Chemistry: analytical and immunological testing – Involving diffusion or migration of antigen or antibody
Reexamination Certificate
1996-09-25
2001-02-27
Housel, James (Department: 1648)
Chemistry: analytical and immunological testing
Involving diffusion or migration of antigen or antibody
C436S535000, C436S518000, C435S004000, C435S007100
Reexamination Certificate
active
06194220
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to processes for assaying for an analyte in a sample and to products for utilizing such processes. More particularly, the invention relates to novel solid phase assays.
BACKGROUND OF THE INVENTION
Immunoassay methods, in general, are based on the competition between a specific analyte, the amount of which is to be determined in a sample and a known amount of tracer, which is generally the analyte or appropriate analog thereof in labeled form, with the analyte and tracer competing for a limited number of available binding sites on a binder which is specific for the analyte and tracer.
If the concentration of tracer and binder is fixed and the only variable is the level of analyte, it is possible to establish an assay system for measuring the unknown level of analyte by determining the amount of bound and/or free tracer in the system. The values determined in the assay are compared with the values given by a range of known amounts of the analyte treated in the same manner, and by such comparison, it is possible to determine the amount of analyte in the sample.
In one such procedure, the binder is supported on a solid support, whereby the bound and free components of the assay, after incubation, may be easily separated by separation of the sample and the solid support.
In many cases, the tracers used in such assays require either instrumentation and/or treatment of the tracer in order to determine the tracer in the bound and/or free portion of the assay as a measure of analyte. Thus, for example, in an assay in which an enzyme is used as the label or marker for the tracer, the enzyme must be developed with a suitable developer. When a label or marker is a fluorescent material, the tracer in the bound and/or free portion is determined by the use of appropriate instrumentation for determining fluorescence.
An early test strip device is described by Deutsch, et al., in U.S. Pat. No. 4,361,537. In general, the device comprises a material capable of transporting a solution by capillary action, i.e., a wicking or chromatographic action. Different areas or zones in the test strip contain the assay reagents needed to produce a detectable signal as the analyte is transported to or through such zones. The device is suitable for chemical assays and binding assays and uses a developer solution to transport analyte along the strip.
Many alternatives to or variations on the Deutsch, et al. device have been disclosed. For example, 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 performing the assay, the test strip is immersed in a solution suspected of containing an antigen, and capillary migration of the solution through the test strip is allowed to occur. As the antigen moves through the test strip it binds to the immobilized antigen-specific antibody. The presence of antigen is then determined by wetting the test 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 and labeled antigen.
Tom, et al. (U.S. Pat. No. 4,366,241) describe a device comprised of a test zone (immunosorbing zone) and a liquid absorbing zone in liquid receiving relationship with the test zone. The immunosorbing or test zone has a member of an immunological pair (a “MIP”) affixed to a solid support, where the MIP is inhibited from diffusing from the zone. In use, the analyte in the sample solution passes through the immunosorbing zone and binds to the MIP and is concentrated in the immunosorbing zone. The device includes a signal producing system for production of a detectable signal in the test zone in relation to the amount of analyte present in a sample. Tom, et al. teaches the use of the signal producing signal that provides for a detectable signal in the immunosorbing zone which can be compared to a signal level based on a standard having an unknown amount of analyte.
Weng, et al. (U.S. Pat. No. 4,740,468) describe another device and method for performing a specific binding assay. The assay involves both an immobile second binding member which binds to a mobile first binding member and an immobilized analog of the analyte which removes the unbound first binding member from the assay system prior to it being contacted to the detection site.
Greenquist, et al. (U.S. Pat. No. 4,806,311) describe a similar device wherein a first immobilized reagent, such as an analyte-analog is present in a reagent zone to remove free monovalent labeled-binding members from the assay system prior to the test samples contacting the detection layer reagents.
Ullman, et al. (EP 0 271 204 A2) describe a method of determining the presence of an analyte in a sample which is suspected of containing the analyte consisting of contacting a piece of bibulous material with a test solution containing the sample and a first specific binding pair member analogous to the analog. The material contains a second specific binding pair member capable of binding analyte to the first specific binding pair member. The second specific binding pair member is non-diffusively bound to the bibulous material at least at a portion thereof between the contact portion and a small situs on the piece separated from the contact portion. The surface area of the situs is substantially less than the material. The situs is capable of binding the first specific binding pair member not bound to the second specific binding pair member. The test solution is allowed to traverse the material by means of capillary migration and contact the situs. The situs is then examined for the presence of a specific binding pair member which is usually indicated by the presence of a detectable signal. The patent discloses that the signal can be directly detectable or the situs can be exposed to a signal producing means capable of interacting with the first specific binding pair member to produce a detectable signal at the situs in relation to the amount of analyte in the sample. May, et al. (E.P. 0 291 194 A1) disclose an analytical test device comprised of a hollow casing containing a dry porous carrier which communicates with the exterior of the casing such that a sample can be applied to the carrier. The device also contains a labeled specific binding reagent for an analyte which is freely mobile within the carrier. The device further contains an unlabeled specific binding reagent for the same analyte which is permanently immobilized in a detection zone on the carrier. The labeled reagent and detection zone are positioned such that when a liquid sample is applied to the device it can pick up the labeled reagent and thereafter permeate into the detection zone. The device also incorporates a means for indicating the extent, if any, to which the labeled reagent becomes bound in the detection zone. The binding of the labeled reagent can be observed by the user. The patent discloses that a plurality of detection zones arranged in a series on the porous solid phase material, through which the aqueous liquid sample can pass progressively, can also be used to provide a quantitative measurement of the analyte.
Ching, et al. (EP 299 428 A2) describe assay methods and devices utilizing colloidal particle labeled binding materials which are chromatographically mobile and capable of producing visual detectable signals. The method includes contacting the sample with a chromatographic medium having at least one reaction site which includes an immobilized reagent capable of binding a colloidal particle labeled material (which is capable of producing a detectable response) and the substance in the sample. The colloidal particle labeled material is transported on the chromatographic medium such that a portion of the material is transported to the reaction site and is bound thereto. The method that is taught in the patent is concluded by determining the detectable response produced by the colloidal material at the react
Malick Adrien Paul
McFarland Edward Charles
Becton Dickinson and Company
Housel James
Nelson Brett
Weintraub, Esq. Bruce S.
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