Rapid assay strip and method of rapid competitive assay

• US 6,534,324 B1
• Filed: 05/12/2000
• Issued: 03/18/2003
• Est. Priority Date: 05/12/2000
• Status: Expired due to Fees

• Current Assignee: FCC Company Limited
• Original Assignee: Mizuho USA, Inc.
• Inventors: Zin, Benedict L.
• Primary Examiner(s): NGUYEN, BAO THUY L
• Application Number:
  US09/573,717
• Time in Patent Office: 1,040 Days
• Field of Search: 422/56, 422/57, 422/60, 422/61, 435/4, 435/7.1, 435/7.94, 435/287.1, 435/287.2, 435/287.3, 435/287.7, 435/287.9, 435/805, 435/810, 435/970, 436/514, 436/518, 436/810
• US Class Current: 436/518
• 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 436/81 Tube, bottle, or dipstick

Abstract

A competitive assay strip and method of rapid competitive assay incorporating an additional step, allowing optimization or at least substantial improvement of conditions for competition between analyte conjugates and analytes or alternatively, binding of analyte, which is tailored to each particular analyte.

Claims

1. A system for screening fluid samples for the presence of a compound of interest, comprising:

an elongated backing strip;

a sample pad, having a forward end and a rearward end, for receiving an aliquot of the liquid to be tested, said sample pad being composed of an absorbent material;

a conjugate pad, having a forward end and a rearward end, for receiving liquid flowing from said sample pad, said conjugate pad being composed of an absorbent material and disposed so that the forward end of said conjugate pad is in fluid communication with the rearward end of said sample pad when said conjugate pad and said sample pad are wet;

said conjugate pad having deposited thereon a conjugate solution of concentration C;

a bridge for receiving liquid flowing from said conjugate pad, said bridge having a forward end and a rearward end, and being composed of an absorbent material and disposed so that the forward end of said bridge is in fluid communication with the rearward end of said conjugate pad when said bridge and said conjugate pad are wet;

said bridge having deposited thereon, a buffer and having a length L and thickness T;

a display membrane having deposited thereon an immobilized protein, said display membrane having a forward end and a rearward end, and being composed of an absorbent material and being disposed such that the forward end of said membrane is in fluid communication with the rearward end of said bridge when said membrane and said bridge are wet; and

said concentration C, said buffer, said length L, and said thickness T being adapted to be independently adjustable parameters to optimize the system for detecting a particular compound of interest at a particular concentration.

2. The system according to claim 1, further comprising:

a rearward absorbent pad, adapted for receiving liquid, said rearward absorbent pad being composed of absorbent material and being disposed so that a forward end of said rearward absorbent pad is in fluid communication with said display membrane when said rearward absorbent pad and said display membrane are wet.

3. The system according to either one of claims 1 or 2 wherein said conjugate solution includes a conjugate including:

the compound of interest, a carrier protein, and indicia means; and

said immobilized protein includes antibodies specific to the compound of interest.

4. The system according to either one of claims 1 or 2 wherein:

said conjugate solution includes a conjugate including an antibody specific to the compound of interest and indicia means; and

said immobilized protein includes a conjugate including the compound of interest and means for immobilizing said compound of interest on said display membrane.

5. The system according to claim 4 wherein said means for immobilizing comprises conjugating the compound of interest with a protein carrier and adhering said protein carrier-compound of interest conjugate on said display membrane.

6. The system according to claim 4 where:

said buffer is approximately 50 mM tris(hydroxymethyl)aminomethane at a pH of approximately 8.5; and

said buffer includes approximately 0.1% polyoxyethylenesorbitan monolaurate.

7. The system according to claim 4 wherein:

said buffer is approximately 50 mM tris(hydroxymethyl)aminomethane at a pH of approximately 8.5; and

said buffer includes approximately 1.5% polyoxyethylenesorbitan monolaurate.

8. The system according to claim 4 wherein:

said buffer is approximately 50 mM Phosphate Buffered Saline at a pH of approximately 8.5; and

said buffer includes approximately 0.2% polyoxyethylenesorbitan monolaurate.