Nanoporous membrane immunosensor

• US 6,676,904 B1
• Filed: 07/12/2000
• Issued: 01/13/2004
• Est. Priority Date: 07/12/2000
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Lee, Gil U., Yanavich, Carolyn
• Primary Examiner(s): Le, Long V.
• Assistant Examiner(s): Counts, Gary W.
• Application Number:
  US09/614,727
• Time in Patent Office: 1,280 Days
• Field of Search: 422/57, 422/58, 422/68.1, 422/100, 422/101, 422/186.1, 436/526, 436/518, 436/165, 435/7.1, 435/6, 435/287.1, 210/600, 210/222, 210/321.75, 210/348, 210/455
• US Class Current: 422/535
• CPC Class Codes: G01N 33/537 with separation of immune complex from unbound antigen or antibody
• CPC Class Codes: G01N 33/54326 Magnetic particles
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: G01N 33/54393 Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding

Abstract

A sensor for a selected analyte in a test sample has (a) a semipermeable membrane with pores for retaining the analyte, where the membrane has been chemically modified by attachment of membrane modifiers; (b) immunoassay labels which have label binding ligands where these label binding ligands will have a binding affinity for the membrane modifiers in the presence of the analyte, and a measurably different binding affinity for the membrane modifiers in the absence of the analyte; and (c) a label detecting system, for detecting the presence of the labels on the membrane.

Claims

1. A sensor for a selected analyte in a test solution, comprising:

a test vessel;

a semipermeable membrane with pores for retaining the analyte, dividing said test vessel into a first volume and a second volume, said pores are selected to prevent the analyte from passing into or through said semipermeable membrane;

wherein said membrane is chemically modified by attachment of membrane modifiers on at least a side facing said first volume but not within said pores;

wherein said membrane supports a 100 kPa pressure load, said membrane is functionalized with a binder at the surface of said membrane in order for said membrane to act as a sensor;

assay labels, disposed within said first volume, said assay labels having label modifiers, said label modifiers having a binding affinity for the membrane modifiers in the presence of the analyte, and a measurably different binding affinity for said membrane modifiers in the absence of the analyte;

a pressure source, for driving said test solution from said first volume into said second volume; and

a label detecting system, for detecting the presence or absence of said labels on said membrane.

2. The sensor of claim 1, wherein said membrane has pores not greater than 25 nm in diameter.

3. The sensor of claim 1, wherein said membrane has pores not greater than 10 nm in diameter.

4. The sensor of claim 1, wherein said membrane has a pore density of at least 10¹²/m².

5. The sensor of claim 1, wherein said membrane has a pore density of at least 10¹⁵/m².

6. The sensor of claim 1, wherein said membrane is essentially flat and optically translucent.

7. The sensor of claim 1, wherein said membrane is an aluminum oxide membrane.

8. The sensor of claim 1,

wherein said membrane modifiers are selected from the group consisting of haptens, antibodies, nucleic acids, proteins, hormones, chelating agents, metal ions, and polymers; and

wherein said label modifiers are selected from the group consisting of haptens, antibodies, nucleic acids, proteins, hormones, chelating agents, metal ions, and polymers.

9. The sensor of claim 1, wherein said membrane has one or more regions with said attached membrane modifiers, and one or more additional regions that resist nonspecific adsorption.

10. The sensor of claim 1,

wherein said labels include magnetically active beads;

wherein said sensor further comprises an adjustable magnetic field source for producing an adjustable magnetic field for exerting a force on said beads; and

wherein said label detecting system comprises an imaging system, for observing individual beads bound to said membrane.

11. The sensor of claim 10, wherein said imaging system comprises an optical microscope, a digital image acquisition system, a digital image processing system, for identifying images of beads, and a counting system for counting images of beads.

12. The sensor of claim 10, wherein said beads have an average diameter between about 0.2 μ

m and about 200 μ

m.

13. The sensor of claim 10, wherein said adjustable magnetic field source is used to apply a field on said magnetically active beads that is essentially normal to said membrane.

15. A sensor as in claim 1, wherein an active surface of said membrane is coated with a biotin-polyethylene-glycol (PEG) using a polyethyleneimine (PEI) layer.

21. A sensor as in claim 1, wherein said membrane retains its flatness and rigidity even under pressure associated with flow of solution through said membrane.

14. A sensor for a selected analyte in test solution, comprising:

a test vessel;

a semipermeable membrane comprised of aluminum oxide with pores for retaining the analyte, dividing said vessel into a first volume and a second volume, said pores are selected to have a size to prevent the analyte from passing into or through said membrane;

wherein said membrane is chemically modified by attachment of membrane modifiers on at least a side facing said first volume but not within said pores;

wherein said membrane is functionalized with a binder at the surface of said membrane in order for said membrane to act as a sensor;

assay labels, disposed within said first volume, said assay labels having binding ligands, said binding ligands having a binding affinity for the membrane modifiers in the presence of the analyte, and a measurably different binding affinity for said membrane modifiers in the absence of the analyte;

a pressure source, for driving said test solution from said first volume into said second volume; and

a label detecting system, for detecting the presence or absence of said labels on said membrane.

16. A sensor as in claim 14, wherein an active surface of said membrane is coated with a biotin-polyethylene-glycol (PEG) using a polyethyleneimine (PEI) layer.

22. A sensor as in claim 14, wherein said membrane retains its flatness and rigidity even under pressure associated with flow of solution through said membrane.

17. A sensor for a selected analyte in test solution, comprising:

a test vessel;

a semipermeable membrane comprised of aluminum oxide with pores for retaining the analyte, dividing said vessel into a first volume and a second volume, said pores are selected to prevent the analyte from passing into or through said semipermeable membrane, wherein said membrane is chemically modified by attachment of membrane modifiers on at least a side facing said first volume but not within said pores and wherein said membrane is functionalized with a binder at the surface of said membrane in order for said membrane to act as a sensor and wherein said membrane remains translucent, and the shape of said membrane remains flat even under pressure associated with flow of solution through said membrane;

assay labels, disposed within said first volume, said assay labels having binding ligands, said binding ligands having a binding affinity for the membrane modifiers in the presence of the analyte, and a measurably different binding affinity for said membrane modifiers in the absence of the analyte;

a pressure source, for driving said test solution from said first volume into said second volume; and

a label detecting system, for detecting the presence or absence of said labels on said membrane.

18. A sensor as in claim 17, wherein an active surface of said membrane is coated with a biotin-polyethylene-glycol (PEG) using a polyethyleneimine (PEI) layer.

19. A sensor as in claim 17, wherein said pores allow a solvent to pass through while preventing flow of said binder, analyte, or assay labels.

20. A sensor as in claim 17, wherein said membrane is non-magnetic and is resistant to chemicals used by the assay.