Forte Blue� DHPE is a phospholipid that is labeled on the head group with the bright, blue-fluorescent Forte Blue� dye. Forte Blue� DHPE is optimally excited by the intense 365 nm spectral line of the mercury-arc lamp/UV lasers, and exhibits bright blue fluorescence emission near 460 nm. Significantly, the low pKa value of this newly developed 7-hydroxycoumarin derivative is 2�3 log units lower than that of the parent 7-hydroxycoumarin analogs. Forte Blue� DHPE is expected to be stro
ngly fluorescent in membranes, even at neutral pH.