Cys to α,β-unsaturated ketones. The probe featured a fast response (a response time less than 2 min), excitation and emission in the visible region, dual-channel and high selectivity. Addition of Cys in PBS (pH = 7.4) to 1 in THF resulted in a rapid color change from purple to yellow together with appearance of a new absorption peak at 480 nm, while other amino acids did not induce any significant color change. Meanwhile, the Michael addition of Cys to 1 elicited 4.2-fold PL enhancement at 505 nm, which resulted in emission color change from deep red to yellow. Furthermore, 1 could be used as a fluorescent probe for detection Cys34 within BSA. In addition, the cellular imaging of human adult skin fibroblast cells indicated red fluorescence of 1 was present in the cytoplasm. The CCK-8 assay showed that the cytotoxicity of 1 was low.