An efficient fluorescent probe for rapid sensing of different concentration ranges of cysteine with two-stage ratiometric signals

Abstract

A diketopyrrolopyrrole-based fluorescent probe (DPP-AC) for rapid sensing of different concentration ranges of cysteine (Cys) has been designed and synthesized, where acrylate group and α,β-unsaturated ketone moiety on DPP-AC are employed as the high and low sensitivity sites, respectively. On the basis of proposed strategy, probe DPP-AC showed ratiometric fluorescent change from 605 nm to 578 nm in presence of low concentration of Cys because of the conjugate addition-cyclization-elimination sequence reaction of acrylate group of DPP-AC with Cys. The addition of excess Cys caused second stage of ratiometric fluorescent change from 578 nm to 560 nm, which due to the Michael addition reaction between α,β-unsaturated ketone of DPP-AC and Cys. Moreover, different concentration ranges of cysteine detection can be completed in 6 min at room temperature. The limit of detection (LOD) was found to be 0.18 μM and 2.9 μM in less and excess Cys ranges, respectively. Furthermore, probe DPP-AC possessed highly selective property to differentiate Cys over glutathione and homocysteine. DPP-AC was also successfully used in cell imaging.