FITC vs Alexa 488

William Telford TelfordW at mail.nih.gov
Mon Mar 25 01:30:57 EST 2002


Hello John...

We've made numerous Alexa Fluor 488 and other Alexa Fluor conjugates.  On
average they tend to be several times brighter than standard FITC
conjugates, although such comparisons are pretty qualitative at best.  The
biggest advantage in the Alexa Fluor dyes for us are their resistance to
photobleaching and their relative insensitivity to solution pH.  We have
substituted Alexa Fluor 488 for FITC wherever possible in applications such
as laser scanning cytometry, where photobleaching after multiple laser
scans is a serious concern.

And yes, no financial ties to Molecular Probes, etc., etc.!

Take care,

Bill Telford

At 08:58 AM 3/21/2002 -0800, John Krowka wrote:

>On Molecular Probes' website are claims that Alexa 488 is 6-7 times brighter
>than FITC. Preliminary evidence from our conjugations of the same antibody
>with FITC or Alexa 488 indicate no advantage from using Alexa 488. Can
>anyone who compared Alexa 488 and FITC share their findings?





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