Patent ID: 7465540

Claim:
A method for detection of different reactive sites on at least one analyte, the method comprising: (1) providing a population of microspheres, wherein each of the microspheres carries different reactants capable of reacting respectively with the different reactive sites, wherein the at least one analyte comprises a nucleic acid molecule, wherein the different reactive sites comprise one or more alleles of a locus on the nucleic acid molecule, and wherein the different reactants comprise one or more fluorescently-labeled nucleic acid probes respectively specific for the one or more alleles; (2) allowing the different reactants and the different reactive sites to react, thereby forming reactant-reactive site pairs on the microspheres, wherein different reactant-reactive site pairs are detectably distinguishable from each other by their fluorescence intensity, and wherein the different reactant-reactive site pairs are not detectably distinguishable from each other by their fluorescence wavelength; and (3) detecting the fluorescence intensity of the reactant-reactive site pairs formed on one of the microspheres simultaneously, whereby the presence or absence of each of the different reactive sites on the at least one analyte is determined based on the fluorescence intensity of the reactant-reactive site pairs.