Cy5.5 maleimide is a thiol reactive dye which is capable of selective labeling of proteins which contain sulfhydryl groups. Cy5.5 maleimide has near infrared emission that makes it suitable for bioimaging applications. This reagent can replace Alexa Fluor 680 and DyLight 680. For biomolecule labeling, the labeling reagent has low aqueous solubility, using of organic co-solvent to dissolve this molecular is necessary for efficient reaction. First, Cyanine dye should be dissolved in organic solvent and then added to a solution of biomolecule in appropriate aqueous buffer.
