Electrochemical methods and devices for amending urine samples for immunosensor detection

• US 10,209,251 B2
• Filed: 10/06/2016
• Issued: 02/19/2019
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Abbott Point Of Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Point Of Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Di Tullio, Katrina, Collier, G. Bruce, Campbell, John Lewis Emerson
• Primary Examiner(s): Crawford, Erik B
• Application Number:
  US15/286,909
• Publication Number:
  US 20170023565A1
• Time in Patent Office: 866 Days
• Field of Search: None
• CPC Class Codes: C12Q 1/58 involving urea or urease
• CPC Class Codes: G01N 2333/47 Assays involving proteins of known structure or function as defined in the subgroups
• CPC Class Codes: G01N 2333/98 acting on amide bonds in linear amides (3.5.1)
• CPC Class Codes: G01N 2800/347 Renal failures; Glomerular diseases; Tubulointerstitial diseases, e.g. nephritic syndrome, glomerulonephritis; Renovascular diseases, e.g. renal artery occlusion, nephropathy
• 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 33/62 involving urea
• CPC Class Codes: G01N 33/6893 related to diseases not provided for elsewhere

Abstract

The present invention is directed to methods and devices for amending undiluted and partially diluted urine samples in a manner suitable for performing immunoassays for target analytes, for example NGAL. Generally, the urine sample is treated with reagents including at least one of buffer materials, water soluble proteins, urease, and other interferent mitigants. These reagents control the pH of the urine sample in a manner suitable for immuno-binding reactions and ameliorate interferences, particularly during the detection step.

Claims

1. A method for performing an immunoassay for a target analyte in a urine sample, the method comprising:

providing a test device with reagents disposed in a first region of the test device and at least one electrode disposed in a second region of the test device, wherein the reagents comprise urease and a buffer;

amending the urine sample with the reagents such that a dissolved urease enzymatic activity within the amended urine sample is in a range of about 10 to 10,000 IU/mL;

contacting the amended urine sample with the least one electrode coated with a biolayer comprising a capture antibody to bind to the target analyte, which is different from that of urea; and

determining a concentration of the target analyte within the amended urine sample using the at least one electrode.

2. The method of claim 1, wherein the urease reduces a urea concentration of the urine sample below a preselected urea threshold.

3. The method of claim 2, wherein the preselected urea threshold is 10 mM.

4. The method of claim 2, wherein the preselected urea threshold is 0.1 mM.

5. The method of claim 1, further comprising:

receiving the urine sample in a first conduit of the test device comprising the first region; and

moving the amended urine sample from the first region to the second region using a pump.

6. The method of claim 1, further comprising forming an immunocomplex on or substantially near the at least one electrode, wherein the immunocomplex comprises a labeled antibody bound to the target analyte and the target analyte bound to the capture antibody.

7. The method of claim 1, wherein:

the buffer adjusts a pH of the urine sample to within a preselected range; and

the buffer is selected from the group consisting of;

glycine, 3-(N-morpholino)propanesulfonic acid (MOPS), tris(hydroxymethyl)aminomethane (Tris), tricine, acetate, borate, 2-(N-morpholino)ethanesulfonic acid (MES), and 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES).

8. The method of claim 1, wherein the reagents are a dissolvable solid matrix comprising a sugar and printed on the first region.

9. The method of claim 1, wherein the urine sample is undiluted.

10. The method of claim 1, wherein the target analyte is neutrophil gelatinase-associated lipocalin (NGAL).

11. The method of claim 1, wherein the target analyte is selected from the group consisting of:

human chorionic gonadotrophin, troponin I, troponin T, Chlamydia, Legionella, acetaminophen, amphetamines, methamphetamines, barbiturates, benzodiazepines, cocaine, methadone, opiates, phencyclidine, marijuana, and tricyclic antidepressants.

12. The method of claim 1, wherein the reagents further comprise glutamine synthetase or any other urea cycle enzyme to consume ammonium.

13. The method of claim 1, wherein:

the reagents further comprise a sequestering enzyme to reduce and sequester excess phosphate below a preselected phosphate threshold; and

the sequestering enzyme is adenylate kinase.

14. A method for performing an immunoassay for a target analyte in a urine sample, the method comprising:

providing a test device with reagents disposed in a first region of the test device and at least one electrode disposed in a second region of the test device, wherein the reagents comprise urease and a buffer;

amending the urine sample with the reagents such that a dissolved urease enzymatic activity within the amended urine sample is in a range of about 10 to 10,000 IU/mL;

contacting the amended urine sample with the at least one electrode coated with a biolayer comprising a capture antibody to bind to the target analyte, which is different from that of urea;

washing the amended urine sample from the at least one electrode using a limited wash, wherein limited wash uses a volume of fresh wash buffer less than fifty times a volume of the amended urine sample and/or fewer than three independent cycles of the fresh wash buffer; and

determining a concentration of the target analyte within the amended urine sample using the at least one electrode.