Cy5 Azide (also sold under the Sulfo-Cyanine5 Azide name) is a water-soluble, bright, far-red-fluorescent probe with excitation ideally suited for the 633 nm or 647 nm laser lines. A significant advantage to using long wavelength dyes such as Cy5 or AF 647 dye over other fluorophores is the low autofluorescence of biological specimens in this region of the spectrum.
Cy5 Azide can be reacted with terminal alkynes via a copper-catalyzed click reaction (CuAAC). It also reacts with strained cyclooctyne via a copper-free “click chemistry” reaction to form a stable triazole and does not require Cu-catalyst or elevated temperatures.
For the detection of low abundance targets or where significant increase in signal intensity is desired please consider using next generation azides probes containing an internal copper-chelating motif.