Sulfo-Cyanine5.5 (analog of Cy5.5?) is a water-soluble, far red emitting fluorophore. Due to four sulfo-groups, the dye possesses negative charge in neutral pH, and very high hydrophilicity._x000D_
As a cyanine dye, sulfo-Cyanine5.5 shows very low dependence of the fluorescence on pH, and very high extinction coefficient.
