Invitrogen Alexa Fluor and Alexa Fluor Plus dyes are widely used and trusted fluorescent dyes. These dyes are spectrally diverse, high-performing, small molecule fluorophores that are compatible with a variety of fluorescence-based applications. In addition to excellent performance, you'll benefit from an experienced, problem-solving technical support team, over 80,000 published references, and a wealth of application and experimental tips and protocols to aid in experimental planning.

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Summary of Alexa Fluor and Alexa Fluor Plus dyes

With the wide range of Invitrogen Alexa Fluor and Alexa Fluor Plus dyes there is something for every filter and many options for multiplex detection. This series of fluorophores spans near-UV, visible and near-IR spectrum and are compatible with all common excitation sources and instruments.

ColorAlexa Fluor and Alexa Fluor Plus dyesExcitation/EmissionDye equivalents
BlueAlexa Fluor 350343/441AMCA, coumarin
Alexa Fluor 405401/422 
Alexa Fluor Plus 405404/455
GreenAlexa Fluor 430431/540
Alexa Fluor 488499/520Cy2, FITC (fluorescein)
Alexa Fluor Plus 488493/518
Alexa Fluor 514518/543 
YellowAlexa Fluor 532534/553
OrangeAlexa Fluor 546561/572
Alexa Fluor 555553/568Cy3, TRITC (rhodamine)
Alexa Fluor Plus 555558/572
Alexa Fluor 561556/569 
RedAlexa Fluor 568579/603Rhodamine red
Alexa Fluor 594590/618Texas Red
Alexa Fluor Plus 594590/618
Far RedAlexa Fluor 633631/650 
Alexa Fluor 635633/648
Alexa Fluor 647650/671Cy5
Alexa Fluor Plus 647658/675
Near-IRAlexa Fluor 660663/691 
Alexa Fluor 680681/704Cy5.5, IR680
Alexa Fluor Plus 680687/704
Alexa Fluor 700696/719 
Alexa Fluor 750752/776Cy7
Alexa Fluor 790782/805 
Alexa Fluor Plus 800789/794


Alexa Fluor and Alexa Fluor Plus products

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Conjugated primary antibodies

Alexa Fluor secondary antibodies

Antibody labeling kits

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Tyramide signal amplification

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Fluorescent streptavidin & avidin

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Protein labeling reagents

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Nucleic acid labeling

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Cell function assays

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Cell structure


Alexa Fluor and Alexa Fluor Plus resources


Advantages of Alexa Fluor dyes

Exceptional brightness

Protein conjugates made with Alexa Fluor dyes produce fluorescence output that surpasses that of other spectrally similar fluorophore-labeled proteins. Alexa Fluor dyes are available in a wide selection of fluorescent colors and are more photostable than most other dyes.

See brightness comparison data

Alexa Fluor dye molecules can be attached to proteins without significant self-quenching, leading to brighter conjugates available for imaging, flow cytometry, and other fluorescence-based applications.

Comparison of relative fluorescence of goat anti–mouse IgG antibody conjugates prepared from the Alexa Fluor 488 dye and fluorescein isothiocyanate (FITC). Conjugate fluorescence is measured by comparing the fluorescence quantum yield of the conjugated dye relative to that of a reference dye and multiplying by the dye:protein labeling ratio.
Comparison of relative fluorescence of goat anti–rabbit IgG antibody conjugates of the Alexa Fluor 555 and Cy3 dyes at different dye:protein ratios in the conjugate.
Flow cytometry comparison of the brightness of Alexa Fluor 647 goat anti–mouse IgG antibody (red, A21235) with Cy5 goat anti–mouse IgG antibody from Jackson ImmunoResearch Laboratories (green) and Amersham-Pharmacia Biotech (blue). Human blood was blocked with normal goat serum and incubated with an anti-CD3 mouse monoclonal antibody; cells were washed, resuspended and incubated with either an Alexa Fluor 647 or Cy5 goat anti–mouse IgG secondary antibody. Samples were analyzed on a flow cytometer equipped with a 633 nm He–Ne laser and a longpass emission filter (>650 nm).

Improved photostability

Photostability is a key characteristic of Alexa Fluor dye conjugates, allowing more time for image capture. In addition to their exceptional brightness and the wide selection of dyes across the spectrum, you'll get photostability you can rely on with Alexa Fluor dyes and dye conjugates.

See photostability comparison data

The photostability of Alexa Fluor dye molecules can be seen when compared to traditional fluorophores such as fluorescein.

Comparison of the photobleaching rates of the Alexa Fluor 488 and Alexa Fluor 546 dyes and the well-known fluorescein and Cy3 fluorophores. The cytoskeleton of bovine pulmonary artery endothelial cells (BPAEC) was labeled with (top series) Alexa Fluor 488 phalloidin and mouse monoclonal anti–a-tubulin antibody in combination with Alexa Fluor 546 goat anti–mouse IgG antibody or (bottom series) fluorescein phalloidin and the anti–a-tubulin antibody in combination with a commercially available Cy3 goat anti–mouse IgG antibody. The pseudocolored images were taken at 30-second intervals (0, 30, 90, and 210 seconds of exposure). The images were acquired with bandpass filter sets appropriate for fluorescein and rhodamine.

Reduced photobleaching, sustained signal. Bovine pulmonary artery endothelial cells were labeled with fluorescein phalloidin (A) or Alexa Fluor 488 phalloidin (B) which label filamentous actin. The cells were placed under constant illumination on the microscope. Images were acquired at one-second intervals for 30 seconds. Under these illumination conditions, fluorescein images are photobleached to about 20% of its initial value, while fluorescence of Alexa Fluor 488 phalloidin stayed at the initial value.


Additional advantages of Alexa Fluor Plus dyes

Detection of low-abundance targets with Alexa Fluor Plus dyes

While traditional Alexa Fluor dyes can be used in a variety of applications to detection proteins of varying expression levels, Alexa Fluor Plus dyes have been chemically optimized to provide higher signal to noise ratios and minimized cross-reactivity to help detect low-abundance targets in rare or precious samples.

See Alexa Fluor Plus data

Alexa Fluor Plus 405 conjugates allow for improved signal to noise when compared to traditional Alexa Fluor 405 conjugates. Traditional Alexa Fluor 405 secondary antibody (left) compared to Alexa Fluor Plus 405 secondary antibody (right, goat anti-rabbit IgG secondary antibody, Cat. No. A48254) in immunofluorescent analysis of β-III tubulin in fixed HeLa cells. Nuclei were stained with SYTOX Deep Red stain (Cat. No S11380). The images contain overlay of tubulin (cyan), and nuclei (magenta).  Images were taken on an EVOS M7000 Imaging system (Cat. No. AMF7000) at 20x magnification.

Alexa Fluor Plus 555 allows you to see greater detail compared to traditional Alexa Fluor 555 conjugates. Traditional Alexa Fluor 555 secondary antibody (left) compared to Alexa Fluor Plus 555 secondary antibody (right, goat anti-mouse IgG secondary antibody, Cat. No. A32727) in immunofluorescent analysis of β-III tubulin in E18 Sprague Dawley primary cortical neuronal cells. Nuclei were stained with Hoechst 33342 stain (Cat. No. H3570). The image contains overlay of neuronal tubulin (orange) and nuclei (blue). Images were taken on a confocal microscope at 40x magnification.

For Research Use Only. Not for use in diagnostic procedures.

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