Methods and apparatus for improved luminescence assays

Abstract

What is described are methods and apparatus for performing a binding assay for an analyte of interest present in a sample. The methods include the steps of: forming a composition containing the sample, an assay-performance-substance which contains a component linked to a label compound capable of chemiluminescing when triggered, and a plurality of particles capable of specifically binding with the analyte and/or the assay-performance-substance; incubating the composition to form a complex which includes a particle and the labeled component; collecting the complex in a collection zone; introducing into the collection zone a trigger capable of triggering the label such that the label luminesces; and measuring the emitted luminescence to measure the presence of the analyte of interest in the sample.

What is claimed is:  
     
         1 . A method for performing a binding assay for an analyte of interest present in a sample comprising the steps of: 
 (a) forming a composition containing 
 (i) said sample  
 (ii) an assay-performance-substance which contains a component linked to a label compound capable of chemiluminescing when triggered, and  
 (iii) a plurality of particles capable of specifically binding with the analyte and/or said assay-performance-substance;  
   (b) incubating said composition to form a complex which includes a particle and said labeled component;    (c) collecting said complex in a collection zone;    (d) introducing into said collection zone a trigger capable of triggering said label such that said label luminesces; and    (e) measuring the emitted luminescence to measure the presence of the analyte of interest in the sample.    
     
     
         2 . A method as recited in  claim 1  wherein said trigger is an oxidant capable of oxidizing said label.  
     
     
         3 . A method as recited in  claim 1  wherein said particles are magnetically responsive and said complex is magnetically collected in said collection zone.  
     
     
         4 . A method as recited in  claim 2  wherein said oxidant is hydrogen peroxide or superoxide.  
     
     
         5 . A method as recited in  claim 1  wherein said assay-performance-substance further contains an enzyme for converting a precursor to an oxidant capable of oxidizing said label, and said trigger is the precursor.  
     
     
         6 . A method as recited in  claim 5  wherein the enzyme is glucose oxidase, the precursor is glucose and the oxidant is hydrogen peroxide.  
     
     
         7 . A method as recited in  claim 1  wherein said particles further contain an enzyme for converting a precursor to an oxidant capable of oxidizing said label, and said trigger is the precursor.  
     
     
         8 . A method as recited in  claim 7  wherein the enzyme is glucose oxidase, the precursor is glucose and the oxidant is hydrogen peroxide.  
     
     
         9 . A method as recited in  claim 1  conducted as a batch process, the composition being permitted to reside within said cell for a time sufficient to permit collection of said particles.  
     
     
         10 . A method as recited in  claim 1  conducted as a flow process wherein said composition is flowed through said cell at a sufficiently low rate to permit collection of at least a portion of said particles.  
     
     
         11 . An assay method as recited in  claim 7  wherein said particles have a density of from 0.1 to 5 g/mL.  
     
     
         12 . An assay method as recited in  claim 11  wherein said particles have a density of from 0.5 to 2 g/mL.  
     
     
         13 . An assay method as recited in  claim 7  wherein the size of said particles, measured as the mean diameter, ranges from 0.001 to 100 μm.  
     
     
         14 . An assay method as recited in  claim 13  wherein the size of said particles ranges from 0.01 to 10 μm  
     
     
         15 . An assay method as recited in  claim 7  wherein the concentration of particles in said composition is from 1 to 10,000 μg/mL.  
     
     
         16 . An assay method as recited in  claim 15  wherein said concentration of particles is in the range of from 5 to 1000 μg/mL.  
     
     
         17 . An assay method as recited in  claim 7  wherein said particles have a magnetic susceptibility of at least 0.001 cgs units.  
     
     
         18 . A method as recited in  claim 17  wherein the magnetic susceptibility is at least 0.01 cgs units.  
     
     
         19 . An assay method as recited in  claim 7  wherein the magnetic susceptibility, density, size and concentration of said particles in said composition is such that the settling rate of said particles is at least 0.5 mm/mim.  
     
     
         20 . An apparatus for performing a binding assay for an analyte of interest present in a sample based upon measurement of chemiluminescence comprising: 
 (a) a cell defining a sample containing volume having a vertical columnar zone and having inlet and outlet means, and further including means for generating a magnetic field positioned below a substantial volume of said cell and said columnar zone; and    (b) means to measure the chemiluminescence generated at a collection zone.    
     
     
         21 . An apparatus as recited in claim  20  wherein said means for generating a magnetic field includes a plurality of magnets in north-south orientation and separated by nonmagnetic material.