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CF®633 Dye

The best dye for 633/635 nm laser lines

Yeilds the brightest conjugates among spectrally similar dyes
Far more photostable than Alexa Fluor® 647
Validated in TIRF and other super-resolution methods

Figure 1. Normalized absorption and emission spectra of CF®633 goat anti-mouse conjugate in PBS.

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.

Using new chemistry, scientists at Biotium have successfully developed CF®633 to overcome the limitations of other far-red dyes. CF®633 is significantly brighter than spectrally similar dyes (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. CF®633 also is compatible with TIRF and other super-resolution imaging methods (learn more about CF® Dyes for Super-Resolution Imaging).

Figure 2. CF®633 yields the brightest far-red conjugates. Jurkat cells were stained with mouse anti-CD3 or isotype control antibody, followed by goat anti-mouse conjugates with varying degrees of labeling (DOL, or dye molecules per antibody). Fluorescence was measured in the APC channel of a BD FACSCalibur™ flow cytometer; bars represent geometric mean fluorescence.

CF®633 Technical Summary

  • Abs/Em maxima: 630/650 nm
  • Extinction coefficient: 100,000
  • Molecular weight: ~820
  • Laser line: 633 or 635 nm
  • Direct replacement for: Alexa Fluor® 633, Alexa Fluor® 647, Cy®5 and DyLight® 649

CF®633 Features

  • Brightest far-red fluorescent conjugates
  • Excellent photostability
  • Highly water soluble and pH-insensitive
  • Compatible with TIRF and other super-resolution methods

Figure 3. CF®633 and CF®640R are much more photostable than Alexa Fluor® 647. Jurkat cells were stained with mouse anti-CD3 antibody followed by goat anti-mouse secondary antibody conjugates of the indicated dyes. Cells were imaged with continuous mercury arc lamp excitation through a Cy®5 filter cube. Images were captured every 15 seconds for 5 minutes. Fluorescence was normalized to time 0.
Figure 4. Relative photostability of CF®633 and Alexa Fluor® 647 fluorescence. Jurkat cells were stained with mouse anti-CD3 antibody followed by goat anti-mouse secondary antibody conjugates of the indicated dyes. Cells were imaged with continuous mercury arc lamp excitation through a Cy®5 filter cube.

Figure 5. HeLa cells stained with CF®633 phalloidin (actin filaments, magenta) and DAPI (nuclei, cyan).
Figure 6. Rat neuromuscular junction stained with CF®633 α-bungarotoxin (magenta) and DAPI (cyan).
Figure 7. S. cerevisiae yeast stained with CF®633 concanavalin A (ConA) (cell walls, magenta).

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 GE Healthcare.

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Lectins, proteins, nucleotides, toxins, and other probes conjugated to our bright & photostable CF® dyes and other labels.

Primary Antibodies

Growing collection of more than 1000 monoclonal antibodies validated in IHC and other applications. Available with bright and photostable CF® dyes, R-PE, APC, PerCP, HRP, AP, biotin, or purified. Affordable 100 uL trial sizes.

CF® Dye Labeled & Biotinylated Secondary Antibodies

Many host/target species and cross-absorption options, featuring a wide spectrum of our bright & photostable CF® dyes or biotin.

Mix-n-Stain™ Antibody Labeling Kits

Mix-n-Stain™ kits use revolutionary technology that dramatically simplifies antibody labeling and requires no purification. The labeling is covalent and stable. Available with your choice of 24 CF® dyes, biotin, FITC, fluorescent proteins, enzymes, or haptens.

CF® Dye Protein Labeling Kits

Everything you need to label and purify antibodies or other proteins. Choose from 19 bright & photostable CF® dyes or biotin.

Reactive CF® Dyes

Our bright, photostable, highly water soluble CF® dyes with a wide selection of colors and functional groups.

Additional conjugates or reactive dye forms may be added on request, contact to inquire.

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CF® Dyes

See our CF® Dye Quick Reference Table for a list of dyes and summary of their features. Our CF® Dye Selection Guide has more detailed information on each CF® dye, and ordering information for our various CF® dye product lines. You can download CF® dye normalized absorption and emission data in Excel format.

Category: Mix-n-Stain™ Antibody Labeling Kits, CF® Dyes

← FAQs
CF® initially was an abbreviation for Cyanine-based Fluorescent dyes. These were the first patented CF® dyes based on cyanine dye structures. Since then, our CF® dye patent portfolio has expanded to include four different fluorescent dye core structures that cover the fluorescence spectrum from UV to NIR.

Category: CF® Dyes

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The exact chemical structures of CF® dyes are currently confidential but will be fully disclosed at a later stage when pending patents become granted. In general terms, the structure of a CF® dye may be divided into two parts: a) dye core structure (i.e. the aromatic ring skeleton that defines the dye’s color or absorption/emission wavelengths), and b) core structure-modifying elements. At present, CF® dyes bear the core structures of coumarin, pyrene, rhodamine or cyanine dyes. Blue fluorescent CF® dyes are based on coumarin or pyrene dye core structure, while green to near-IR CF® dyes are based on either cyanine or rhodamine dye core structures. Core structure-modifying elements refer to various chemical attachments to the core structure and are a key aspect of the CF® dye invention that makes CF® dyes superior to other commercial dyes.

Category: CF® Dyes

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