LUMINESCENT POLYMER CYCLIC AMPLIFICATION

• US 20130071952A1
• Filed: 11/14/2012
• Published: 03/21/2013
• Est. Priority Date: 04/20/2011
• Status: Active Grant

• Current Assignee: Access Medical Systems, Ltd.
• Original Assignee: Access Medical Systems, Ltd.
• Inventors: ZUK, Robert F., TAN, Hong
• Granted Patent: US 8,647,889 B2
• Time in Patent Office: Days
• US Class Current: 436/501
• CPC Class Codes: G01N 2021/757 using immobilised reagents
• CPC Class Codes: G01N 21/76 Chemiluminescence; Bioluminescence
• CPC Class Codes: G01N 27/3277 being a redox reaction, e.g. detection by cyclic voltammetry voltammetry per se G01N27/42, G01N27/48
• CPC Class Codes: G01N 33/5306 Improving reaction conditions, e.g. reduction of non-specific binding, promotion of specific binding
• CPC Class Codes: G01N 33/533 with fluorescent label
• CPC Class Codes: G01N 33/5438 Electrodes
• 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
• CPC Class Codes: G01N 33/553 Metal or metal coated

Abstract

The present invention is directed to a luminescent immunoassay method for detecting an analyte in a liquid sample with high sensitivity. The invention provides a unique combination of (i) using a probe having a small sensing surface area for binding analyte molecules, (ii) using a high molecular weight branched polymer conjugated with multiple binding molecules and multiple luminescent labels, and (iii) cycling the probe having immunocomplex formed back to the reagent vessel and amplification vessel 1-10 times and repeating the reaction with the reagent and the amplification polymer, to improve the sensitivity of detection level. For each cycling, the luminescent signal is increased significantly over the noise.

Claims

1. A method of detecting an analyte in a liquid sample, comprising the steps of:

(a) obtaining a probe having a first antibody immobilized on the tip of the probe, wherein the diameter of the tip surface is ≦

5 mm;

(b) dipping the probe tip into a sample vessel containing a sample solution having an analyte to bind the analyte to the first antibody on the probe tip;

(c) dipping the probe tip into a reagent vessel containing a reagent solution comprising a reagent of a second antibody conjugated with a first member of a binding pair to bind the reagent to the analyte;

(d) dipping the probe tip into a first wash vessel containing a first wash solution to wash the probe tip;

(e) dipping the probe tip into an amplification vessel containing an amplification solution comprising a polymer conjugated with at least 5 molecules of second member of the binding pair and at least 25 luminescent labels, to form an immunocomplex of the analyte, the first antibody, the second antibody, and the first and the second members of the binding pair on the probe tip, wherein the polymer is branched, and has a molecular weight of at least 1 million daltons, and the luminescent labels has a molecular weight of less than 2,000 Daltons;

(flowing the amplification solution laterally in the amplification vessel)

(f) dipping the probe tip into a second wash vessel containing a second wash solution to wash the probe tip;

(g) repeating steps (c) to (f) 1-10 times, and

(h) detecting the immunocomplex formed by measuring the luminescent signal on the probe tip;

wherein the first antibody and the second antibody are antibodies against the analyte.

2. The method according to claim 1, wherein the tip surface is ≦

about 2 mm.

3. The method according to claim 1, wherein the binding pair is a hapten and its antibody, a ligand and its receptor, complementary strands of nucleic acids, or lectin and carbohydrates.

4. The method according to claim 3, wherein the binding pair is biotin and streptavidin, biotin and avidin, biotin and streptavidin, biotin and neutravidin, fluorescein and anti-fluorescein, digioxigenin/anti-digioxigenin, or DNP-anti-DNP,

5. The method according to claim 4, wherein the first member of the binding pair is biotin and the second member of the binding pair is streptavidin.

6. The method according to claim 1, wherein the polymer is a polysaccharide, a polynucleotide, a dendrimer, a polyols, or polyethylene glycol.

7. The method according to claim 1, wherein the polymer is crosslinked FICOLL®

.

8. The method according to claim 1, wherein the luminescent label is a fluorescent dye selected from the group consisting of:

cyanine, coumarin, xanthene and a derivative thereof.

9. The method according to claim 1, wherein the luminescent label is a chemiluminescent molecule selected from the group consisting of:

ruthenium(II)tris-bipyridine, luminol, acridinium ester, and hemin.

10. The method according to claim 1, wherein the polymer is conjugated with 5-50 binding molecules and 25-100 luminescent molecules.

11. The method according to claim 1, wherein the polymer is crosslinked FICOLL®

and is conjugated with 20-30 streptavidin and 40-90 Cy 5.

12. The method according to claim 1, wherein steps (c) to (f) are repeated 1-5 times.

13. The method according to claim 1, wherein steps (c) to (f) are repeated 2-3 times.