NucPE1, a nuclear-localized fluorescent hydrogen peroxide, is specifically localized to cellular nuclei without appended targeting moieties.

NucPE1 exhibits two primary absorptions in the visible region (λabs=468 nm, ε=27,300 M-1cm-1; λabs=490 nm, ε=26,000 /(M·cm)) and a weak emission (λem=530 nm, Φ=0.117). The reaction of NucPE1 with H2O2 induces a fluorescence increase by converting it to fluorophore NucPE1, which shows a major absorption at 505 nm (ε=19,100 /(M·cm)) and enhanced emission (λem=530 nm, Φ=0.626). NucPE1 selectively accumulates in the nuclei of various mammalian cell lines and in whole model organisms like C. clegans, where it can detect subcellular H2O2 flux changes.

NucPE1 imaging reveals a reduction in nuclear H2O2 levels in worms overexpressing sir-2.1 compared to wildtype congeners.