Biotin-streptavidin signal amplification - (Jun/02/2014 )
I'm using a biotinylated primary antibody, followed by PE-conjugated streptavidin. I've heard that using streptavidin and biotin can help to amplify signals, but I am right that this is only the case when the biotin is attached to the label? This seems to make sense as one streptavidin can bind four biotin molecules, but I've read conflicting information so I'm not too sure...
The available formats for biotin-streptavidin interactions are generally unidirectional. Biotinylated primaries, with avidinylated conjugates.
At the scales of sensitivity we're talking about, particularly with the most recent generation of digital cytometers, the kind of multivalent amplification you're talking about is more likely to lead to artifactual noise signal than real amplification.
Instead, try titering up the primary you're using, or shopping around for higher affinity mAb clones, if you're really concerned with sensitivity.