"Alexa Fluor® 488 dye conjugate showed a 15–30% better signal-to-noise ratio than the DyLight™ 488 conjugate" - How true is this? Does anyone have any experience that says the opposite? Do Alexa Fluor dyes actually perform better than DyLight dyes?
Hello Theo. The quote is actually from the Invitrogen website (click the link). The molecules that I intend to label are the proteins on cells, from cell lines, for fluorescence microscopy.
http://www.b2b.invitrogen.com/site/us/en/home/brands/Molecular-Probes/Key-Molecular-Probes-Products/alexa-fluor/Alexa-Fluor-488-Versus-Other-Contenders.html
Hi Nurul, both dyes are variations of fluorescein.
Companies that sell these fluorescein derivatives with names like Oregon Green, Tokyo Green, SNAFL, carboxynaphthofluorescein, Alexa 488, FluoProbes 488 and DyLight 488 are all claiming that their fluor is superior in one way or another.
Personally, I cant tell the difference between Alexa and DyLight. Sorry.
As Steingrimur said, you would probably not see any difference in your experiments. The vendors' application notes and other material supporting their marketing claims don't necessarily conform to the highest scientific standards and can be expected to be strongly biased.
When it comes to more red-shifted fluorescent labels, stay away from Cy3/Cy5 and the alternative dyes from Alexa, Dyomics, Dylight, Oyster and the like. They all belong to the same fluorophore class, which is photochemical unstable, prone to ozone bleaching and have a low quantum yield.
Labels from Atto-Tec or Seta Biomedical will be a much better choice...
Well, this is an old thread, but I have to comment on one thing. Alexa dyes are superior to many others in multicolour confocal fluorescence because they have very narrow spectra. Although Atto dyes admittedly have very high fluorescence, they are typically poorly suitable for multicolour confocal imaging because their spectra are very wide. The high fluorescence part of the emission spectra typically spans about 50 nm more than for corresponding Alexa dye, i.e. 125 nm instead of 75 nm. With three colours you get approx. 375 nm of wavelength range in the high emission intensity part. If you have 420-800 nm or about 380 nm to use, that's it. You can circumvent it by using sequential imaging with different excitation lines on at different times, but when scanning a stack takes a minute, collecting one with sequential imaging in each slice takes about 8 minutes, switching between stacks still takes over two minutes. With Alexa dyes simultaneous three colour imaging is not even difficult. For single colour imaging Atto dyes for labelling proteins are much cheaper, though.
Dear Nurul,
opening this tread again, maybe this Harvard paper helps a bit
doi: 10.1038/nmeth.1768
Article Evaluation of Fluorophores for Optimal Performance in Locali...
They adressed phostability, amount of photons etc ... of serveal dyes. Unfortunatly they didn't compare Alexa Fluor 647 with DyLight 649 or as you mentioned Alexa Fluor 488 with DyLight 488 but it shows the variability of dyes comming from one company based on there structure. Which makes sense in my hand.
Nevertheless the comparision of Alexa Fluor 750 with DyLight 750 showed DyLight 750 beeing brighter (without regarding the lable efficacy to your proteins).
Best
André