Far-red fluorescent dyes offer the advantage of ultra sensitive detection because background signal due to autofluorescence in most biological samples is minimal in this spectral region. For many years, the cyanine dye Cy®5 has been the dye of choice for such detection. More recently, Alexa Fluor® 647 has been developed as a better alternative by having brighter fluorescence and higher photostability. Despite the improvement, Alexa Fluor® 647 still lacks sufficient photostability required for many demanding applications. On the other hand, while Alexa Fluor® 633 is photostable, its fluorescence on proteins is very weak.
In fact, it has been a challenging task for dye chemists to develop a far-red fluorescent dye that is both highly fluorescent and photostable for protein and nucleic acid labeling. Using new chemistry, scientists at Biotium have successfully developed CF™633 to overcome these challenges. With its absorption peak at 630 nm, CF™633 is optimally excited by the 633 nm He-Ne laser or the 635 nm red diode laser. Its emission maximum is at 650 nm, which is 15 nm shorter than that of Alexa Fluor® 647 or Cy®5. Although the detection window on most flow cytometers is centered around the emission peak wavelength of Alexa Fluor® 647 or other Cy®5-like cyanine dyes, CF™633 is still significantly brighter (Figure 2).
The most important advantage of CF™633, however, is its unmatched photostability (Figure 3). The combination of superior brightness and photostability make CF™633 the best choice for any detection system using a 633 or 635 nm laser excitation source.
A full selection of reactive dyes, secondary antibodies, antibody labeling kits, and other bioconjugates including phalloidins, Annexin V and α-bungarotoxin are available for CF™ dyes.