A regenerated "turn on" fluorescent probe for sulfide detection in live cells and read samples based on dihydroxyhemicyanine-Cu 2+ dye.

A novel "turn-on" fluorescence probe (HHC)2 -Cu2+ for sulfide (S2- ) was synthesized and characterized based on dihydroxyhemicyanine-Cu2+ complex. The probe displayed high sensitivity and selectivity for S2- over other analytes, including biothiols, NaCN, reactive oxygen species (ROS) and reactive nitrogen species (RNS) in aqueous solution, which was attributed to the large association constant and the fast kinetics of precipitation of CuS. The probe (HHC)2 -Cu2+ can be regenerated and reversibly detected with S2- with a remarkable red-fluorescent change by alternating the addition of S2- and Cu2+ . Fluorescent spectra of (HHC)2 -Cu2+ toward S2- showed a high selectivity, a good linearity, a low limit of detection at 0.12 μM, a rapid response time (less than 30 s), and a wide pH range of 7-10. Importantly, the probe was successfully applied to detect the low level of S2- in waste water samples, corrupt blood samples, and living cells.