Dual path immunoassay device
The systems of the invention include test cells with a first sorbent material defining a first flow path for a solution, a second sorbent material defining a second flow path distinct from the first flow path for a sample, and a test line or test site with immobilized antigens or antibodies or other ligand binding molecules such as aptamers, nucleic acids, etc. located at the junction of the first and second sorbent materials. The first and second sorbent strips touch each other at the test site location.
1. A test device for use with a solution and for use with a conjugate having a marker for determining the presence of a ligand in a liquid sample, the test device comprising:
a) a first sorbent strip having a first location for receiving a solution and defining a first migration path for the solution and the conjugate;
b) a second sorbent strip distinct from said first sorbent strip having a second location for receiving the liquid sample and defining a second migration path for the sample distinct from said first migration path; and
c) a test site located on or in said first sorbent strip and/or said second sorbent strip, said test site having an immobilized ligand-binding mechanism, and said first and second sorbent strips touching each other at the test site, and said second migration path extending laterally from said second location to at least said test site such that application of the liquid sample to the second location requires time for the liquid sample to laterally flow to the test site and does not immediately wet the test site upon application.
2. A test device according to claim 1 , further comprising:
d) a housing defining a first opening adjacent said first location, a second opening adjacent said second location, and a window adjacent said test site through which said test site is viewable.
3. A test device according to claim 1 , further comprising:
said conjugate wherein said first sorbent strip supports said conjugate.
4. A test device according to claim 3 , 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 said marker coupled to the antigen or antibody.
5. A test device according to claim 4 , wherein:
said marker is a colored marker viewable in the visible spectrum.
6. A test device according to claim 2 , wherein:
said strip includes a control site, and said housing defines a window for viewing said control site.
7. A test device according to claim 1 , wherein:
said first sorbent strip and said second sorbent strip are arranged in a “T” configuration.
8. A test device according to claim 1 , wherein:
said first sorbent strip and second sorbent strip are arranged in a “+” configuration.
9. A test device according to claim 1 , wherein:
said first sorbent strip has a first pore size and said second sorbent strip has a second pore size.
10. A test device according to claim 9 , wherein:
said second pore size is larger than said first pore size.
11. A test device according to claim 10 , wherein:
said first pore size is between 3 and 20 microns, and
said second pore size is between 20 and 40 microns.
12. A test device according to claim 2 , wherein:
one or both of said first and second sorbent strip includes a control site, and either said window is sized to permit viewing of said control site or a second window is provided in said housing to permit viewing of said control site.
13. A test device according to claim 1 , further comprising:
said solution, wherein said solution comprises a buffer.
14. A test device according to claim 1 , further comprising:
said solution, wherein said solution 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.
15. A test device according to claim 1 , wherein:
said immobilized ligand-binding mechanism comprises an HIV antigen or antibody.
16. A test device according to claim 1 , wherein:
said immobilized ligand-binding mechanism comprises antigens, antibodies, aptamers, nucleic acids, or enzymes for testing for at least one of pregnancy, HIV, tuberculosis (TB), prion, urine-analysis/drug, Chlamydia, cardiac markers, cancer markers, Chagas, dental bacteria (SM/LC), strep A, influenza A, influenza B, adenovirus/rotavirus, CPV, FIV, FeLV, and heartworm.
17. A test device according to claim 1 , wherein:
said first sorbent strip includes a first membrane and a first backing and said second sorbent strip includes a second membrane and a second backing, and said first sorbent strip and said second sorbent strip are arranged such that said first membrane is in contact with said second membrane.
18. A test device according to claim 17 , further comprising:
a first adhesive backing card underlying or overlying said first sorbent strip.
19. A test device according to claim 18 , further comprising:
a second adhesive backing card underlying or overlying said second sorbent strip.
20. A test device according to claim 1 , wherein:
said test device is for determining the presence of a plurality of different ligands in the liquid sample, and
said test site has a plurality of separate immobilized ligand-binding mechanisms for separately binding to respective of said plurality of different ligands.
21. A test device according to claim 20 , wherein:
said plurality of separate immobilized ligand-binding mechanisms includes a tuberculosis antigen and at least one HIV antigen.
22. A test device according to claim 20 , wherein:
said plurality of separate immobilized ligand-binding mechanisms includes p24 antibodies and at least one of an HIV1 and an HIV2 antigen.
23. A test device according to claim 20 , wherein:
said first sorbent strip supports a plurality of different conjugates comprising antigens and/or antibodies for the plurality of different ligands and markers coupled to the antigens and/or antibodies.
24. A method for testing a sample for the presence of a ligand, comprising:
a) obtaining a test device having a first sorbent strip having a first location for receiving a solution and defining a first migration path for the solution and for a conjugate having a marker, a second sorbent material having a second location for receiving the liquid sample and defining a second migration path for the sample distinct from said first migration path, and a test site located on or in said first sorbent strip and/or said second sorbent strip, said test site having an immobilized ligand-binding mechanism, and said first and second sorbent strips touching each other at the test site location and said second migration path extending laterally from said second location to at least said test site such that application of the liquid sample to the second location requires time for the liquid sample to laterally flow to the test site and does not immediately wet the test site upon application;
b) applying the sample to said second location;
c) after said applying the sample, applying the solution to the first location; and d) inspecting said test site to determine an indication of the presence or lack thereof of the ligand in the sample.
25. A method according to claim 24 , wherein:
said test device has a housing defining a first opening adjacent said first location, a second opening adjacent said second location, and a window adjacent said test site through which said test site is viewable,
said applying the sample comprises depositing the sample through said second opening to said second location,
said applying the solution comprises depositing the solution through said first opening to said first location, and
said inspecting comprises inspecting through said window.
26. A method according to claim 24 , wherein:
said test site has a visible soluble indicator; and
said method further comprises viewing the test site to observe the disappearance of the visible indicator prior to said applying said solution to said first location.