“…Moreover, although the ratiometric uorescence sensing of these bioactive molecules in the whole cell, cytoplasm, and mitochondria has been widely explored, 19,31,32 it is still a challenging task to trace their ux in the nucleus. Indeed, the rare examples only include nuclearlocalized probes NucPE1, SNAP-PG and a highly sensitive probe NP1 responding to the changes of nuclear H 2 O 2 uxes, [33][34][35] a photo-stable pH probe NaOCy and a ratiometric uorescence pH probe hoeFL for selectively staining nuclei in living cells; 36,37 a sulfur-containing uorogenic probe JG45 for selectively detecting nuclear methylmercury (MeHg 2+ ). 38 The difficulty in visualizing the ux of bioactive molecules in the nucleus is mainly due to the impermeable nuclear membrane and the interference of the complex nucleic acid environment with the uorescence of probes.…”