Overview of Alexa Fluor Dyes
Alexa Fluor dyes, developed by American Molecular Probes, are popular fluorescent dyes for labeling and localizing tissues, cells, and biomolecules in biomedical research. Their excitation and emission spectra cover most of the visible spectrum and extend into the infrared range, making them compatible with many fluorescence microscopes.
The series is named after Alex Haugland, son of one of the company’s founders, Dick Haugland. Similarly, the Marina Blue dye honors Dick’s daughter, Marina. Each dye in the Alexa series is labeled according to the maximum wavelength (in nanometers) of its excitation light.
In 2003, Invitrogen acquired Molecular Probes and expanded the Alexa Fluor product line by introducing new dyes to fill gaps in the emission spectrum. After merging with Applied Biosystems in 2008, Invitrogen and the Alexa Fluor line became part of Life Technologies. Then, in 2014, Thermo Fisher Scientific acquired Life Technologies, reviving the Invitrogen brand and incorporating the Alexa Fluor products.
Product Comparison
Alexa Fluor dyes stand out for their sulfonate groups, which are introduced into coumarin, xanthene (like fluorescein and rhodamine), and cyanine dyes. This modification makes the dyes negatively charged and hydrophilic, boosting their optical stability, brightness, and pH adaptability.
Comparative studies have analyzed DNA staining capabilities between Alexa Fluor 647 and Cy5, which share similar wavelengths. Cy5 shines brighter but lacks the optical stability of Alexa Fluor 647. Furthermore, Alexa dyes generally show better photostability. For instance, Alexa Fluor 488 retains brightness more effectively than Dylight 488 and Fluoprobes 488.
| Alexa Fluor | APDye Fluor | Color† | Absorb (nm) |
Emit (nm) |
MW (g/mol) |
ε (cm−1M−1) |
Quantum Yield |
| Alexa Fluor 350 | APDye Fluor 350 | Blue | 346 | 442 | 410 | 19,000 | – |
| — 405 | APDye Fluor 405 | Blue | 401 | 421 | 1028 | 35,000 | – |
| — 430 | APDy Fluor 430 | Green | 434 | 541 | 702 | 15,000 | – |
| — Alexa Fluor 488 NHS ester | APDye Fluor 488 | Green | 495 | 519 | 643 | 73,000 | 0.92 |
| — 500 | Green | 502 | 525 | 700 | 71,000 | – | |
| — 514 | Green | 517 | 542 | 714 | 80,000 | – | |
| — Alexa 532 | APDye Fluor 532 | Yellow | 532 | 554 | 721 | 81,000 | 0.61 |
| — Alexa Fluor 546 | APDye Fluor 546 | Yellow | 556 | 573 | 1079 | 112,000 | 0.79 |
| — Alexa Fluor 555 | APDye Fluor 555 | Orange | 555 | 565 | ~1250 | 155,000 | 0.1 |
| — Alexa Fluor 568 | APDye Fluor 568 | Orange | 578 | 603 | 792 | 88,000 | 0.69 |
| — 594 | APDye Fluor 594 | Red | 590 | 617 | 820 | 92,000 | 0.66 |
| — 610 | Red | 612 | 628 | 1172 | 144,000 | – | |
| — Alexa Fluor 633 | APDye Fluor 633 | Far-red | 632 | 647 | ~1200 | 159,000 | – |
| — 635 | Far-red | 633 | 647 | – | 140,000 | – | |
| — Alexa Fluor 647 nhs ester | APDye Fluor 647 | Far-red | 650 | 665 | 1155.06 | 270,000 | 0.33 |
| — Alexa Fluor 660 | APDye Fluor 660 | Near-IR | 663 | 690 | ~1100 | 132,000 | 0.37 |
| — Alexa Fluor 680 | APDye Fluor 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 | APDye Fluor 800 | Near-IR | 782 | 805 | ~1750 | 260,000 | – |
| † = approximate colour of the emission spectrum ε = extinction coefficient |
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APDye Fluors: The Equivalent to Alexa Fluors
APDye Fluors are a series of fluorescent dyes developed by AxisPharm, designed to be equivalent to Alexa Fluors. These dyes offer vibrant colors and exceptional optical stability, ensuring consistent brightness during experiments. APDye Fluors are competitively priced and suitable for various applications, including the labeling and localization of tissues, cells, and biomolecules in biomedical research. Their excitation and emission spectra span most of the visible spectrum and part of the infrared range, making them compatible with most fluorescence microscopes.
Explore popular Fluorescent Dye products at AxisPharm now: