so both antibodies are binding to surface right now? is that the problem? I'm not sure what causes the problem. It might be that the secondary antibody which is attached to the beads binds unspecificly to the surface, as you suggest. It might as well be the other way around; the primary antibody on...

Hi, I have a problem with designing a sandwich immunoassay. The assay, against HSA, consists of two antibodies, one attached to a surface and one to small polystyrene beads. When the antigen HSA is present the beads should bind to the surface (and of course when the antigen isn't there the beads sho...