Rapid detection of hypochlorite by a coumarin-based hydrazide in aqueous solution and its application in live-cell imaging

By employing the oxidation property of hypochlorite (OCl − ), a new probe based on coumarin dye and an OCl − -specific reactive moiety of hydrazide group was designed and synthesized. The probe rendered turn-on type fluorogenic response toward OCl − via hypochlorite-triggered oxidative hydrolysis of hydrazide to release strongly fluorescent coumarin. Most notably, the probe showed sufficiently satisfactory selectivity to OCl − over other oxidants, and high sensitivity with approximate 18-fold fluorescence enhancement at nanomolar level. Moreover, the fast detection of OCl − could be realized by the probe with only 30   s. The interaction mechanism has been proposed and further confirmed by the changes in electrospray ionization (ESI) mass spectra. The probe was also successfully applied to fluorescence imaging of OCl − in its vitro macrophage cells.