Cy5.5 Picolyl Azide is a bright and photostable near-IR dyes that is spectrally similar to Alexa Fluor® 680, DyLight® 680, and IRDye® 680 dye. The Cy5.5 Picolyl Azide is water-soluble, hydrophilic dye often a reagent of choice for assay where minimal non-specific binding is required. Cy5.5 Picolyl Azide is pH insensitive from pH 4 to pH 10 and produces minimal autofluorescence of biological specimens in this region of the spectrum. Fluorescence of this long-wavelength Cyanine dye is not visible to the human eye but is readily detected by most imaging systems.
Cy5.5 Picolyl Azide is an advanced fluorescent probe that incorporates a copper-chelating motif to raise the effective concentration of Cu(I) at the reaction site. The rate of CuAAC reaction depends on concentrations of all reagents, including copper, thus the raise of the effective copper concentration at the reaction site dramatically increase the rate of CuAAC reaction without the need to increase concentration of azide reagent and copper.
In addition, the use of Cy5.5 Picolyl Azide instead of conventional Cy5.5 Azide allows for at least a tenfold reduction in the concentration of the copper catalyst without sacrificing the efficiency of labeling.