| abstract |
A method for performing a non-separation assay forndetermining the level of binding of one component tonanother. A first component is provided incorporating anfluorescent probe dissolved or suspended in solution. Ansubstantially opaque particle is provided onto or intonwhich is incorporated binding sites for the first componentnand optionally incorporating a dye or fluorophore ofndifferent emission spectrum to the first component. Thenopaque particle is immersed in a solution or suspension ofnthe first component, and the opaque particle to settle outnof the solution, or be transported to a fixed position bynan applied force. The solution and opaque particle arenillustrated with a beam of light such that the opaquenparticle is in the foreground and attenuates andnilluminating beam before it passes into the solutionnbeyond. The intensity of received light (fluorescence)nfrom the first component over an area of the sample with annimaging or scanning detector from the same side of thensample as the illuminating light is determined, and thenposition of the second component in the sample isndetermined by detecting attenuation of the received lightnfrom the sample and/or by detecting the presence ofnreceived light from a dye incorporated in the secondncomponent. An apparatus, as well as opaque particles fornperforming the method are also provided. |