Patent ID: 8647889

Claim:
A method of detecting an analyte in a liquid sample, comprising the steps of: (a) obtaining a probe having a first antibody immobilized on the tip of the probe, wherein the diameter of the tip surface is ≦5 mm; (b) dipping the probe tip into a sample vessel containing a sample solution to bind an analyte in the sample solution to the first antibody on the probe tip; (c) dipping the probe tip into a reagent vessel containing a reagent solution comprising a reagent of a second antibody conjugated with a first member of a binding pair to bind the reagent to the analyte; (d) dipping the probe tip into a first wash vessel containing a first wash solution to wash the probe tip; (e) dipping the probe tip into an amplification vessel containing an amplification solution comprising a polymer conjugated with at least 5 molecules of second member of the binding pair and at least 25 luminescent labels, to form an immunocomplex comprising the analyte, the first antibody, the second antibody, the first and the second members of the binding pair, the polymer, and the luminescent labels on the probe tip, wherein the polymer is branched, and has a molecular weight of at least 1 million daltons, and each of the luminescent labels has a molecular weight of less than 2,000 Daltons; (f) dipping the probe tip into a second wash vessel containing a second wash solution to wash the probe tip; (g) repeating steps (c) to (f) 1-10 times, and (h) detecting the immunocomplex formed by measuring the luminescent signal on the probe tip; wherein the first antibody and the second antibody are antibodies against the analyte; wherein the first member of the binding pair is biotin, and the second member of the binding pair is streptavidin, avidin, or neutravidin.