CF®640R is a rhodamine-based far-red fluorescent dye with excitation and emission maxima similar to those of Cy®5 and Alexa Fluor® 647 (Figure 1). CF®640R is much brighter than Cy®5 and at least as bright as Alexa Fluor® 647 (Figure 2). A major advantage of CF®640R over Cy®5 and Alexa Fluor® 647 is its exceptional photostability (Figures 3 and 4). Cy®5 and Alexa Fluor® 647 are cyanine-based dyes and, like other cyanine dyes in general, have intrinsically poor photostability by comparison.
CF®640R is also superior to ATTO 647N, another spectrally similar dye frequently used in single-molecule imaging. As shown in Figure 2, CF®640R yields much brighter antibody conjugates than the ATTO dyes. Due to its high water solubility, CF®640R can label proteins to a high degree of labeling without quenching, unlike the ATTO dyes.
The combination of excellent brightness and photostability makes CF®640R ideal for confocal microscopy, single- molecule imaging and other demanding applications based on fluorescence detection. CF®640R also is compatible with super-resolution imaging by TIRF and FLIMP (learn more about CF® Dyes for Super-Resolution Microscopy).
CF®640R Technical Summary
- Abs/Em maxima: 642/662 nm
- Extinction coefficient: 105,000
- Molecular weight: ~832
- Excitation laser line: 633, 635 or 640 nm
- Alternative for: Alexa Fluor® 647, ATTO 647N, Cy®5, DyLight® 649
- Fluorescence lifetime:
τ (ns)/free acid in PBS pH 7.4, ε (ns) = 2.38 ± 0.05
τ (ns) /S.Ab§ = 1.557
Visit our FAQ for more fluorescence life time information on CF® dyes.
CF®640R Features
- The best photostability among Cy®5-like dyes
- Yields highly fluorescent protein conjugates
- Water-soluble and pH-insensitive
- Compatible with TIRF and FLIMP super-resolution imaging
CF is a registered trademark of Biotium Inc. Alexa Fluor and DyLight are registered trademarks of Thermo Fisher Scientific; Cy Dye is a registered trademark of Cytiva.