Fluorescent nanocrystal-labeled microspheres for fluorescence analyses

A method of using fluorescent microspheres for determining the presence or absence of a predetermined number of analytes in a sample, wherein a fluorescent microsphere comprises a plurality of fluorescent nanocrystals operably bound to a polymeric microsphere and further comprises affinity ligand operably bound thereto, the method comprising:

• (a) contacting the fluorescent microspheres with the sample under suitable conditions for the fluorescent microspheres to bind the predetermined number of analytes, if present in the sample, in forming complexes;
• (b) exposing the complexes, if formed, to an excitation wavelength light source suitable for exciting the fluorescent microspheres of the complexes to emit a fluorescence signal pattern;
• and
• (c) detecting the fluorescence signal pattern emitted by the complexes, if present, by a detection means for detecting the fluorescence signal pattern;
• wherein detection of the fluorescent signal pattern is indicative of the presence of an analyte of the predetermined number of analytes.