Electrochemical affinity biosensor system and methods

• US 20070054317A1
• Filed: 07/01/2004
• Published: 03/08/2007
• Est. Priority Date: 07/01/2003
• Status: Active Grant

• Current Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Deng, David, Ghoshal, Mitali, Diebold, Eric, Tsai, Jane
• Granted Patent: US 8,288,544 B2
• Time in Patent Office: Days
• US Class Current: 435/7.100
• CPC Class Codes: C07F 15/002 Osmium compounds
• CPC Class Codes: C07F 15/0026 without a metal-carbon linkage
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: G01N 2458/30 Electrochemically active labels
• CPC Class Codes: G01N 33/5306 Improving reaction conditions, e.g. reduction of non-specific binding, promotion of specific binding
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

The present invention provides novel osmium-based electrochemical species for the detection of wide variety of analytes using immunological techniques. The present invention also provides diagnostic kits and test sensors supporting electrode structures that can be used with the osmium-based electrochemical species. The test sensor can be fabricated to support interdigitated arrays of electrodes that have been designed to provide amplification of the electrical signal amplification desired to analyze analytes that may be present at low concentrations.

Claims

1. A compound of the formula II:

wherein R and R¹ are the same or different and each can be selected from;

2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, 5-5′

-disubstituted-2,2′

-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N, N′

-dimethyl 2,2′

-biimidazole, wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R¹ groups are coordinated to osmium through their nitrogen atoms;

R² is hydrogen, methyl, or ethyl;

-L- is a linker;

E is a trivalent linker;

B is a group comprising a ligand capable of binding to a specific analyte binding partner;

Z is chloro or bromo;

X is a counter ion; and

y is selected to provide a neutral salt; and

m is 2 to 4.

2. The compound of claim 1 wherein R and R¹ are the same and are selected from 2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, or 5-5′

-disubstituted-2,2′

-bipyridyl substituted with a methyl, an ethyl or a phenyl group.

3. The compound of claim 1 wherein L comprises —

(CH₂)_nQ-, Q is O, NR³ or S wherein R³ is H, CH₃ or C₂H₅, and n is an integer between 1 and 10.

4. The compound of claim 1 wherein L is —

(CH₂)_nN— and

n is an integer between 1 and 10.

5. The compound of claim 1 wherein E comprises a tridentate aromatic group.

6. The compound of claim 1 wherein E comprises a tridentate aliphatic group having one or more oxygen substituents.

7. The compound of claim 1 wherein B comprises an epitope recognizable by an antibody capable of specific binding to an analyte.

8. The compound of claim 1 wherein B comprises an epitope capable of binding to an analyte selected from the group consisting of:

a biowarfare agent, an abused substance, a therapeutic agent, an environmental pollutant, a protein or a hormone.

9. The compound of claim 1 wherein X is selected from the group of:

chloride, bromide, iodide, fluoride, tetrafluoroborate, perchlorate, nitrate, sulfate, carbonate, and sulfite.

10. A compound of the formula III:

wherein, R and R¹ are the same or different and each can be selected from;

2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, 5-5′

-disubstituted-2,2′

-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N, N′

-dimethyl 2,2′

-biimidazole, wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R¹ groups are coordinated to Os through their nitrogen atoms, R² is a saturated or unsaturated, substituted or unsubstituted, straight or branched chain, hydrocarbyl group having 1-10 carbon atoms;

—

R³ is H, CH₃ or C₂H₅;

L is (CH₂)_iQ wherein i is an integer between land 10, and Q is O, S, or NR³;

B is a group comprising a ligand capable of binding to a specific analyte binding partner;

X is a counter ion;

y is selected to provide a neutral salt; and

m is from 4-8.

11. The compound of claim 10 wherein R and R¹ are the same and are selected from 2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, or 5-5′

-disubstituted-2,2′

-bipyridyl substituted with a methyl, an ethyl or a phenyl group.

12. The compound of claim 10 wherein L is —

(CH₂)_nNR³ and n is an integer between 1 and 10.

13. The compound of claim 10 wherein the substituent R² is a saturated aliphatic group having between 1 and 10 carbons.

14. The compound of claim 10 wherein B comprises an epitope recognizable by an antibody capable of specific binding to an analyte.

15. The compound of claim 10 wherein B comprises an epitope capable of binding to an analyte selected from the group consisting of:

a biowarfare agent, an abused substance, a therapeutic agent, an environmental pollutant, a protein or a hormone.

16. The compound of claim 10 wherein L is —

(CH₂)_nS and n is an integer between 1 and 10.

17. The compound of claim 10 wherein X is selected from the group of:

chloride, bromide, iodide, fluoride, tetrafluoroborate, perchlorate, nitrate, sulfate, carbonate, and sulfite.

18. A compound of the formula:

wherein, R and R¹ are the same or different and each can be selected from;

2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, 5-5′

-disubstituted-2,2′

-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N,N′

-dimethyl 2,2′

-biimidazole wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R¹ groups are coordinated to Os through their nitrogen atoms;

R³ is H, CH₃ or C₂Hs;

L is (CH₂)_iQ, wherein i is an integer 1-10 and Q is O or NR³;

B is a group comprising a ligand capable of binding to a specific analyte binding partner;

Z is chlorine or bromine;

X is a counter ion;

y is selected to provide a neutral salt; and

m is 1 or 2.

19. The compound of claim 18 wherein R and R¹ are the same and are selected from 2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, or 5,5′

-disubstituted-2,2′

-bipyridyl substituted with a methyl, an ethyl or a phenyl group.

20. The compound of claim 18 wherein L is —

(CH₂)_nNR³ and n is an integer between 1 and 10.

22. The compound of claim 18 wherein Q is NR³.

23. The compound of claim 18 wherein B comprises an epitope recognizable by an antibody capable of specific binding to an analyte.

24. The compound of claim 18 wherein B comprises an epitope capable of binding to an analyte selected from the group consisting of:

a biowarfare agent, an abused substance, a therapeutic agent, an environmental pollutant, a protein or a hormone.

25. The compound of claim 18 wherein X is selected from the group consisting of:

chloride, bromide, iodide, fluoride.

26. A method of detecting an analyte in a liquid sample, said method comprising:

contacting a portion of said sample a specific binding partner for said analyte and a redox reversible conjugate, said conjugate comprising the compound of claim 18;

simultaneously applying a first potential voltage to a first working electrode and a second potential voltage to a second working electrode using a bipotentiostat; and

measuring a current generated by a portion of the redox reversible conjugate not bound to the specific binding partner.

27. A compound of the formula:

wherein, R and R¹ are the same or different and each can be selected from;

2,2′

-bipyridyl, 4,4′

-disubstituted-2,2′

-bipyridyl, 5,5′

-disubstituted-2,2′

-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N,N′

-dimethyl 2,2′

-biimidazole wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R¹ groups are coordinated to Os through their nitrogen atoms, R³ is H, CH₃ or C₂H₅;

L is (CH₂)_iQ, wherein i is an integer 1-10 and Q is O or NR³;

, A is —

(CH₂)_j—

NR³, —

(CH₂)_j—

SH, or an activated ester wherein j is an integer between 1-5;

Z is chlorine or bromine;

X is a counter ion;

y is selected to provide a neutral salt; and

m is 1 or 2.

28. The compound of claim 27 wherein A is —

(CH₂)_j—

NH₂ wherein j is an integer between 1-5.

29. A method of detecting an analyte in a liquid sample, said method comprising:

contacting a portion of said sample with a specific binding partner for said analyte and a redox reversible conjugate, said conjugate comprising an electrochemical label having two or four osmium atoms bound to a ligand capable of binding to the specific binding partner of the analyte;

simultaneously applying a first potential voltage to a first working electrode and a second potential voltage to a second working electrode using a bipotentiostat; and

measuring a current generated by a portion of the redox reversible conjugate not bound to the specific binding partner.

30. The method of claim 29 comprising correlating the either an oxidation current or a reduction current to the amount or concentration of the analyte in the sample.

32. The method of claim 29 comprising controlling a cathodic potential between a first working electrode and a reference electrode and controlling an anodic potential between a second working electrode and the reference electrode using a bipotentiostat.

33. A method of detecting an analyte in a liquid sample, said method comprising:

an immunoassay including contacting a portion of said sample with a specific binding partner for said analyte and a redox reversible conjugate, said conjugate comprising an electrochemical label having two or four osmium atoms bound to a ligand capable of binding to the specific binding partner of the analyte,

measuring steady state current generated by a portion of the redox reversible conjugates not bound to the specific binding partner within about 10 second after said contacting.

34. The method of claim 33 comprising a non-enzyme labeled assay.

35. The method of claim 33 wherein comprising a homogeneous immunoassay.

36. The method of claim 33 comprising measuring steady state current generated by a portion of the redox reversible conjugates not bound to the specific binding partner within about 5 seconds after said contacting.

37. A method of detecting an analyte in a liquid sample, said method comprising:

an immunoassay including contacting a portion of said sample with a specific binding partner for said analyte and a redox reversible conjugate, said conjugate comprising an electrochemical label having one, two, or four osmium atoms having a hydrophilic linker bound to a ligand capable of binding to the specific binding partner of the analyte, and

measuring steady state current generated by a portion of the redox reversible conjugates not bound to the specific binding partner within about 10 second after said contacting.

38. A test sensor comprising

a substrate supporting a sample port in fluid communication with a reaction chamber and a measurement zone;

a redox reversible conjugate effective for an immunoassay disposed in the reaction chamber or the measurement zone; and

an electrode structure including an interdigitated array of electrodes disposed in a single measurement zone, said interdigitated array of electrodes having at least a first working electrode, a second working electrode, a counter electrode and a reference electrode, said first working electrode and said second working electrode separated by a gap of between about 0.5 and about 25 μ

m, said electrode structure having a combined active electrode surface area of between about 20 and about 40 mm² and configured for use with a bipotentiostat, and wherein said sensor provides an assay result in less than about 10 seconds after introducing the sample into the sample port.

39. The test sensor of claim 38 wherein the measurement zone is configured to contain between about 2 and about 10 μ

l of liquid.

40. The test sensor of claim 38 wherein each of the first working electrode and the second working electrode have a width between about 0.5 and about 25 μ

m.

41. The test sensor of claim 38 wherein the measurement zone is defined by a chamber having internal wall portions and wherein the first working electrode and the second working electrode are positioned on the same wall portion.

42. The test sensor of claim 38 wherein the measurement zone is defined by a chamber having internal wall portions and said first working electrode is disposed on a first wall portion and the second working electrode is disposed on a dielectric material spaced from the first wall portion.

43. The test sensor of claim 38 providing a steady state current within less than about 5 seconds after introducing the sample into the sample port.

44. The test sensor of claim 43 providing a steady state current within less than about 2 seconds after introducing the sample into the sample port.

45. The test sensor of claim 38 wherein the electrode structure includes an interdigitated array of electrodes having between about 25 and about 750 fingers.

46. The test sensor of claim 38 wherein the interdigitated array of electrodes includes a vertical interdigitated array of electrodes.

47. A test sensor for analyzing a liquid sample containing an analyte of interest, said sensor comprising a substrate supporting a sample port in fluid communication with a reaction chamber and a measurement zone;

a redox reversible conjugate effective for an immunoassay and a binding ligand for the analyte of interest disposed in the reaction chamber or the measurement zone; and

an electrode structure including an interdigitated array of electrodes disposed in a single measurement zone, said interdigitated array of electrodes having at least a first working electrode, second working electrode, a reference electrode, and a counter electrode, and said electrode structure configured to have a cell constant less than about 0.03 cm<sup>−

1</sup>, and wherein said sensor provides an assay result in less than about 10 seconds after introducing the sample into the sample port.

48. The test sensor of claim 47 wherein the cell constant is less than about 0.02 cm⁻

1.

49. The test sensor of claim 48 wherein the cell constant is less than about 0.002cm⁻

1.

50. A kit for determining the concentration of one or more analytes in a test solution using an immunologic assay, said kit comprising:

a portable control unit;

a test sensor comprising;

a substrate including a reaction chamber and a measurement zone thereon;

a first working electrode and a second working counter electrode each disposed in the measurement zone, the first working electrode connected to a first contact and the second working electrode connected to a second contact, said substrate having a sample entry port in fluid communication with said reaction chamber;

a reagent composition disposed in said reaction chamber, said reagent composition including a binding agent selected to bind to a select one of the one or more analytes and a redox reversible conjugate provided to bind to said binding agent; and

a module operably coupled to said control unit and including a bipotentiostat connection to connect with the first and second contacts.

51. The kit of claim 50 wherein the portable control unit comprises a personal digital assistant.

52. The kit of claim 50 wherein the wherein the portable control unit comprises a laptop computer.

53. The kit of claim 50 wherein the test sensor comprises an interdigitated array of electrodes.

54. The kit of claim 50 wherein the first working electrode and the second working electrode both are supported on the same surface of the reaction chamber.

55. The kit of claim 50 wherein the first working electrode and the second working electrode are supported on different surfaces of the reaction chamber.

56. The kit of claim 50 wherein the interdigitated array of electrodes comprises between 25 to 1000 electrodes pairs.

57. The kit of claim 50 wherein the first working electrode is separated from the second working electrode by a gap of less than 20 microns.

58. The kit of claim 50 wherein the binding agent is selected to bind to a biowarfare agent, an abused substance, a therapeutic agent, an environmental pollutant, a protein, or a hormone.

59. The kit of claim 50 wherein the test sensor comprises a second reaction chamber including at least one electrode pair.

60. The kit of claim 50 wherein the test sensor comprises a plurality of reaction chambers, each reaction chamber includes at least one first working electrode and at least one second working electrode.

61. The kit of claim 50 wherein the test sensor is configured to detect an analyte at a concentration in the test sample of 0.1 μ

molar or less.

62. The kit of claim 50 comprising container defining a sample collection chamber and wherein the test sensor is mounted on the container and configured to allow contact a sample contained within the chamber.

63. The kit of claim 62 wherein the container is sealable to prevent removal of the sample contained therein.

65. The kit of claim 50 wherein portable module includes a bipotentiostat.

64. The kit of claim 64 wherein the container includes a removable lid and wherein the test sensor mounted on said lid.

66. A kit for determining the concentration of one or more analytes in a test solution using an immunologic assay, said kit comprising:

a portable control unit containing a bipotentiostat;

a test sensor comprising;

a substrate including a reaction chamber and a measurement zone thereon;

a first working electrode and a second working electrode each disposed in the measurement zone, the first working electrode connected to a first contact and the second working electrode connected to a second contact, said substrate having a sample entry port in fluid communication with said reaction chamber; and

a reagent composition disposed in said reaction chamber, said reagent composition including a binding agent selected to bind to a select one of the one or more analytes and a redox reversible conjugate provided to bind to said binding agent; and

a module operably coupled to said control unit and including a connection to connect with the first and second contacts.