Alexa Fluor
The Alexa Fluor family of fluorescent dyes is produced by Thermo Fisher Scientific sold under the Invitrogen brand name. Alexa Fluor dyes are frequently used as cell and tissue labels in fluorescence microscopy and cell biology.[1] Alexa Fluor dyes can be conjugated directly to primary antibodies or to secondary antibodies to amplify signal and sensitivity[2] or other biomolecules.
The excitation and emission spectra of the Alexa Fluor series cover the visible spectrum and extend into the infrared.[3] The individual members of the family are numbered according roughly to their excitation maxima (in nm).
Alexa Fluor dyes are synthesized through sulfonation of coumarin, rhodamine, xanthene (such as fluorescein), and cyanine dyes. Sulfonation makes Alexa Fluor dyes negatively charged and hydrophilic. Alexa Fluor dyes are generally more stable, brighter, and less pH-sensitive than common dyes (e.g. fluorescein, rhodamine) of comparable excitation and emission,[4] and to some extent the newer cyanine series.[5] They are patented by Invitrogen (which acquired the company that developed the Alexa Fluor dyes, Molecular Probes).
History
The Alexa Fluor dyes were named after Alex Haugland, son of Richard and Rosaria Haugland, the founders of Molecular Probes.
Dyes
| Colour† | Absorb (nm)[6] | Emit (nm)[6] | MM (g/mol) | ε (cm−1M−1)[6] | Quantum Yield [7] | |
|---|---|---|---|---|---|---|
| Alexa Fluor 350 | blue | 346 | 442 | 410 | 19,000 | - |
| — 405 | violet | 401 | 421 | 1028 | 35,000 | - |
| — 430 | green | 434 | 541 | 702 | 15,000 | - |
| — 488 | cyan-green | 495 | 519 | 643 | 73,000 | 0.92 |
| — 500 | green | 502 | 525 | 700 | 71,000 | - |
| — 514 | green | 517 | 542 | 714 | 80,000 | - |
| — 532 | green | 532 | 554 | 721 | 81,000 | 0.61 |
| — 546 | yellow | 556 | 573 | 1079 | 112,000 | 0.79 |
| — 555 | yellow-green | 555 | 565 | ~1250 | 155,000 | 0.1 |
| — 568 | orange | 578 | 603 | 792 | 88,000 | 0.69 |
| — 594 | orange-red | 590 | 617 | 820 | 92,000 | 0.66 |
| — 610 | red | 612 | 628 | 1172 | 144,000 | - |
| — 633 | Far-red | 632 | 647 | ~1200 | 159,000 | - |
| — 635 | Far-red | 633 | 647 | - | 140,000 | - |
| — 647 | Far-red | 650 | 665 | 1155.06[8] | 270,000 | 0.33 |
| — 660 | Near-IR | 663 | 690 | ~1100 | 132,000 | 0.37 |
| — 680 | Near-IR | 679 | 702 | ~1150 | 183,000 | 0.36 |
| — 700 | Near-IR | 702 | 723 | ~1400 | 205,000 | 0.25 |
| — 750 | Near-IR | 749 | 775 | ~1300 | 290,000 | 0.12 |
| — 790 | Near-IR | 782 | 805 | - | 260,000 | - |
| † = approximate color of the emission spectrum ε = extinction coefficient | ||||||
Comparison with other dyes
While extinction coefficients are known (see the table above), quantum yields and life times are not. Comparisons with other dyes should be considered depending on the conditions (technique) used and performance (signal, background, stability) needed.
The Alexa Fluor series dyes are less pH-sensitive and more photostable than the original dyes (fluorescein, rhodamine, etc.) from which they were synthesized. Brightness comparisons are also generally favorable. Comparisons with other dyes are less consistent, and also even more delicate, depending on the conditions (technique) used. A third party has compared Alexa Fluor 647 dye with Cy5 (similar wavelength), conjugated to DNA.[9]
Similar lines of fluorescent dyes provide an alternative to the Alexa Fluor Dyes (see also the list in Category:Fluorescent dyes).
References
- ↑ "Alexa Fluor Dyes Spanning the Visible and Infrared Spectrum". 2007-06-06. Archived from the original on 11 August 2007. Retrieved 2007-08-13.
- ↑ "Alexa Fluor Secondary Antibodies". www.thermofisher.com. Retrieved 2017-05-26.
- ↑ "The Alexa Fluor Dye Series". Molecular Probes, Inc. 2006-04-06. Archived from the original on 15 August 2007. Retrieved 2007-08-13.
- ↑ Panchuk-Voloshina N; Haugland RP; Bishop-Stewart J; et al. (1 September 1999). "Alexa dyes, a series of new fluorescent dyes that yield exceptionally bright, photostable conjugates". J. Histochem. Cytochem. 47 (9): 1179–88. PMID 10449539. doi:10.1177/002215549904700910. Archived from the original on 2 August 2007.
- ↑ Berlier JE; Rothe A; Buller G; et al. (1 December 2003). "Quantitative comparison of long-wavelength Alexa Fluor dyes to Cy dyes: fluorescence of the dyes and their bioconjugates". J. Histochem. Cytochem. 51 (12): 1699–712. PMID 14623938. doi:10.1177/002215540305101214.
- 1 2 3 http://www.lifetechnologies.com/sg/en/home/references/molecular-probes-the-handbook/technical-notes-and-product-highlights/the-alexa-fluor-dye-series.html
- ↑ "Fluorescence quantum yields (QY) and lifetimes (τ) for Alexa Fluor dyes—Table 1.5". Retrieved 2011-04-26.
- ↑ Supporting Information; Esteban, Fink, et al. Fungal recognition is mediated by the association of dectin-1 and galectin-3 in macrophages. Proceedings of the National Academy of Sciences of the United States of America. 2011. Vol 108, no 34, pg 14270-14275. 10.1073/pnas.1111415108
- ↑ Ballard JL; Peeva VK; deSilva CJ; Lynch JL; Swanson NR (July 2007). "Comparison of Alexa Fluor and CyDye for practical DNA microarray use". Retrieved 23 October 2010.