systems and methods for performing magnetic chromatography assays

• US 6,136,549 A
• Filed: 10/15/1999
• Issued: 10/24/2000
• Est. Priority Date: 10/15/1999
• Status: Expired due to Term

• Current Assignee: Wavesense, Inc.
• Original Assignee: Wavesense, LLC
• Inventors: Feistel, Christopher C.
• Primary Examiner(s): Chin, Christopher L.
• Assistant Examiner(s): PHAM, MINH QUAN K
• Application Number:
  US09/418,864
• Time in Patent Office: 375 Days
• Field of Search: 435/2, 435/5, 435/7.1, 435/7.21, 435/7.32, 435/239, 435/803, 435/287.2, 435/287.7, 435/287.9, 435/805, 435/810, 435/970, 436/513, 436/512, 436/518, 436/531, 436/526, 436/533, 436/538, 436/806, 436/824, 422/56
• US Class Current: 435/7.1
• CPC Class Codes: G01N 33/54333 Modification of conditions of immunological binding reaction, e.g. use of more than one type of particle, use of chemical agents to improve binding, choice of incubation time or application of magnetic field during binding reaction
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387
• CPC Class Codes: Y10S 435/803 Physical recovery methods, e.g. chromatography, grinding
• 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 436/806 Electrical property or magnetic property
• CPC Class Codes: Y10S 436/824 Immunological separation techniques

Abstract

Novel magnetic assay methods and systems, as well as systems for conducting spectrophotometric analysis therewith. According to a preferred embodiment, the magnetic assay methods and systems incorporate a chromatographic medium, such as an assay test strip, that is designed to be contacted with a test solution having activated magnetic particles. A magnetic field, generated by a magnet or electromagnet, is additionally provided that if selectively applied to a chromatographic medium which causes the charged particles to become substantially bound at a site all in the chromatographic medium specified by the position of the magnets, to thus form a captured line or zone. To the degree of magnetic force applied to the medium may be selectively adjusted to vary the width or surface area of the capture line or zone. Additionally, in a preferred embodiment, capture lines may be formed while test strips are in motion along a stationary magnetized rail. Spectrophotometric analysis may be made at the captured lines and zones for qualitative and quantitative analysis of unidentifiable analyte. A multimode photometer consisting of an optical canopy and base that defines an optical chamber may be utilized for conducting spectral or multi-spectral analysis.

Claims

1. A magnetic chromatography method for performing a bioassay comprising the steps:

a) providing a chromatographic medium;

b) providing a magnetic field;

c) providing a reaction mixture suspected of, containing an analyte, a reporter ligand that binds to said analyte, and a quantity of magnetic particles with capture ligands for binding said analyte immobilized thereon suspended therein;

d) contacting said chromatographic medium with said reaction mixture such that said reaction mixture flows laterally across said chromatographic medium;

e) applying said magnetic field at a site upon said chromatographic medium, said magnetic field being so applied such that a majority of said magnetic particles suspended within said reaction mixture is caused to become captured upon said medium at said site where said magnetic field is applied; and

f) analyzing said majority of magnetic particle captured upon said chromatographic medium.

2. The magnetic chromatography method of claim 1 wherein in step b), said magnetic field is generated by a magnet.

3. The magnetic chromatography method of claim 2 wherein in step b), said magnetic field is provided by a magnetic rail having a width between 0.003 inches and 3.0 inches, and having a length between 0.010 inches and 100 inches.

4. The magnetic chromatography method of claim 1 wherein in step b), said magnetic field is generated by an electromagnet.

5. The magnetic chromatography method of claim 1 wherein in step e), said magnetic field is applied by positioning a magnet in close proximity said chromatographic medium.

6. The magnetic chromatography method of claim 1 wherein in step c), said magnetic particles having an analyte, receptor, and label complexed therewith.

7. The magnetic chromatography method of claim 5 wherein said label comprises a detectable chemical moiety selected from the group consisting of radioactive, fluorescent, enzymatic, and dye moieties.

8. The magnetic chromatography method of claim 1 wherein in step b), said magnetic field is provided by at least two (2) magnets.

9. The magnetic chromatography method of claim 1 wherein in step c), said magnetic particles have a diameter ranging between 1 nm to 10 microns.

10. The magnetic chromatography method of claim 1 wherein in step a), said chromatographic medium comprises a test membrane.

11. The magnetic chromatography method of claim 1 wherein in step a), said chromatographic medium comprises a chromatographic plate.

12. The magnetic chromatography method of claim 1 wherein in step a), said chromatographic medium comprises a test, strip, said test strip comprising a backing having a liquid receiving end, test membrane and liquid absorbent end formed thereon in a sequential fashion, said test membrane being dispose intermediate to said liquid receiving end and said liquid absorbent end such that said liquid receiving end, test membrane and liquid absorbent end cooperates to define a lateral directions of flow.

13. The magnetic chromatography method of claim 1 wherein in step (c), said capture ligand is covalently bound to said magnetic particles.

14. The magnetic chromatography method of claim 1 wherein in step (c), said capture ligand is absorbed to the surface of said magnetic particles.

15. The magnetic chromatography method of claim 1 wherein step (c), said analyte is present in the sample and said analyte is selected from the group consisting of a control analyte and a calibrator analyte.

16. A magnetic chromatography method for sequentially performing a multiplicity of bioassays comprising the steps:

a) provide a multiplicity of chromatographic mediums;

b) providing a magnetic field;

c) providing at least one reaction mixture suspected of containing at least one analyte at least one reporter ligand that binds to said at least one analyte and a quantity of magnetic particles with capture ligands for binding to at least one of said analytes immobilized thereon suspended therein;

d) contacting said multiplicity of chromatographic mediums with said at least one reaction mixture such that said at least one reaction mixture flows laterally across each respective one of said mediums;

e) applying said magnetic field at dedicated sites upon respective ones of said multiplicity of chromatographic mediums, said magnetic field being so applied such that a majority of said magnetic particles suspended within said at least one reaction mixture is caused to become captured upon a respective one of said multiplicity of chromatographic mediums at said sites where said magnetic field is applied;

f) analyzing said majority of magnetic particles captured upon said chromatographic mediums.

17. The magnetic chromatography method of claim 16 wherein in step a), said chromatographic medium is selected from the group consisting of test membranes and chromatographic plates.

18. The magnetic chromatography method of claim 16 wherein in step b), said magnetic field is generated by a magnetic rail.

19. The magnetic chromatography method of claim 18 wherein in step b), said magnetic rail is situated in close proximity to dedicated sites upon respective ones of said multiplicity of chromatographic mediums.