Immunoassay devices and use thereof

• US 7,387,890 B2
• Filed: 12/16/2004
• Issued: 06/17/2008
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: Chembio Diagnostic Systems Incorporated (Chembio Diagnostics, Inc.)
• Original Assignee: Chembio Diagnostic Systems Incorporated (Chembio Diagnostics, Inc.)
• Inventors: Esfandiari, Javanbakhsh
• Primary Examiner(s): Chin; Christopher L.
• Application Number:
  US11/014,140
• Publication Number:
  US 20060134803A1
• Time in Patent Office: 1,279 Days
• Field of Search: 422/56, 422/57, 422/58, 435/5, 435/287.1, 435/287.2, 435/287.7, 435/288.4, 435/805, 435/810, 435/970, 436/514, 436/805, 436/810
• US Class Current: 435/287.2
• CPC Class Codes: G01N 33/54388 based on lateral flow
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387
• CPC Class Codes: Y10S 435/805 Test papers
• CPC Class Codes: Y10S 435/81 Packaged device or kit
• CPC Class Codes: Y10S 435/97 Test strip or test slide
• CPC Class Codes: Y10S 436/805 Optical property
• CPC Class Codes: Y10S 436/81 Tube, bottle, or dipstick
• CPC Class Codes: Y10S 436/815 Test for named compound or class of compounds
• CPC Class Codes: Y10S 436/816 Alkaloids, amphetamines, and barbiturates
• CPC Class Codes: Y10S 436/818 Human chorionic gonadotropin

Abstract

An immunoassay device has a housing defining a first opening for receiving a solution and a second opening through which a liquid sample is deposited, a strip of sorbent material having a test site with immobilized antigen or antibody for the ligand to be tested, and a filter for filtering the sample. The filter is located at the second opening and directly above the test site. The sorbent material defines a horizontal flow path in the housing for the solution from the first opening to the test site. In use, the sample is first applied via the filter to the test site, and then, after the ligand has been captured, a buffer added through the first opening is used to cause a secondary specific binder conjugated to a marker to migrate horizontally by capillary action to the test site where it can bind to the already captured ligand. This immunoassay offer several advantages over the traditional chromatographic immunoassays.

Claims

1. A test device for determining the presence of a ligand in a liquid sample, comprising:

a) a housing defining a first opening for receiving a solution and a second opening through which the liquid sample is deposited;

b) a strip of sorbent material, said strip including a test site having an immobilized ligand-binding mechanism, said strip disposed within said housing defining a horizontal flow path for the solution from adjacent said first opening to said test site, said test site being directly below said second opening;

c) a filter for filtering the sample, said filter located in or adjacently below the second opening and directly above said test site, wherein

said housing has a top wall with said second opening defined in said top wall, and said housing has a bottom wall with a window defined in said bottom wall, said window located adjacent said test site and permitting viewing of said test site.

2. A test device according to claim 1, wherein:

said strip supports a conjugate.

3. A test device according to claim 2, wherein:

said ligand-binding mechanism is an antigen or antibody for said ligand, and said conjugate comprises an antigen or antibody for the ligand and a marker coupled to the antigen or antibody.

4. A test device according to claim 3, wherein:

said marker is a colored marker viewable in the visible spectrum.

5. A test device according to claim 1, wherein:

said strip includes a control site spaced from said test site in a direction opposite to said first opening, and said housing defines a second window for viewing said control site.

6. A test device according to claim 5, wherein:

said second window is an extension of said window defined in said bottom wall.

7. A test device according to claim 1, wherein:

said filter extends through said second hole and is removable from said test device.

8. A test device according to claim 1, wherein:

said filter has a wide mouth and a narrow base.

9. A test device according to claim 8, wherein:

said test site is rectangular and said narrow base of said filter defines a rectangular cross section.

10. A test device according to claim 9, wherein:

said wide mouth of said filter is coated with plastic.

11. A test device according to claim 1, further comprising:

said solution which comprises a buffer.

12. A test device according to claim 1, further comprising:

said solution which comprises a subsystem of a buffer and a conjugate having an antigen or antibody for the ligand and a marker coupled to the antigen or antibody.

13. A test device according to claim 1, wherein:

said test site having an immobilized ligand-binding mechanism has an HIV antigen or antibody.

14. A test device according to claim 1, wherein:

said test site having an immobilized ligand-binding mechanism has one of antigens, antibodies, aptamers, nucleic acids, or enzymes for testing for pregnancy, tuberculosis, prion, or drugs.

15. A test device for determining the presence of a ligand in a liquid sample, comprising:

a) a housing defining a first opening for receiving a solution and a second opening through which the liquid sample is deposited;

b) a strip of sorbent material, said strip including a test site having an immobilized ligand-binding mechanism, said strip disposed within said housing defining a horizontal flow path for the solution from adjacent said first opening to said test site;

c) a filter for filtering the liquid sample extending through said second hole directly above said test site, and having a wide mouth and a narrow base which defines a rectangular cross-section, said filter being removable from said test device.

16. A test device according to claim 15, wherein:

said strip supports a conjugate, and

said ligand-binding mechanism is an antigen or antibody for said ligand, and said conjugate comprises an antigen or antibody for the ligand and a marker coupled to the antigen or antibody.

17. A test device according to claim 15, wherein:

said test site having an immobilized ligand-binding mechanism has an HIV antigen or antibody.

18. A test device according to claim 15, wherein:

said test site having an immobilized ligand-binding mechanism has one of antigens, antibodies, aptamers, nucleic acids, or enzymes for testing for pregnancy, tuberculosis, prion, or drugs.

19. A test device according to claim 15, wherein:

said housing has a top wall with said second opening defined in said top wall, and said housing has a bottom wall with a window defined in said bottom wall, said window located adjacent said test site and permitting viewing of said test site.