System for electrochemical quantitative analysis of analytes within a solid phase and affinity chromatographic test strip

• US 6,485,983 B1
• Filed: 05/05/1999
• Issued: 11/26/2002
• Est. Priority Date: 05/05/1999
• Status: Expired due to Fees

• Current Assignee: InTec Science, Inc.
• Original Assignee: InTec Science, Inc.
• Inventors: Lu, Fang, Lu, Frank N. W., Wang, Kai Hua
• Primary Examiner(s): NGUYEN, BAO THUY L
• Application Number:
  US09/305,771
• Time in Patent Office: 1,301 Days
• Field of Search: 422/56, 422/57, 422/70, 422/82.01, 422/82.03, 422/98, 422/99, 422/110, 427/213.3, 427/213.34, 427/213.35, 436/516, 436/514, 436/518, 436/530, 436/541, 435/3, 435/7.1, 435/7.93, 435/287.7, 435/970, 204/182.7, 204/286, 204/288, 204/290
• US Class Current: 436/514
• CPC Class Codes: G01N 2458/30 Electrochemically active labels
• 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 435/97 Test strip or test slide

Abstract

System, method, and test strip for solid phase, electrochemical, quantitative analysis of analytes contained in biological fluid samples. Preliminary to analysis, a test sample solution can be applied to a sample collection pad associated with the solid phase test environment of the test strip. The test sample solution and a test kit reagent are thereby initially contacted, under assay conditions, within this solid phase test environment, and caused to migrate along a fluid pathway therein. Irrespective of the assay format (competitive assay, sandwich assay, etc.), a test kit reagent (e.g. labeled substance) and the analyte of interest (e.g. proteins, hormones or enzymes, small molecules, polysaccharides, antibodies, nucleic acids, drugs, toxins, viruses or virus particles, portions of a cell wall and other compounds which have specific or characteristic markers that permit their identification), either interact with one another to form a complex, or, alternatively, compete with one another for interaction with another test kit reagent, resulting in the concentration of an indicator substance within a delimited area of the solid phase. Thereafter, the delimited area of the test strip is subjected to electrochemical analysis and the results determined by monitoring an electrochemical transition in the form of an indicator, or derivative of the indicator (e.g. indicator species), by potentiostatic or potentiometric quantitative analysis (e.g. anodic stripping voltammetry). This electrochemical transition of the indicator has a characteristic electrical fingerprint that can be measured and which, when compared to a standard, can be correlated with the concentration of the analyte in the sample. This method is suitable for the determination/monitoring of therapeutic range of drugs (anti-convulsants drugs), determination of critical and potentially dangerous levels of endogenous materials which are indicative of disease states (prostate cancer), and numerous other applications presently requiring elaborate and time-consuming clinical laboratory analysis.

Claims

1. A system suitable for concurrent electrochemical, quantitative determination of multiple analytes, in a common test fluid sample, utilizing stripping voltammetry, said system consisting essentially of:

A. at least one test kit reagent comprising an electrochemically active labeled substance that is specific for binding interaction with an analyte of interest or mimicking of an analyte of interest within said analyte determination system;

B. a solid phase, porous, electrochromatographic medium having a common, linear fluid pathway defined therein, said linear pathway having a delimited area containing at least one immobilized binding material specific for binding to at least one labeled substance or to a complex of a labeled substance and an analyte suspected of being present in said common fluid test sample;

C. a sample absorbing means, in fluid communication with said electrochromatographic medium, for combining said test kit reagent(s) and a fluid test sample suspected of containing one or more analytes of interest;

D. electrode means coincident with and in spaced-apart relationship with said delimited area of said medium, said electrode means comprising an electrochemical cell including at least one working electrode and second electrode selected from the group consisting of a reference electrode and a counter electrode;

E. means for pre-concentration of an electrochemically active label from said electrochemically active labeled substance by electrolytic displacement of said electrochemically active label from said labeled substance(s), and/or from said complex(es) of a labeled substance and analyte(s), within said delimited area of said medium, so as to cause said electrochemically active label to form a deposit upon said working electrode of said electrochemical cell;

F. means for activation of said electrochemical cell so as to strip said label from said working electrode by stripping voltammetry and thereby produce a current signal response indicative of the concentration of said analyte(s) of said common test fluid; and

G. means for monitoring of said electrochemical cell for a current signal resulting from said stripping voltammetry, and thereby correlating said current signal with the presence of said analyte(s) of interest.

2. The system of claim 1, wherein the solid phase, porous electrochromatographic medium includes a second delimited area and a second means for establishing electrical contact therewith under assay conditions, and means for comparison or reference thereof to said electrochemical changes, characteristic of said label(s).

3. The system of claim 1, wherein the label is a metal selected from the group consisting of Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Mo, Tc, Pd, Cd, In, Sn, Sb, Ba, Hf, W, Re, Hg, Tl, Pb, La, Ce, Rh, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yd, Th, U, Pu and the isotopes thereof.

4. The system of claim 1, wherein the labeled substance comprises an analyte mimic, a complex of an analyte mimic a labeled ligand or a liposome containing a label.

5. The system of claim 1, wherein said concentration of said label is determined by potentiostatic measurement of said signal.

6. The system of claim 1, wherein said concentration of said label is determined by potentiometric measurement of said signal.

7. The system of claim 1, wherein the solid phase, porous electrochromatographic medium is further characterized as having a second delimited area and a second means for establishing electrical contact therewith, and means for comparison or reference thereof to said electrochemical changes, characteristic of said label(s).

8. The system of claim 1, wherein the label is a metal selected from the group consisting of Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Mo, Tc, Pd, Cd, In, Sn, Sb, Ba, Hf, W, Re, Hg, Tl, Pb, La, Ce, Rh, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yd, Th, U, Pu and the isotopes thereof.

9. The system of claim 1, wherein the label comprises a liposome containing a substance that is electroactive.

10. The system of claim 1, wherein said concentration of said label is determined by potentiostatic measurement of said signal.

11. The system of claim 1, wherein said concentration of said label is determined by potentiometric measurement of said signal.

12. A method for the concurrent electrochemical, quantitative determination of multiple analytes of a common fluid sample, in a solid phase, comprising:

A. Providing at least one test kit reagent comprising an electrochemically active labeled substance that is specific for binding interaction with an analyte of interest or mimicking of an analyte of interest within said analyte determination system;

B. Providing a test device which includes

(1) a solid phase, porous, electrochromatographic medium having a common, linear fluid pathway defined therein, said linear pathway having a delimited area containing at least one immobilized binding material specific for binding to at least one labeled substance or to a complex of a labeled substance and an analyte suspected of being present in said common fluid test sample;

(2) a sample absorbing means, in fluid communication with said electrochromatographic medium, for combining said test kit reagent(s) and a fluid test sample suspected of containing one or more analytes of interest;

(3) electrode means coincident with and in spaced-apart relationship with said delimited area of said medium, said electrode means comprising an electrochemical cell including at least one working electrode and second electrode selected from the group consisting of a reference electrode and a counter electrode;

C. Applying a fluid sample suspected of containing analytes of interest to said sample absorbent means, so as to combine said sample with and said labeled reagent(s),

whereby said fluid sample and said labeled reagent(s) are thereby combined and transferred to said solid phase, porous electrochromatographic medium, and thereupon flow along said medium, to said delimited area thereof and become bound within said delimited area; and

D. Pre-concentrating said labeled substance on a working electrode of said electrode means, by initially displacing said labeled substance(s) from said delimited area of said solid phase, porous electrochromatographic medium so as to cause said labeled substances to form a deposit upon said working electrode of said electrochemical cell;

E. Stripping said deposit from said working electrode by means of stripping voltammetry; and

F. Monitoring said test device for a current signal resulting from said stripping voltammetry, and thereby correlating said current signal with the presence of said analyte(s) in said common test fluid.