Easy access of dihydrofluoresceins as advanced fluorescence turn-on probes for oxidative stress

A mild NABH(4)/I-2 strategy was designed to easily reduce fluoresceins to dihydrofluorescein alcohols and acids. Dihydrofluorescein alcohols exhibited surprisingly enhanced reactivity for oxidative stress sensing in comparison with the acid forms, using horseradish peroxidase/H2O2 as a model system for the generation of reactive radical species. Finally, two dual functional probes were then synthesized using our optimized reduction method, which showed great potentials for fluorescent imaging of subcellular oxidative stresses.