CF®660C & CF®660R

CF®660C and CF®660R are two spectrally similar fluorescent dyes that emit fluorescence at about 685 nm in the borderline spectral region between far-red and near-IR (Figure 1). Although their absorption maxima are at around 660 nm, both dyes can be sufficiently excited by the 633 or 635 nm laser. When combined with other CF® dyes of shorter wavelengths, CF®660C or CF®660R can serve as a useful long wavelength dye in multi-color detection applications. The two dyes are spectrally similar to Alexa Fluor® 660 but are far superior to the latter in performance.

Like Alexa Fluor® 660, CF®660C is a cyanine-based dye. However, when conjugated to protein, CF®660C is several fold brighter and significantly more photostable than Alexa Fluor® 660 (Figures 2 and 3). CF®660C is also validated in multi-color super-resolution imaging by STORM (learn more about CF® Dyes for super-resolution microscopy).

CF®660R is a rhodamine-based dye, and like rhodamine dyes in general, it is exceptionally photostable (Figure 3). CF®660R is also brighter than Alexa Fluor® 660 (Figure 2). The superior photostability and excellent brightness of CF®660R make the dye an ideal choice for confocal microscopy and other demanding applications.

CF®660C Technical Summary

Abs/Em maxima: 667/685 nm
Extinction coefficient: 200,000
Molecular weight: ~3112
Laser line: 633 or 635 nm
Direct replacement for: Alexa Fluor® 660, Allophycocyanin (APC)

CF®660R Technical Summary

Abs/Em maxima: 663/682 nm
Extinction coefficient: 100,000
Molecular weight: ~888
Laser line: 633 or 635 nm
Direct replacement for: Alexa Fluor® 660, Allophycocyanin (APC)

Visit our FAQ for more fluorescence lifetime information on CF^® Dyes.

Figure 1. Normalized absorption and emission spectra for CF®660C (solid lines) and CF®660R (dashed lines) goat anti-mouse conjugates in PBS.

Figure 2. CF®660C yields much brighter antibody conjugates than Alexa Fluor® 660. CF®660R also is brighter than Alexa Fluor® 660. Relative brightness of goat an... See More

Figure 3. CF®660 is extremely photostable. CF®660C also is more photostable than Alexa Fluor® 660. HeLa cells were stained with mouse anti-tubulin and goat anti... See More

Figure 4. Comparison of microtubule imaging using conventional wide-field microscopy with STORM using CF®660C conjugate. Images courtesy of Sam Kenny and Profes... See More

Helpful Tools & Resources

Spectra Viewer

Visualize and export the fluorescent dye spectrum of any CF® Dye or other dyes from Biotium.

Download Our CF® Dye eBook

Learn the history of fluorophores in life science research as well as the development and advantages of CF® Dyes.

CF® Dye Selection Tool

Check out our handy fluorophore selection tool to help choose the best CF® Dye for your next experiment.

CF® Dye Reference Guide

Download our single page reference guide for all CF® Dye fluorophores. Includes recommended channels, applications, relative brightness, and photostability.