Methods and arrays for target analyte detection and determination of target analyte concentration in solution
Arrays of single molecules and methods of producing an array of single molecules are described. Arrays with defined volumes between 10 attoliters and 50 picoliters enable single molecule detection and quantitation.
1. A method of detecting a target analyte in a sample, the method comprising:
a) providing a sample and a solid support, said sample comprising a biomolecule target analyte, said solid support comprising at least 1000 assay sites, each assay site having a defined volume between 10 attoliters and 50 picoliters;
b) contacting said solid support with said sample so that assay sites of the solid support contain biomolecule target analyte that is bound to capture components within the assay sites, and such that the ratio of a total number of biomolecule target analyte molecules contained within the assay sites to the total number of assay sites contacted with said sample is less than 1:5; and
c) determining the number of assay sites contacted with said sample which contain a biomolecule target analyte.
2. The method of claim 1 , wherein said ratio is 1:10.
3. The method of claim 1 , wherein said ratio is between 1:5 and 1:500.
4. The method of claim 1 , wherein said biomolecule target analyte is labeled.
5. The method of claim 1 , wherein said determining comprises detecting a change in an optical property at said assay sites as an indication of the presence of said biomolecule target analyte.
6. The method of claim 1 , further comprising determining the percentage of assay sites containing a biomolecule target analyte and determining a measure of the concentration of biomolecule target analyte in said sample from said percentage.
7. The method of claim 1 , further comprising, after step b), sealing the assay sites such that the contents of each assay site cannot escape said assay site.
8. The method of claim 1 , wherein said defined volume is measured in femtoliters.
9. The method of claim 8 , wherein said defined femtoliter volume is the same at each assay site and ranges from about 30 femtoliters to about 60 femtoliters.
10. The method of claim 9 , wherein said defined femtoliter volume is 46 femtoliters.
11. The method of claim 1 , wherein said solid support comprises between 20,000 and 30,000 assay sites.
12. The method of claim 1 , wherein said solid support comprises between 100,000 and 10,000,000 assay sites.
13. The method of claim 1 ,
wherein said biomolecule target analyte comprises a single-stranded nucleic acid, and said capture component comprises a complementary nucleic acid.
14. The method of claim 1 , wherein said biomolecule target analyte is selected from the group consisting of proteins, nucleic acids, lipids, and carbohydrates.
15. The method of claim 1 , wherein said biomolecule target analyte is selected from the group consisting of hormones, cytokines and cellular antigens.
16. The method of claim 1 , wherein said biomolecule target analyte is a receptor.
17. The method of claim 16 , wherein said receptor is selected from the group consisting of neural receptors, hormonal receptors, and nutrient receptors.
18. The method of claim 1 , wherein in step (c) a measure of the number of assay sites of said solid support contacted with said sample which contain a single biomolecule is determined.
19. The method of claim 18 , wherein a measure of the concentration of biomolecule target analyte in said sample is determined from the number of said assay sites which contain a single biomolecule.
20. The method of claim 1 , wherein the biomolecule target analyte is not an enzyme.
21. The method of claim 20 , further comprising the step of contacting the solid support with a plurality of secondary binding ligands, wherein a secondary binding ligand associates with the biomolecule target analyte.
22. The method of claim 21 , wherein the secondary binding ligand comprises an enzymatic component.
23. The method of claim 22 , further comprising contacting the solid support with a chromogenic enzymatic substrate, wherein the chromogenic enzymatic substrate is modified to a chromophore product upon exposure to a secondary binding ligand comprising an enzymatic component.
24. The method of claim 23 , further comprising determining a measure of the number of assay sites of said solid support which comprise a target analyte by determining the number of assay sites which contain a chromophore product.
25. The method of claim 1 , wherein said solid support comprises between 10,000 and 50,000 assay sites.
26. The method of claim 1 , wherein the sample comprises at least one cell comprising the biomolecule target analyte.
27. The method of claim 26 , further comprising lysing the cell prior to contacting said solid support with said sample.
28. The method of claim 1 , wherein step (b) comprises contacting said solid support with said sample, allowing at least some of said biomolecule target analyte molecules to become bound to capture components within the assay sites, and performing a wash step to remove biomolecule target analyte molecules that are not bound to the capture components from the solid support; and wherein it is after said washing step that the ratio of the total number of biomolecule target analyte molecules contained within the assay sites to the total number of assay sites contacted with said sample is less than 1:5.