Assay Device and Method

• US 20110053289A1
• Filed: 03/29/2007
• Published: 03/03/2011
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Original Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Inventors: Polwart, Ruth, Howell, Steven, Thomson, Alan Kenneth, Keatch, Steven Alexander, Marquordt, Claus, Lowe, Phillip
• Granted Patent: US 9,618,506 B2
• Time in Patent Office: Days
• US Class Current: 436/501
• CPC Class Codes: B01L 2200/0621 Control of the sequence of chambers filled or emptied
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0672 Integrated piercing tool
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0683 mechanically breaking a wall or membrane within a channel or chamber
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 2400/086 using baffles or other fixed flow obstructions
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence
• 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: B01L 3/502769 characterised by multiphase flow arrangements
• CPC Class Codes: B01L 9/527 for microfluidic devices, e.g. used for lab-on-a-chip
• 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 33/558 : using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387
• CPC Class Codes: G01N 35/0098 : involving analyte bound to insoluble magnetic carrier, e.g. using magnetic separation magnetic particles used in immunoassays G01N33/54326; magnetic separation in general B03C

Abstract

An assay method and device can perform at least one (e.g., at least two) assays on a single aliquot of a sample liquid. The device can mix a sample liquid with assay reagents including magnetically susceptible particles. The device is configured to create a sample liquid-air interface with the sample liquid. The magnetically susceptible particles can be located (via an applied magnetic field) at the liquid-air interface when a second liquid contacts the interface to form a liquid-liquid interface. The magnetic particles travel across the liquid-liquid interface to the second liquid. The magnetically susceptible particles are configured to trans-port an analyte across the interface into the second liquid. An assay for the analyte is performed in the second liquid. An assay for another analyte can also be performed in the sample liquid.

Claims

1-108. -108. (canceled)

109. A method comprising:

(a) introducing a liquid sample to a first portion of a channel of a microfluidic device;

(b) contacting, within the microfluidic device, magnetically susceptible particles with the liquid sample, the magnetically susceptible particles comprising a binding agent configured to bind a natriuretic peptide;

(c) forming, proximal to a junction between the first portion of the channel and a second portion of the channel, a liquid sample;

gas interface;

(d) forming a liquid sample;

second liquid interface by displacing gas of the liquid sample;

gas interface with a second liquid, and

(e) magnetically moving the magnetically susceptible particles across the liquid sample;

second liquid interface into the second liquid.

110. The method of claim 109 wherein the method is a method for a natriuretic peptide in the liquid sample, the magnetically susceptible particles adapted to bind the natriuretic peptide wherein the method further comprises the step of detecting natriuretic peptide in the second liquid.

114. The method of claim 109 wherein the first and second liquids are different, and wherein the first liquid is bodily fluid from a human or mammal chosen from:

blood, serum, or plasma.

127. The method of claim 109 wherein the step of contacting magnetically susceptible particles with the liquid sample comprises forming a mixture of the liquid sample and magnetic particles;

allowing magnetically susceptible particles to bind natriuretic peptide;

contacting the liquid sample with a binding agent configured to bind the natriuretic peptide, and forming complexes of magnetically susceptible particle, natriuretic peptide and binding agent, wherein the binding agent is conjugated to a detectable label and wherein the magnetically susceptible particles are conjugated to a first antibody configured to bind the natriuretic peptide, and wherein the binding agent is a second antibody configured to bind the natriuretic peptide at a different epitope to the first antibody.

146. The method of claim 109 wherein the step of magnetically moving the magnetically susceptible particles across the liquid sample:

second liquid interface into the second liquid comprises applying a magnetic field to a first position in the first channel portion, and moving the applied magnetic field along the channel through the junction to a second position in the second channel portion.

162. The method of claim 109 wherein in the step of forming a liquid sample:

second liquid interface by displacing gas of the liquid sample;

gas interface with a second liquid, the liquid sample;

second liquid interface is formed by directing the second liquid across the face of the liquid sample at the liquid sample;

gas interface, and wherein in the step of forming a liquid sample;

second liquid interface by displacing gas of the liquid sample;

gas interface with a second liquid, the liquid sample;

second liquid interface is formed by directing the flow of second liquid across the face of the liquid sample at the liquid sample;

gas interface to decrease an area of the liquid sample;

gas interface such that during flow of the second liquid across the face of the liquid sample the first liquid is held substantially static, and during which substantially no bulk movement of liquid occurs across the interface.

170. The method of claim 109 wherein the method comprises the step of magnetically positioning magnetically susceptible particles adjacent one or more electrodes configured in the second channel portion to contact the second liquid and wherein the step of detecting a characteristic comprises detecting an electrochemical signal in the second liquid, such that detection of natriuretic peptide in the second liquid comprises:

a. measuring at time T₁ the electrochemical signal Q₁ at the working electrode,

b. comparing Q₁ against a T₁ calibration dataset and, where Q₁ is within the T₁ dataset, using the T₁ dataset to determine an amount of natriuretic peptide in the buffer liquid,

c. where Q₁ does not exist in the T₁ calibration dataset, measuring at time T₂ the electrochemical signal Q₂ at the working electrode, wherein T₂>

T₁,

d. comparing Q₂ against a T₂ calibration dataset and where a valid comparison of Q₂ and T₂ is made, determining an amount of natriuretic peptide in the buffer liquid.

179. The method of claim 109, wherein the liquid sample:

gas interface has a cross sectional area of about 1 mm² or less, or wherein the liquid sample;

gas interface has a cross sectional area of about 0.15 mm² or more, and wherein the liquid sample;

gas interface has a first dimension H and a second dimension W and a ratio of W to H is at least 5, and wherein the liquid sample;

gas interface has a first dimension H and a second dimension W and a ratio of W to H is 30 or less and wherein the liquid sample;

second liquid interface has a cross sectional area of about the same as the liquid sample;

gas interface or less.

187. The method of claim 109, wherein, upon forming the liquid sample:

gas interface, the liquid occupies a total volume V of the channel upstream of the first liquid sample;

gas interface and the method comprises mixing the sample liquid by magnetically moving the particles within the volume V after forming the liquid sample;

gas interface and prior to forming the sample liquid;

second liquid interface, wherein V is chosen from one of;

about 2 μ

l, about 3 μ

l, about 5 μ

l, about 6 μ

l, about 7 μ

l, about 8 μ

l, about 9 μ

l, about 10 μ

l, about 15 μ

l, or about 20 μ

l.

206. The method of claim 109 wherein the method is for detecting an natriuretic peptide chosen from the group consisting of:

proBNP;

NTproBNP; and

BNP.

111-113. -113. (canceled)

115-117. -117. (canceled)

118. The method of claim 109 wherein the method further comprises the step of determining an assay result, comprising;

determining an amount of the natriuretic peptide;

comparing the amount of natriuretic peptide determined against a reference amount to produce an assay result, and displaying the determined amount of natriuretic peptide.

118-126. -126. (canceled)

128-145. -145. (canceled)

147-161. -161. (canceled)

163-169. -169. (canceled)

171-178. -178. (canceled)

180-186. -186. (canceled)

188-205. -205. (canceled)

207-290. -290. (canceled)

291. A microfluidic device comprising:

an inlet configured to receive a human blood or plasma sample, the inlet in fluid connection with a first portion of a channel containing a quantity of human blood or plasma;

reagents disposed in the first channel portion comprising magnetically susceptible particles conjugated to a first anti-natriuretic peptide antibody, and a second anti-natriuretic peptide antibody conjugated to an enzyme label, the human blood or plasma contained in the first channel portion comprising natriuretic peptide bound to the first and second anti-natriuretic peptide antibodies,

a second portion of the channel connected to the first portion at a junction;

wherein the device comprises a blood/plasma;

gas interface proximal the junction, the device further comprising;

a reservoir containing a quantity of second liquid and configured to deliver second liquid released from the reservoir into the second channel portion such that the second liquid flows towards the junction, the second liquid comprising a substrate of the enzyme label, and

at least one electrode configured on the second channel portion to detect an electrochemical signal from the second liquid.

292. The device of claim 291 wherein the channel has a capillary stop at, or adjacent, the junction and wherein at the junction the cross sectional area of the first channel portion is less than the cross sectional area of the second channel portion, and wherein the junction of the first and second channel parts is substantially orthogonal to the longitudinal axis of the first channel portion and the longitudinal axis of the second channel portion, and wherein the first and second channel parts have a common longitudinal axis.

293. The device of claim 291 wherein at the junction, the first channel portion has height h1 and the second channel portion has height h2, wherein h2>

h1 and the ratio h1;

h2 is at least 1;

2 and wherein at the junction the first channel portion has a cross-sectional area A1, and the second channel portion has a cross-sectional area A2, wherein A1<

A2 and the ratio of A1;

A2 is at least 1;

3 and wherein at the junction the first channel portion has a width w2, and the second channel portion has a width w5, wherein w5>

w2 and the ratio w2;

w5 is at least 1;

3 and wherein adjacent the junction of the first and second channel portions the base of the second channel portion is sloped between a region of the second channel portion distal of the junction and having height h3 and a region of the second channel portion adjacent the junction and having height h2, wherein h2>

h3.

294. The device of claim 291 wherein a wall of the second channel portion has a capillary stop, an upper edge of the slope extending across the second channel portion from a region at, or adjacent, the capillary stop towards the opposing wall of the second channel portion and wherein the upper edge of the slope extends obliquely across the channel and towards the junction.

295. The device of claim 291 wherein the second channel portion has a first region distal to the junction wherein the channel has a width w6 and height h3, the second channel portion having a tapered neck region formed between the first region and the junction in which the channel width and height increases to height h2 and width w5 at the junction, and wherein the first channel portion is rectangular in cross section and has height h1 and width w2, wherein h1 is at least about 0.06 mm and w2 is at least about 1.0 mm and wherein at the junction of the first and second channel parts the second channel portion is generally rectangular in cross section and has a height h2, and width w5, wherein h2 is at least about 0.35 mm and w5 is at least about 9 mm and wherein the second channel portion has a height h3 and a width w6 at distance d2 from the junction, wherein d2 is at least about 3.5 mm, and wherein the second channel portion has height h2 and width w5 at the junction of the first and second channel portions, wherein h2>

h3 and w5>

w6.