Methods and apparatuses for conducting assays

• US 20060019319A1
• Filed: 06/03/2005
• Published: 01/26/2006
• Est. Priority Date: 06/03/2004
• Status: Active Grant

• Current Assignee: Meso Scale Technologies, LLC
• Original Assignee: Meso Scale Diagnostics, LLC
• Inventors: Glezer, Eli N., Debad, Jeff D., Billadeau, Mark A., Leland, Jonathan K., Wijayawardhana, Charles A.
• Granted Patent: US 7,776,583 B2
• Time in Patent Office: Days
• US Class Current: 435/7.210
• CPC Class Codes: G01N 33/523 the element being adapted for a specific analyte
• CPC Class Codes: G01N 33/543 with an insoluble carrier for immobilising immunochemicals
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: Y10T 436/106664 Blood serum or blood plasma standard or control
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Abstract

Disclosed are methods for conducting assays of samples, such as whole blood, that may contain cells or other particulate matter. Also disclosed are systems, devices, equipment, kits and reagents for use in such methods. One advantage of certain disclosed methods and systems is the ability to rapidly measure the concentration of an analyte of interest in blood plasma from a whole blood sample without blood separation and hematocrit correction.

Claims

1. A method for measuring an analyte of interest comprising acts of:

(a) exposing a whole blood sample to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface; and

(c) measuring said amount of said analyte on said surface;

wherein said amount is dependent on the plasma concentration of said analyte and substantially independent of the hematocrit of said sample.

2. A method for measuring an analyte of interest comprising acts of:

(a) exposing a whole blood sample to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface;

(c) measuring said amount of said analyte on said surface; and

(d) determining, from said amount, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 20%;

wherein said determining act does not include a hematocrit correction.

5. The method of claim 2, wherein the portion of the whole blood sample that contacts the binding surface consists essentially of plasma.

6. The method of claim 2, wherein prior to the exposing act, the whole blood sample has not been subjected to a treatment effecting separation or partitioning of blood cells from the plasma fraction of the whole blood sample.

7. The method of claim 2, wherein in the determining act, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 10% is determined.

8. The method of claim 2, wherein in the determining act, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 5% is determined.

9. The method of claim 8, wherein in the determining act, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 2% is determined.

10. The method of claim 2, wherein in the determining act, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 1% is determined.

11. The method of claim 2, wherein said immobilizing act is performed over an interval of time during which less than 30% of said analyte in said sample is immobilized on said surface.

12. The method of claim 2, wherein said immobilizing act is performed over an interval of time which is less than 10 minutes.

13. The method of claim 2, further comprising calibrating said method using calibrator samples with known concentrations of said analyte.

14. The method of claim 13, wherein said calibrator samples are substantially free of red blood cells.

15. The method of claim 2, wherein said measuring is conducted in a sandwich assay format.

16. The method of claim 2, wherein said measuring is conducted in a competitive assay format.

17. The method of claim 2, wherein said binding surface has at least one binding reagent immobilized thereon.

18. The method of claim 17, wherein said binding reagent binds said analyte of interest.

19. The method of claims 17, further comprising contacting said sample with a bridging reagent that binds said binding reagent and said analyte.

20. The method of claim 2, further comprising binding said analyte of interest to a labeled binding reagent.

21. The method of claim 2, further comprising contacting said surface with a labeled analog of the analyte.

22. The method of claim 20, wherein a label of said labeled binding reagent is selected from a group comprising ECL label, luminescent label, fluorescent label, phosphorescent label, radioactive label or light scattering label.

23. The method of claim 21, wherein a label of said labeled analog is selected from a group comprising ECL label, luminescent label, fluorescent label, phosphorescent label, radioactive label or light scattering label.

24. The method of claim 2, wherein said surface is an electrode surface.

25. The method of claim 2, wherein said surface is within a flow cell.

26. The method of claim 2, wherein said surface is sufficiently rough so that a surface area accessible to said analyte is at least two-fold larger than the surface area accessible to red blood cells.

27. The method of claim 2, wherein said whole blood sample is flowed over said surface.

28. The method of claim 27, wherein said flow is laminar.

29. The method of claim 27, wherein said flow has a Reynold'"'"'s number of less than 100.

30. The method of claim 27, wherein said flow provides a plasma-rich layer adjacent to said surface.

31. The method of claim 27, wherein said sample is flowed over said surface in a back and forth motion.

32. The method of claim 2, further comprising displacing said whole blood sample from said surface prior to measuring said amount of said analyte on said surface.

34. The method of claim 32, wherein said whole blood sample is displaced from said surface by introducing a wash solution.

35. The method of claim 32, wherein after displacing said whole blood sample, the surface is further contacted with a solution containing a labeled binding reagent.

36. The method of claim 2, wherein said whole blood sample is undiluted.

37. The method of claim 2 further comprising adding anticoagulants to said whole blood sample prior to the exposing act.

39. The method of claim 2, wherein said act of exposing the sample to a binding surface comprises contacting at least a portion of the sample with a plurality of binding domains on one or more binding surfaces, said binding domains having different specificity for analytes of interest.

40. The method of claim 32, wherein one or more additional analytes are measured in said sample.

45. The method of claim 2, wherein said binding surface faces downward or sidewise during said immobilization act such that red blood cells in said sample settle away from said binding surface.

3. A method for measuring an analyte of interest comprising acts of:

(a) exposing a whole blood sample to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface; and

(c) generating an assay signal that is indicative of said amount of said analyte on said surface;

wherein said assay signal is dependent on the plasma concentration of said analyte and substantially independent of the hematocrit of said sample.

33. The method of claim 3, further comprising displacing said whole blood sample from said surface prior to generating said assay signal.

4. A method for measuring an analyte of interest comprising acts of:

(a) contacting a whole blood sample with a binding surface;

(b) immobilizing an amount of said analyte on said surface;

(c) generating an assay signal that is indicative of said amount of said analyte on said surface; and

(d) determining, from said signal, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 20%;

wherein said determining act does not include a hematocrit correction.

38. A method for performing rapid blood test comprising acts of:

a) drawing a sample of blood from a patient to provide a whole blood sample;

b) applying said whole blood sample to a cartridge, wherein said cartridge comprises a binding surface;

c) flowing said whole blood sample over said surface for a defined interval of time to immobilize an amount of said analyte on said surface;

d) measuring said amount of said analyte on said surface; and

e) determining, from said amount, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 20%;

wherein said determining act does not include a hematocrit correction.

41. A method for measuring an analyte of interest comprising acts of:

(a) exposing a sample containing particulate matter to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface; and

(c) measuring said amount of said analyte on said surface;

wherein said amount is dependent on the concentration of said analyte in the liquid fraction of said sample and substantially independent of the volume occupied by particulate matter in said sample.

42. A method for measuring an analyte of interest comprising acts of:

(a) exposing a sample containing particulate matter to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface;

(c) measuring said amount of said analyte on said surface; and

(d) determining, from said amount, a concentration value of said analyte in said sample that differs from the actual concentration of said analyte in a liquid fraction of said sample by no more than 20%;

wherein said determining act does not include correction for a volume occupied by particulate matter.

43. A method for measuring an analyte of interest comprising acts of:

(a) exposing a sample containing particulate matter to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface; and

(c) generating an assay signal that is indicative of said amount of said analyte on said surface;

wherein said assay signal is dependent on the concentration of said analyte in the liquid fraction of said sample and substantially independent of the volume occupied by particulate matter in said sample.

44. A method for measuring an analyte of interest comprising acts of:

(a) exposing a whole blood sample to a binding surface so that at least a portion of the sample contacts the binding surface;

(b) immobilizing an amount of said analyte on said surface;

(c) generating an assay signal that is indicative of said amount of said analyte on said surface; and

(d) determining, from said signal, a concentration value of said analyte in said sample that differs from the actual plasma concentration of said analyte in said sample by no more than 20%;

wherein said determining act does not include correction for a volume occupied by particulate matter.

46. A method for measuring an analyte of interest comprising an act of:

determining, in a particle-containing fluid sample comprising a fluid fraction and a plurality of particles suspended therein and containing the analyte, a measurement of the concentration of the analyte present in the fluid fraction that is substantially independent of the volume of the particles suspended in the fluid sample.

47. A method for measuring an analyte of interest comprising an act of:

determining, in a whole blood sample that has not been previously been subjected to a treatment effecting separation or partitioning of blood cells from plasma and that contains the analyte, a measurement of the concentration of the analyte present in the sample that differs from the actual plasma concentration of the analyte in the sample by no more than 20%, without correcting the measurement for the hematocrit of the whole blood sample.

48. The method of claim 47, wherein prior to the determining act, the whole blood sample has not been subjected to filtration, centrifugation, coagulation, substantial settling of cells induced by gravity, or affinity binding of the cells to any surface.

49. A method comprising acts of:

creating a flow of a whole blood sample over a surface, wherein said blood flow segregates blood cells contained in the sample away from the surface to create a plasma rich first region of the sample; and

determining a concentration value of an analyte of interest in the first region of the sample.

50. A method comprising acts of:

exposing a whole blood sample to a surface;

maintaining blood cells contained in the sample away from at least a portion of the surface to create a plasma rich first region of the sample; and

determining a concentration value of an analyte of interest in the first region of the sample.