Assay device and method

• US 7,736,890 B2
• Filed: 12/29/2004
• Issued: 06/15/2010
• Est. Priority Date: 12/31/2003
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Amir-Parviz, Babak, Whitesides, George M., Sia, Samuel K., Siegel, Adam, Linder, Vincent
• Primary Examiner(s): YU, MELANIE J
• Application Number:
  US10/584,819
• Publication Number:
  US 20070298433A1
• Time in Patent Office: 1,994 Days
• Field of Search: 422/50, 422/55, 422/58, 422/68.1, 422/82.05, 435/7.1, 435/283.1, 435/287.1, 435/287.2, 436/518, 436/524, 436/525, 436/43, 436/52, 436/53
• US Class Current: 435/287.2
• CPC Class Codes: B01L 2300/0822 Slides
• CPC Class Codes: B01L 2300/168 Specific optical properties, e.g. reflective coatings
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: G01N 2021/0346 Capillary cells; Microcells
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence
• CPC Class Codes: G01N 33/5302 Apparatus specially adapted for immunological test procedures
• CPC Class Codes: G01N 33/543 with an insoluble carrier for immobilising immunochemicals
• CPC Class Codes: G01N 33/56988 HIV or HTLV
• CPC Class Codes: G01N 33/585 with a particulate label, e.g. coloured latex
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/118339 with formation of a segmented stream

Abstract

An assay method is described, which comprises the steps of immobilizing a binding partner (e.g., an antigen or antibody) for an analyte to be detected (e.g., an antibody or antigen) on a portion (140) of a surface (130) of a microfluidic chamber (120,122,124); passing a fluid sample over the surface and allowing the analyte to bind to the binding partner; allowing a metal colloid, e.g., a gold-conjugated antibody, to associate with the bound analyte; flowing a metal solution, e.g., a silver solution, over the surface such as to form an opaque metallic layer; and detecting the presence of said metallic layer, e.g., by visual inspection or by measuring light transmission through the layer, conductivity or resistance of the layer, or metal concentration in the metal solution after flowing the metal solution over the surface.

Claims

1. A method of determining a sample component, comprising:

flowing a fluid sample over a surface of a microfluidic channel;

allowing a sample component to bind with a binding partner disposed on the surface of the microfluidic channel;

flowing in series in the microfluidic channel a predetermined sequence of fluid plugs including first, second and third fluids, wherein the first and second fluids are separated by the third fluid which is immiscible with both the first and second fluids;

accumulating an opaque material on a portion of the surface of the microfluidic channel; and

determining the sample component.

2. The method of claim 1 further comprising determining the opacity of the opaque material.

3. The method of claim 2 wherein determining comprises irradiating the opaque material with light and measuring light transmittance.

4. The method of claim 1 wherein the sample component is one of an antigen and an antibody and the binding partner is the other of the antigen and the antibody.

5. The method of claim 1 wherein the fluid is passed over a plurality of surfaces.

6. The method of claim 5 wherein each of the plurality of surfaces is associated with a different binding partner.

7. The method of claim 1 wherein the opaque material comprises a metal.

8. The method of claim 7 wherein the metal comprises silver.

9. The method of claim 7 wherein the opaque material is formed by electroless deposition.

10. The method of claim 9 wherein the opaque material is electrolessly deposited on a metal colloid.

11. The method of claim 10 wherein the metal colloid comprises gold.

12. The method of claim 10 wherein the metal colloid comprises a gold-conjugated antibody.

13. The method of claim 1 wherein the opaque material is deposited over a region having a dimension of at least 10 microns.

14. The method of claim 1 wherein the opaque material is formed by flowing a metal solution.

15. The method of claim 14 wherein the metal solution comprises a silver salt.

16. The method of claim 7 further comprising measuring the conductivity of the accumulated metal.

17. The method of claim 2 wherein determining comprises irradiating the opaque material with light and measuring light reflectance.

18. The method of claim 1 wherein the sample comprises whole blood.

19. The method of claim 1 wherein the micro fluidic channel comprises at least one cross-sectional dimension of less than 100 microns.

20. The method of claim 1 wherein the sample comprises urine.

21. The method of claim 1, wherein the binding partner is disposed across a width of the microfluidic channel.

22. The method of claim 1, wherein the opaque material forms a layer that extends across a width of the microfluidic channel.

23. The method of claim 1, wherein the opaque material has a horizontal dimension of greater than 100 microns.

24. The method of claim 3, wherein the light is pulse modulated.

25. The method of claim 1, wherein the opaque material has a thickness of greater than 10 nanometers.

26. The method of claim 1, wherein the binding and accumulating steps are performed while a fluid is flowing continuously in the microfluidic channel.

27. The method of claim 1, further comprising quantitatively determining the opacity of the opaque material.

28. The method of claim 1, wherein the first and second fluids are liquids and the third fluid is air.

29. The method of claim 1, wherein the first and/or second fluids is a rinse solution.

30. The method of claim 1, wherein the first fluid is a rinse solution and the second fluid is a metal solution.

31. The method of claim 1, comprising introducing the first, second and third fluids into the microfluidic channel from a vessel containing the fluids in the predetermined sequence.

32. The method of claim 31, wherein the vessel is sealed prior to use.

33. The method of claim 32, wherein the first, second and third fluids are stored for greater than 1 month in the vessel prior to use.

34. The method of claim 31, wherein the first, second and third fluids are introduced into the microfluidic channel by applying a vacuum.

35. The method of claim 1, comprising exposing the opaque material to light of a first wavelength and detecting transmission of light of the first wavelength.

36. The method of claim 1, comprising flowing in series over the binding partner disposed on the surface of the microfluidic channel the predetermined sequence of fluid plugs including the first, second and third fluids.

37. The method of claim 1, wherein the accumulation step is performed after the sample is flowed over a surface of the microfluidic channel.