Cy7 maleimide is a near-infrared, sulfhydryl reactive dye which has low aqueous solubility. This reagent can label the proteins contain free sulfhydryl groups. Labeled proteins thus obtained are used in NIR bioimaging applications. In tissues or in live organism, NIR imaging systems can be used to visualize distribution of labeled proteins. 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.
