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Light scatter-based immunoassay

  • US 6,200,820 B1
  • Filed: 06/07/1995
  • Issued: 03/13/2001
  • Est. Priority Date: 12/22/1992
  • Status: Expired due to Fees
First Claim
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1. A particle light scatter-based immunoassay for measuring an analyte in a fluid sample, comprising steps:

  • (a) combining with said fluid sample a reagent set including first binding molecule-coated monodisperse microspheres and second binding molecule-coated colloidal particles smaller than said microspheres, or an immunoconiplex comprising said monodisperse microspheres and said colloidal particles, to form a mixture and allow a reaction to occur wherein at least one of said first and second binding molecules binds said analyte, said reaction being formation or decomplexation of said immunocomplex, so that the reacted mixture includes microspheres in uncompleted form, in said immunocomplex, or both, wherein the degree of binding of said microspheres to the colloidal particles in the reacted mixture, or the degree of decomplexation of the immunocomplex, is dependent upon presence or amount of said analyte in said fluid sample;

    (b) illuminating the reacted mixture with an incident light source to produce individual light scatter signals for each of said microspheres;

    (c) measuring said light scatter signals;

    (d) determining a degree of variation of a statistical distribution of the measured light scatter signals from said microspheres, such that the degree of variation of said statistical distribution varies with the degree of binding of said microspheres with said colloidal particles in said reacted mixture; and

    (e) correlating said degree of variation of said statistical distribution of said light scatter signals for said microspheres in said reacted mixture with the presence or amount of said analyte in said fluid sample.

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