Patent ID: 8309369

Claim:
A method of detecting an analyte in a liquid sample, comprising the steps of: obtaining a probe having a first antibody immobilized on the tip of the probe, wherein the diameter of the tip surface is ≦5 mm; dipping the probe tip into a sample vessel containing a liquid sample having an analyte; flowing the liquid sample laterally in the sample vessel to bind the analyte with the first antibody; dipping the probe tip into a reagent vessel containing a reagent solution comprising a branched and crosslinked polysaccharide having a molecular weight of at least 1 million Daltons and conjugated with at least 5 second antibody molecules and at least 25 fluorescent labels; flowing the reagent solution laterally in the reagent vessel to form an immunocomplex among the analyte, the first antibody, and the second antibody on the probe tip; dipping the probe tip into a washing vessel containing a wash solution; and detecting the analyte by measuring the fluorescent signal of the immunocomplex emitted only at the probe tip; wherein the first antibody and the second antibody are antibodies against the analyte.