Alexa Fluor® 647

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Alexa Fluor® 647 Technical Information

Alexa Fluor® 647-conjugated antibodies absorb light maximally around 651 nm and fluoresce maximally around 667 nm. They are brighter than Cy5 and DyLight 650 in aqueous mounting media. Alexa Fluor® 647- and APC-conjugated secondary antibodies are the best choice for flow cytometry when secondary antibodies fluorescing at these wavelengths are desired. Alexa Fluor® 647 conjugates are the best choice of far red-emitting dyes for multiple-labeling detection with a confocal microscope.

A significant advantage of using Alexa Fluor® 647 over lower wavelength-emitting dyes is the low autofluorescence of biological specimens in this region of the spectrum. However, because of its peak emission at 667 nm, Alexa Fluor® 647 cannot be seen well by eye, and it cannot be excited optimally with a mercury lamp. Therefore, Alexa Fluor® 647 is not recommended for use with conventional epifluorescent microscopes. It is most commonly visualized with a confocal microscope equipped with an appropriate laser for excitation and a far-red detector. Alexa Fluor® 647 conjugates are less expensive alternatives to allophycocyanin conjugates for flow cytometry.

Alexa Fluor® 647 has good color separation from DyLight 405, Alexa Fluor® 488, and Rhodamine Red-X for effective 4-color imaging.

Alexa Fluor® fluorescent dyes are a trademark of Life Technologies Corp.