With the wide range of Invitrogen Alexa Fluor dyes there is something for every filter and many options for multiplex detection. This series of superior fluorophores:

  • Spans the near-UV, visible and near-IR spectrum (Figure 1, Table 1).
  • Are compatible with all common excitation sources (Table 2) and instruments
  • Can replace standard fluorophores for most applications (Table 3)
  • Produce the brightest and most photostable conjugates, for multiplexing and multicolor detection

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Alexa Fluor dyes—Emission spectra

s001913-alexa-fluor-emission
Figure 1. Emission spectra for Alexa Fluor dyes.

Table 1. Properties of Alexa Fluor Dyes

Alexa Fluor dyeAbsorption
max. (nm)		Emission
max (nm)		Emission color*Extinction
coefficient**
Alexa Fluor 350346442Blue19,000
Alexa Fluor 405401421Blue34,000
Alexa Fluor 430433541Green/Yellow16,000
Alexa Fluor 488496519Green71,000
Alexa Fluor 532532553Yellow81,000
Alexa Fluor 546556573Orange104,000
Alexa Fluor 555555565Orange150,000
Alexa Fluor 568578603Orange/Red91,000
Alexa Fluor 594590617Red73,000
Alexa Fluor 610612628Red138,000
Alexa Fluor 633632647Far Red239,000
Alexa Fluor 635633647Far Red140,000
Alexa Fluor 647650665Near-IR***239,000
Alexa Fluor 660663690Near-IR***132,000
Alexa Fluor 680679702Near-IR***184,000
Alexa Fluor 700702723Near-IR***192,000
Alexa Fluor 750749775Near-IR***240,000
Alexa Fluor 790784814Near-IR***270,000
* Typical emission color seen through the eyepiece of a conventional fluorescence microscope with appropriate filters.
** Extinction coefficient at lmax in cm–1M–1. 
*** Human vision is insensitive to light beyond ~650 nm; it is not possible to view near-IR fluorescent dyes.

Table 2. Common fluorescence excitation sources

SourcePrincipal lines (nm)
Mercury arc lamp366, 405, 436, 546, 578*
Xenon arc lamp250-1000*
Tungsten–halogen lamp350-1000*
Blue diode laser405
Helium–cadmium laser325, 442
Argon ion laser457, 488, 514
Nd:YAG laser532**
Helium–neon laser543, 594, 633
Yellow diode laser561
Krypton ion laser568, 647
Red diode laser635
* Continuous white-light source.
** Frequency-doubled principal line output.

Table 3. Alexa Fluor Dye equivalents of common dyes

If you are usingTry this Alexa Fluor dye
AMCA, coumarinAlexa Fluor 350
Cy2, FITC (fluorescein)Alexa Fluor 488
Cy3, TRITC (rhodamine)Alexa Fluor 555
Rhodamine redAlexa Fluor 568
Texas RedAlexa Fluor 594
Cy5Alexa Fluor 647
Cy5.5, IR680Alexa Fluor 680
Cy7Alexa Fluor750

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