Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals
Reexamination Certificate
1998-01-09
2002-04-09
Chin, Christopher L. (Department: 1641)
Chemistry: analytical and immunological testing
Involving an insoluble carrier for immobilizing immunochemicals
C422S565000, C435S287100, C435S287200, C435S278000, C435S287900, C435S805000, C435S810000, C435S967000, C435S970000, C435S971000, C436S169000, C436S510000, C436S514000, C436S523000, C436S525000, C436S534000, C436S534000, C436S810000, C436S814000, C436S818000, C436S065000
Reexamination Certificate
active
06368876
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to immunological methods and devices for detecting analytes in biological samples.
Numerous approaches have been developed for detection of a given analyte in a biological sample. Typical of these methods are the so called “dipstick,” “lateral flow” and “flow-through” devices and methods. The dipstick generally uses a plastic strip with a reagent-containing matrix layered thereon. A test sample is applied to the device, and the presence of the analyte is indicated by a visually detectable signal such as a color-forming reaction. The flow-through device generally uses a porous material with a reagent-containing matrix layered thereon or incorporated therein. Test sample is applied to and flows through the porous material, and analyte in the sample reacts with the reagent(s) to produce a detectable signal on the porous material. These devices are generally encased in a plastic housing or casing with calibrations to aid in the detection of the particular analyte.
Lateral flow assays also utilize a porous membrane for performing analyte detection. Instead of drawing the sample through the membrane perpendicularly, however, the sample is permitted to flow laterally from an application zone to a reaction zone on the membrane surface. The capture reagent is present in the reaction zone, and the captured analyte can be detected by a variety of proto-cols, including direct visualization of visible moieties associated with the captured analyte.
For example, Hochstrasser, U.S. Pat. No. 4,059,407, discloses a dipstick device which can be immersed in a biological fluid to semi-quantitate analyte in the fluid. Semi-quantitation of the analyte is accomplished by using a series of reagent-containing pads wherein each pad in the series will produce a detectable color (i.e., a positive result) in the presence of an increasing amount of analyte.
Deutsch et al. describe a quantitative chromatographic test strip device in U.S. Pat. Nos. 4,094,647, 4,235,601 and 4,361,537. The device comprises a material capable of transporting a solution by capillary action, i.e., wicking. Different areas or zones in the strip contain the reagents needed to produce a detectable signal as the analyte is transported to or through such zones. The device is suited for both chemical assays and binding assays which are typified by the binding reaction between an antigen and its complementary antibody.
Many variations on the Deutsch et al. device have also been disclosed. For example, Tom et al., U.S. Pat. No. 4,366,241 discloses a bibulous strip with an immunosorbing zone to which the test sample is applied. Grubb et al., U.S. Pat. No. 4,168,146 describes the use of a porous test strip material to which is covalently bound an antigen-specific antibody. In performance of an assay, the test strip is immersed in a solution suspected of containing an antigen, and capillary migration of the solution up the test strip is allowed to occur. As the antigen moves up the test strip it binds to the immobilized antigen-specific antibody. The presence of antigen is then determined by wetting the strip with a second antigen-specific antibody to which a fluorescent or enzyme label is covalently bound. Quantitative testing can be achieved by measuring the length of the strip that contains bound antigen.
Numerous variations of the above test strip are disclosed in U.S. Pat. No. 4,435,504 which employs a two enzyme indicator system. U.S. Pat. No. 4,594,327 discloses the addition of a binding agent to whole blood samples which causes the red blood cells to aggregate at the area of the strip adjacent to the air/liquid interface. In addition, U.S. Pat. No. 4,757,004 discloses a means for controlling the shape of the fluid front migrating along the test strip. Also of interest are U.S. Pat. Nos. 4,298,688, 4,517,288 and 4,740,468 which describe sheet-like diagnostic devices comprising one or several strips, arranged behind one another, having zones situated one behind another. Each zone is readily accessible from above and below for the addition of reagents. Such devices can quantitatively determine the amount of an analyte.
In addition, European Publication No. 323,605 discloses an assay device using chromatographic material wherein the test sample can travel from one end to the other by capillary action. The chromatographic material contains an immobilized capture reagent capable of binding to the analyte. The application pad receives the test sample and contains a diffusive indicator reagent capable of migrating from the application pad to the chromatographic material. The indicator reagent is capable of binding to the analyte or the capture reagent. The binding of the indicator reagent results in a detectable signal.
Procedures using chromogenic and fluorescent dyes as labels in biological assay procedures are also known. Typical assay protocols call for direct or indirect binding of a dye label to an analyte or analyte analog in a biological sample, where the presence or absence of the dye at a particular stage of the assay can be determined visually and related to the amount of analyte initially present in the sample. A wide variety of specific assay protocols exist.
A number of those assays utilize naturally colored or dyed particles as a label, where the particles are bound to an antibody or other specific binding substance. Suggested particles include dyed latex beads, dye imbibed liposomes, erythrocytes, metal sols, and the like. The colored particle in such complexes can serve as a visible marker, where separation, capture, or aggregation of the particles is mediated through binding of the antibody or other specific binding substance. The amount of label thus segregated in a particular assay step is related to the amount of analyte initially present in the sample.
For example, U.S. Pat. No. 4,943,522 describes a solid phase lateral flow assay using erythrocytes as a label. U.S. Pat. No. 4,863,875 describes compositions comprising at least ten dye molecules or monomers covalently attached to an antibody through an isocyanate group on the dye. U.S. Pat. No. 4,703,017 describes a solid phase assay device which relies on specific binding of a ligand-label conjugate on a solid support, where the label is disclosed as a particle, such as a liposome, or polymer microcapsule. U.S. Pat. No. 4,608,246 describes assays for typing blood which employ erythrocytes as a labeling agent. U.S. Pat. No. 4,452,886 describes the covalent attachment of photon absorbing or emitting polymers to proteins, such as antibodies and antigens. U.S. Pat. No. 4,373,932 describes labeling of a ligand with an aqueous dispersion of a hydrophobic dye or pigment, or a polymer nuclei coated with such a dye or pigment. U.S. Pat. No. 4,313,734 describes methods of detecting sample analytes by the determination of the metallic label content in the sample. U.S. Pat. No. 4,169,138 describes immunoassays which employ visible particles including undyed microorganisms, bound to polymers which may be of microbial origin.
Other lateral flow protocols include U.S. Pat. No. 4,943,522 directed to a lateral flow device which relies on a nonbibulous support to conduct liquids from one portion of the device to another. PCT Publication WO 92/12428, which is related to the above patent, represents an improvement on that method and device wherein nonbibulous lateral flow is used to conduct visible moieties, especially labeled particles, e.g., dyed latex, red blood cells or liposomes capable of reacting with analyte or a competitor thereto into a capture zone for detection, using a bibulous support made nonbibulous by treatment with a blocking agent. The result is a one-step assay which can be conducted in a very short period of time (typically, within 60 seconds), and wherein the readout is usually available instantaneously upon the sample contacting a capture zone.
Other disclosures of lateral flow assays have also appeared. For example, U.S. Pat. No. 4,861,711 describes a lateral flow assay wherein all components needed for the detecti
Fan Eugene
Huang Ching
Brobeck Phleger & Harrison LLP
Chin Christopher L.
Genzyme Diagnostics
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