Microfluidics based assay device

• US 10,261,077 B2
• Filed: 05/16/2016
• Issued: 04/16/2019
• Est. Priority Date: 02/07/2011
• Status: Active Grant

• Current Assignee: Lumiradx UK Ltd
• Original Assignee: Lumiradx UK Ltd
• Inventors: Lowe, Phillip, Keatch, Steven Alexander, McGuigan, Brian
• Primary Examiner(s): Brown, Melanie
• Application Number:
  US15/155,594
• Publication Number:
  US 20160320374A1
• Time in Patent Office: 1,065 Days
• CPC Class Codes: B01L 2200/04 Exchange or ejection of cartridges, containers or reservoirs
• CPC Class Codes: B01L 2200/0647 Handling flowable solids, e.g. microscopic beads, cells, particles
• CPC Class Codes: B01L 2200/16 Reagents, handling or storing thereof
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/161 Control and use of surface tension forces, e.g. hydrophobic, hydrophilic
• CPC Class Codes: B01L 2400/043 magnetic forces
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: C12Y 101/03004 Glucose oxidase (1.1.3.4)
• CPC Class Codes: G01N 2333/904 acting on CHOH groups as donors, e.g. glucose oxidase, lactate dehydrogenase (1.1)
• 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 33/54326 Magnetic particles
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

A subtractive corrective assay device and methodology, whereby ail required binding and label detection reagents are initially located within the detection zone. Application of a magnetic field is used to selectively remove bound label from the detection zone by means of paramagnetic particles. The relationship between measured label concentration before and after the application of a magnetic field within the detection zone is used to accurately measure analyte concentration within the sample.

Claims

1. A method of determining the concentration of an analyte in a liquid sample, the method comprising:

(a) combining the sample with (i) an analyte binding agent that binds the analyte and (ii) a label for use in detecting the analyte, so that the analyte binding agent, the analyte, if present in the sample, and the label form an analyte binding agent/analyte/label complex;

(b) detecting a total level of the label present in a detection area, wherein the label is present in the analyte binding agent/analyte/label complex or is uncomplexed, to provide a first reference value;

(c) removing any binding agent/analyte/label complex from the detection area;

(d) detecting a level of any uncomplexed label and unreacted label that remains in the detection area after removal of the analyte binding agent/analyte/label complexes; and

(e) determining the concentation of the analyte present in the sample, if any, by subtracting the level of uncomplexed/unreacted label from the first reference value.

2. The method according to claim 1, wherein the detection is performed directly on the sample, without any separation, washing step, or dilution of the sample.

3. The method according to claim 1, wherein the detection is carried out electrochemically.

4. The method according to claim 3, wherein an oxidising or reduction potential is used to measure a level of label.

5. The method according to claim 4, wherein a potential is applied to reduce background effects caused by an electrochemical interferent that may be present in the sample.

6. The method according to claim 3, wherein the label is glucose oxidase.

7. The method according to claim 6, further comprising a peroxidase and a mediator that can be converted between oxidised and reduced forms that can be electrochemically detected.

8. The method of claim 7, wherein the peroxidase is horseradish peroxidase.

9. The method of claim 7, wherein the mediator is ferrocyanide or ABTS.

10. The method according to claim 1, wherein the binding agent is coupled to a particle capable of forming a complex with analyte present in the sample that can be removed, when complexed or uncomplexed with analyte from the detection area.

11. The method according to claim 10, wherein the particle is a paramagnetic particle that can be removed by a magnet or electromagnet.

12. The method according to claim 1, wherein the sample is a sample of whole blood.