A ratiometric fluorescent probe for cysteine and its application in living cells

A ratiometric fluorescent probe DPCA based on coumarin and pyrazoline was designed and synthesized for sensing cysteine (Cys) in physiological pH. The probe can detect Cys by fluorescent spectrometry within 40   min with a detection limit of 5.08   μM. The mechanism of DPCA sensing Cys involved conjugate addition/cyclization which was confirmed by HRMS and fluorescence spectra analysis. Moreover, DPCA was able to be applied to complicated conditions with negligible interference from these species and successfully applied in cell imaging.