Novel fluorophores for fluorescent
ion indicators incorporate water-solubilizing functional groups. These fluorophores enable visible-
wavelength analysis of
ion concentrations with chelators that are insoluble or poorly soluble in water. A green version of the
fluorophore comprises a putative
fluorescein with
carboxylate appendages. An orange version of the
fluorophore comprises a putative
rhodamine, also with
carboxylate appendages. Attaching the
fluorophore to a 12-crown-4, a 15-crown-5, a 18-crown-6, a 21-crown-7, or a 24-crown-8 produces
lithium,
sodium,
potassium,
rubidium, and cesium indicator families, respectively. Attaching the fluorophore to diaza [1,1,1], [1,1,2], [1,2,2], [2,2,2], [2,2,3], [2,3,3], or [3,3,3] cryptands produces more selective
lithium,
sodium,
potassium,
rubidium, and cesium indicator families, respectively. Attaching the fluorophore to
BAPTA, APTRA, or half-
BAPTA or their analogs produces new
calcium,
magnesium, and other
metal ions indicator families that strongly
resist leakage from the
cell.