sulfo-Cyanine7.5 is a very hydrophilic and water-soluble dye for the near-infrared region. The absorption and emission spectra of the dye are similar to Indocyanine Green (ICG), but sulfo-Cyanine7.5 has a much higher fluorescence quantum yield. The dye is a great choice for near-infrared in vivo imaging. This is an azide for click chemistry.