Cy5.5 dyes are among the most widely used fluorescent labels for preparing NIR fluorescent bioconjugates. Cy5.5 conjugates are very bright, photostable, and pH insensitive and produce minimal autofluorescence of biological specimens in this region of the spectrum. With a peak excitation at 678 nm and a maximum emission at 694 nm, Cy5.5 is spectrally almost identical to other near-IR dyes, including DyeLight 680™, IRDye™ 680 dye, and Alexa Fluor™ 680, and is ideal for multi-color applications.
This sulfonated dye is also known as sulfo-Cyanine5.5 NHS ester. Cy®Dye is a trademark of GE Healthcare.