Chemistry: analytical and immunological testing – Involving diffusion or migration of antigen or antibody
Reexamination Certificate
1999-12-13
2003-03-25
Chin, Christopher L. (Department: 1641)
Chemistry: analytical and immunological testing
Involving diffusion or migration of antigen or antibody
C422S051000, C422S051000, C422S051000, C422S051000, C422S067000, C435S287100, C435S287200, C435S287700, C435S287900, C435S805000, C435S810000, C435S970000, C436S518000, C436S530000, C436S169000, C436S805000, C436S810000
Reexamination Certificate
active
06537828
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an immunoassay device in which a chromatography strip is used. More particularly, it relates to an immunoassay device which comprises a chromatography strip having a substrate adhered to the under surface thereof and a protective laminate adhered to the top surface thereof, wherein a space is arranged on the top and/or under surface of at least a partial region of a coloring region of said chromatography strip.
PRIOR ART
As is well known, in an immunoassay device having a chromatography strip, a system is arranged so that an added sample solution to be tested can move in the chromatography strip by the force of capillary flow, and a detecting region of an analyte is arranged on a downstream part of a region where the sample solution is added. The detecting region is arranged in such a manner that it develops a color or its coloring degree is reduced when a sample solution arrived thereto contains an analyte, so that the presence or quantity of the analyte can be detected or measured based on the coloring degree of the detecting region. Such a type of immunoassay device has been described for example in JP-A-61-145459 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-64-32169, JP-A-1-113662, JP-A-1-244370, J-PA-1-63865 and JP-W-1-503174 (the term “JP-W” as used herein means an “unexamined published Japanese international patent application”), and these descriptions are included herein as a part of the description of the present invention.
Each of these immunoassay devices has a chromatography strip in which a substrate is adhered to the under surface thereof and a protective laminate is adhered to the top surface thereof, in order to protect the chromatography strip and prevent biohazard.
According to a study conducted by the inventors of the present invention, it has been found that the capillary flow of sample solution is not uniform in a region of a chromatography strip where analytical reagents are immobilized such as a coloring region. When the flow of a sample solution is not uniform in a coloring region, development of color in the coloring region becomes so irregular that white spots and the like are formed in the coloring region, thus causing reduction of the detection accuracy.
As an attempt to unify capillary flow of a sample solution through a chromatography strip, a technique is disclosed in Patent Publication No. 2590055 in which both ends of a chromatography strip in its longitudinal direction are made into a continuous dentate (concave-convex) shape, but this is not an attempt to unify the flow in the coloring region.
PROBLEMS TO BE RESOLVED BY THE INVENTION
In consequence, the object of the present invention is to provide an immunoassay device in which a chromatography strip is used in such a manner that capillary flow of a sample solution in its coloring region becomes uniform.
MEANS FOR RESOLVING THE PROBLEMS
The inventors of the present invention have found that white spots and the like problems caused by irregular capillary flow in a coloring region do not occur and high detection accuracy can be obtained when a space is arranged in at least a partial region of the coloring region in a chromatography strip which has a substrate adhered to the under surface thereof and a protective laminate adhered to the top surface thereof. Accordingly, the present invention is an immunoassay device which comprises a chromatography strip having a substrate adhered to the under surface thereof and a protective laminate adhered to the top surface thereof, wherein a space is arranged on the top and/or under surface of at least a partial region of a coloring region of the chromatography strip.
MODE OF CARRYING OUT THE INVENTION
As shown in
FIG. 1
, the immunoassay device of the present invention has a chromatography strip (
1
) in which a substrate (
2
) is adhered to its under surface and a protective laminate (
3
) is adhered to its top surface.
As the chromatography carrier of the chromatography strip, any of those which are known in this field can be used. For example, cellulose, nitrocellulose, cellulose acetate and the like are used most frequently.
The substrate and protective laminate are adhered to the chromatography strip by applying a paste (
4
) to the substrate and protective laminate. For example, a rubber, acrylic, vinyl ether polymer or the like adhesive is used as the paste.
When nitrocellulose or the like carrier which is soluble in organic solvents is used as the chromatography carrier, the chromatography carrier and the substrate may be adhered by dissolving nitrocellulose in an organic solvent such as acetone or the like and spreading the solution on a substrate composed of polyethylene terephthalate or the like film which is soluble in the solvent or on a substrate having the same film. Such a case is also included in the adhering of the chromatography strip to the substrate of the present invention.
The substrate and protective laminate may be those which are usually used in the conventional immunoassay devices in which chromatography strips are employed. For example, polyethylene terephthalate, polypropylene, polyvinyl chloride and the like may be used.
The chromatography strip has a sample applying region (
5
), and when a sample solution having a possibility of containing an analyte is applied to the sample applying region, the sample solution moves to the downstream direction by the force of capillary flow.
The chromatography strip also has a coloring region at a downstream position of the sample applying region. The coloring region is a region which develops color during the assay, and it includes a detecting region (
6
) for detecting an analyte in a sample solution. As occasion demands, a control region (
7
) may be arranged as a coloring region.
The detecting region is arranged in such a manner that a tracer comprised of a labeled antigen or antibody is accumulated in response to the presence or quantity of an analyte contained in a sample solution which is migrated form the upstream area by the force of capillary flow. The term “in response to the presence or quantity of an analyte” as used herein means that the amount of accumulated tracer increases in the case of a sandwich assay or the amount of accumulated tracer decreases in the case of a competitive assay. That is, the detecting region contains an immobilized compound to which, if necessary via a certain crosslinking compound, an analyte specifically binds (in this case, a tracer binds specifically to the analyte also) or specifically binds in competition with the tracer.
The term “crosslinking compound” as used herein means a substance which binds specifically to both of the compound immobilized to the detecting region and an analyte. For example, there is a case in which an anti-mouse IgG antibody is immobilized to the detecting region and a mouse IgG for an analyte antigen is used as the crosslinking compound. Also, it is possible to use, as the crosslinking compound, a conjugate composed of a compound which specifically binds to the compound immobilized to the detecting region and a substance that specifically binds to an analyte. In this case, the substance that specifically binds to an analyte may be an antibody when the analyte is an antigen, or an antigen when the analyte is an antibody. The combination of a compound immobilized to the detecting region and a compound which specifically binds to the compound immobilized to the detecting region may be biotin as one and anti-biotin antibody or avidin as the other, or a saccharide as one and a saccharide-binding protein as the other.
When an analyte and a tracer competitively bind to the compound immobilized to the detecting region, a second detecting region may be arranged at a position downstream of the detecting region, in order to capture the tracer which has not been captured at the detecting region. This second detecting region is also included in the “detecting region” of the present invention.
Examples of the marker to be used in
Chiba Ryotaro
Nakaya Miho
Chin Christopher L.
Dainabot Co., Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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