Compositions and methods are disclosed for detecting multiple target
analytes in a sample using microparticles having molecular tags attached
by cleavable linkages. Generally, an assay mixture is formed comprising a
sample and a reagent comprising multiple such microparticles under
conditions that permit stable complexes to form between binding moieties
on the surfaces of the microparticles and the analytes. In one aspect of
the invention, the a second binding composition is added so that
complexes form among the microparticle-bound binding moieties, the
analytes, and second binding moieties of the second binding composition.
Such second binding moieties have cleavage-inducing moieties attached
that upon activation cause the cleavage of the cleavable linkages and the
release of molecular tags. Released molecular tags are separated and the
presence and/or amount of the target analytes are determined based on the
analysis of the released and separated molecular tags.