4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene as a bright fluorescent label for DNA.

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) as a fluorescent label can be incorporated into DNA by two conceptually different ways: the non-nucleosidic DNA base surrogate Bo exhibits high brightness but no preferential base-pairing properties, whereas the BODIPY-modified uridine BodU has reduced quantum yields but shows preferred Watson-Crick base pairing with adenine.