阅读说明：本技术 树脂-铂复合体及其利用 (Resin-platinum composite and use thereof ) 是由 松村康史 榎本靖 于 2016-07-07 设计创作，主要内容包括：本发明提供一种树脂-铂复合体及其利用,所述树脂-铂复合体(100)包括树脂粒子(10)及铂粒子(20),且将铂粒子(20)固定于树脂粒子(10)上。树脂-铂复合体(100)中,铂粒子(20)的一部分可在树脂粒子(10)的表层部(60)中三维地分布。在所述情形时,三维地分布的铂粒子(20)的一部分可局部地在树脂粒子(10)外露出,其余的一部分可内包于树脂粒子(10)内。铂粒子(20)中,优选为存在完全内包于树脂粒子(10)内的内包粒子(30)、具有包埋于树脂粒子(10)内的部位及在树脂粒子(10)外露出的部位的局部露出粒子(40)、及吸附于树脂粒子(10)的表面的表面吸附粒子(50)。(The resin-platinum composite (100) includes resin particles (10) and platinum particles (20), and the platinum particles (20) are fixed to the resin particles (10). In the resin-platinum composite (100), a part of the platinum particles (20) can be distributed three-dimensionally in the surface layer part (60) of the resin particles (10). In this case, a part of the three-dimensionally distributed platinum particles (20) may be partially exposed to the outside of the resin particles (10), and the remaining part may be contained in the resin particles (10). Preferably, the platinum particles (20) include encapsulated particles (30) completely encapsulated in the resin particles (10), partially exposed particles (40) having portions embedded in the resin particles (10) and portions exposed to the outside of the resin particles (10), and surface-adsorbed particles (50) adsorbed on the surfaces of the resin particles (10).)

1. A resin-platinum composite body comprising:

Resin particles, and

A plurality of platinum particles smaller than the resin particles, and

The platinum particles are fixed to the resin particles, and include platinum particles having a portion embedded in the resin particles and a portion exposed to the outside of the resin particles.

2. The resin-platinum composite body according to claim 1, wherein at least a part of the platinum particles are three-dimensionally distributed in a surface layer portion of the resin particles.

3. The resin-platinum composite body according to claim 2, wherein 60 wt% to 100 wt% of the plurality of platinum particles are present in the surface layer portion.

4. The resin-platinum composite body according to claim 1, wherein the platinum particles are fixed to the surface of the resin particles without overlapping in the radial direction of the resin particles.

5. The resin-platinum composite according to claim 1, wherein the platinum particles have an average particle diameter in a range of 1nm to 80 nm.

6. The resin-platinum composite according to claim 5, wherein the average particle diameter is in the range of 50nm to 1000 nm.

7. The resin-platinum composite according to claim 1, wherein the platinum particles have an average particle diameter in a range of 1nm to 50 nm.

8. The resin-platinum composite according to claim 1, wherein the platinum particles have an average particle diameter in a range of 1nm to 30 nm.

9. The resin-platinum composite according to claim 1, wherein the platinum particles have an average particle diameter in a range of 1nm to 15 nm.

10. The resin-platinum composite according to claim 7, wherein the average particle diameter is in the range of 100nm to 600 nm.

11. The resin-platinum composite body according to claim 1, wherein a loading amount of the platinum particles is in a range of 5 wt% to 70 wt% with respect to a weight of the resin-platinum composite body.

12. The resin-platinum composite body according to claim 1, wherein the resin particles are polymer particles having a substituent capable of adsorbing platinum ions in the structure.

13. a labeling substance comprising the resin-platinum complex according to claim 1.

14. The labeling substance according to claim 13, which is used by adsorbing an antigen or an antibody to the surface of the resin-platinum complex.

15. An immunological assay using the labeling substance according to claim 13.

16. A reagent for immunological assay, comprising the resin-platinum complex according to claim 1.

17. A method for measuring an analyte, which detects or quantifies the analyte contained in a sample, characterized in that:

Performing steps including steps (I) to (III) using a lateral flow chromatography test strip including a membrane and a determination section in which a capture ligand that specifically binds to the analyte is immobilized on the membrane;

Step (I): a step of bringing the analyte contained in a sample into contact with a labeled antibody, wherein the labeled antibody is obtained by labeling an antibody that specifically binds to the analyte with the resin-platinum complex according to claim 1;

Step (II): a step of bringing the complex containing the analyte and the labeled antibody formed in step (I) into contact with a capture ligand in the determination unit;

Step (III): and measuring the localized surface plasmon resonance of the resin-platinum complex and the color intensity derived from the absorption of optical energy by electron transfer.

18. An analyte measurement kit for detecting or quantifying an analyte contained in a sample using a lateral flow type chromatography test strip, comprising:

A lateral flow type chromatographic test strip comprising a membrane and a judgment part formed by fixing a capture ligand specifically binding to the analyte on the membrane; and

A detection reagent comprising a labeled antibody, wherein the labeled antibody is obtained by labeling an antibody that specifically binds to the analyte with the resin-platinum complex according to claim 1.

19. A lateral flow chromatography test strip for detecting or quantifying an analyte contained in a sample, comprising:

A film;

A determination unit configured to immobilize a capture ligand that specifically binds to the analyte on the thin film in a direction in which the sample is developed; and

A reaction part located upstream of the determination part and containing a labeled antibody labeled with an antibody that specifically binds to the analyte according to the resin-platinum complex of claim 1.

Technical Field

The present invention relates to a resin-platinum complex which can be preferably used for applications such as immunological assays, and a labeling substance using the same, an immunological assay method, a reagent for immunological assay, a method for measuring an analyte (analyte), a kit for measuring an analyte, and a lateral flow chromatography test strip (test strip).

Background

Since there are an infinite number of chemical substances in a living body, it is an extremely important technique to qualitatively and quantitatively analyze specific trace components in a living body. In the fields of medical treatment, pharmaceutical preparation, health food, biotechnology (biotechnology), environment, and the like, there have been developed medicines and foods that act only on specific sites (chemical substances) in the living body, analyzers and diagnostic agents that detect slight changes in the living body, and the like.

As one of the analysis techniques, there is an immunoassay (immunological). This is also called an immunoassay, and is a method for qualitatively and quantitatively analyzing a trace component by utilizing an antigen-antibody specific reaction which is one of immune reactions. Antigen-antibody reactions are widely used in the field because of their high sensitivity and selectivity. Immunoassay has various assays according to its assay principle. Examples thereof include: enzyme Immunoassay (EIA), Radioimmunoassay (RIA), chemiluminescence Immunoassay (CLIA), Fluorescence Immunoassay (FIA), coagulation methods (Latex coagulation, LIA) of Latex (Latex), etc. (ICA), Immunochromatography (agglutination, ICA), Hemagglutination (HA), inhibition of erythrocyte coagulation (HI), etc. In addition to immunoassays, there are physical/chemical assays, biological assays, and the like.

In the immunoassay, an antigen or an antibody is qualitatively or quantitatively detected based on a change in the formation of a complex by the reaction of the antigen and the antibody (a change in the concentration of the antigen, the antibody, or the complex). When these substances are detected, the detection sensitivity is increased by binding the labeled substance to the antibody, antigen, or complex.

therefore, the labeling ability of the labeling substance can be said to be an important factor affecting the detection ability of the immunoassay. In the above-described exemplified immunoassay, red blood cells (in the case of HA), latex particles (in the case of LIA), fluorescent dye (in the case of FIA), radioactive element (in the case of RIA), enzyme (in the case of EIA), chemiluminescent substance (in the case of CLIA), and the like can be used as the labeling substance.

However, when colored fine particles are used as the labeling substance, detection can be confirmed visually without using a special analysis device, and thus simpler measurement is expected. Examples of such colored fine particles include colloidal particles of metal and metal oxide, and latex particles colored with a pigment (patent documents 1 and 4). However, the colloidal particles have the following problems because the color tone is determined by the particle size and the production conditions: it is difficult to obtain a desired vivid deep color tone, i.e., visibility is insufficient.

In addition, the colored latex particles have the following problems: the coloring effect obtained by the coloring matter is low, and the visual judgment is insufficient. Further, if the amount of coloring with a coloring agent is to be increased in order to solve the above-mentioned problems, there are the following problems: since the pigment covers the surface of the latex and the original surface state of the latex particles is impaired, it is difficult to bind the antigen or the antibody. In addition, there are also the following problems: clogging occurs in pores of a chromatography medium such as a membrane filter; or the latex particles are subjected to nonspecific coagulation; or deeply colored by adding a coloring material of a pigment, but this is not always related to the improvement of the performance.

In order to improve the visibility of the labeling substance, the following immunochromatography method is disclosed: after an antibody (labeled antibody) to which a labeling substance has been bound reacts with an antigen to form a complex, the labeling substance is further modified with another metal, thereby increasing the detection sensitivity of the labeling substance (patent documents 2 and 5). However, the method is complicated in operation and difficult to stably increase. Further, since a special device or the like is required and the measurement cost is high, the applicable use and use environment are considered to be limited.

Further, a colored latex including gold nanoparticles bonded to the surface of polymer-based latex particles is disclosed (patent document 3).

Since the gold nanoparticles themselves function as a coloring agent to improve the visual determination property or the detection sensitivity by binding to the surface of the polymer-based latex particles, and the gold nanoparticles themselves have excellent binding properties to an antigen or an antibody, a sufficient amount of the antigen or the antibody can be bound even when the gold nanoparticles are bound to a sufficiently deep color.

The colored latex is obtained by irradiating a dispersion of a styrene-acrylic copolymer latex and HAuCl, which is a precursor of gold nanoparticles, with gamma rays, thereby bonding the gold nanoparticles to the surface of the latex. However, since the colored latex is formed by bonding gold nanoparticles only on the surface of the latex, the amount of gold particles exhibiting surface plasmon resonance is limited, and the gold nanoparticles are easily detached. As a result, the reagent for immunological measurement may have insufficient visibility or sensitivity. In addition, the latex may be damaged by irradiation with electromagnetic radiation such as γ rays. Further, the specification of patent document 3 discloses preferred ranges of the latex particle size and the gold nanoparticle size, but does not indicate whether or not the preferred ranges are verified in the examples, and is not a basis for defining the preferred ranges.

Patent document 4 discloses a polymer latex particle coated with gold metal, and suggests that the polymer latex particle is applied to a reagent that can be used in a microscopic method or an immunoassay method.

However, the material and particle size of the polymer latex particles are not disclosed with respect to the metal gold-coated polymer latex particles. Furthermore, the effect as a reagent usable in the immunoassay method was not verified. Therefore, the effect of metallic gold and polymer latex particles as a reagent is not known.

Non-patent document 1 discloses a microgel in which gold nanoparticles are supported on poly-2-vinylpyridine latex particles, and the pH responsiveness of the particle diameter of the microgel is confirmed from the change in behavior of localized surface plasmon resonance of the gold nanoparticles. However, in the microgel, gold nanoparticles are supported in a single layer in the vicinity of the surface layer of the latex particles. Therefore, it is considered that the amount of gold nanoparticles carried is small and a deep color tone effective for immunoassay cannot be obtained. In addition, the material, structure, composition and the like of the microgel are not studied, and the effect on specific applications such as an immunological assay reagent is not known.

From the above, latex particles to which gold nanoparticles are bonded or coated are expected as a reagent for immunological measurement, but the durability and visibility are insufficient in the conventional techniques. Further, even if visibility is high, the applicable use and use environment are limited.

Disclosure of Invention

Problems to be solved by the invention

In order to use the resin-metal complex as a labeling substance in an immunological assay, it is necessary to stably bind the complex to a ligand (ligand) such as an antibody. However, when a ligand is labeled with a resin-metal complex, even if a stable binding state can be formed, excellent detection sensitivity is not necessarily obtained. For example, fine resin-metal composites are prone to aggregation. When the aggregation occurs, not only the operability is greatly reduced, but also the detection sensitivity is greatly reduced due to the occurrence of variation in the concentration of the resin-metal composite as the labeling substance.

The present invention aims to provide a resin-metal complex which is less likely to aggregate in a state of being bound to a ligand such as an antibody and has excellent handling properties, and for example, the present invention aims to provide a resin-metal complex for immunoassay which can be determined with high sensitivity in immunoassay.

Means for solving the problems

The present inventors have conducted intensive studies and, as a result, have found that the above problems can be solved by a resin-platinum composite in which a plurality of platinum particles are fixed to resin particles, and have completed the present invention.

That is, the resin-platinum composite of the present invention includes a resin particle and a plurality of platinum particles smaller than the resin particle, and the plurality of platinum particles are fixed to the resin particle.

In the resin-platinum composite of the present invention, at least some of the platinum particles may be three-dimensionally distributed in the surface layer portion of the resin particles. In this case, 60 wt% to 100 wt% of the plurality of platinum particles may be present in the surface layer portion.

In the resin-platinum composite of the present invention, the platinum particles may be fixed to the surface of the resin particles without overlapping in the radial direction of the resin particles.

In the resin-platinum composite of the present invention, the average particle diameter of the platinum particles may be in the range of 1nm to 80 nm. In such a case, the average particle diameter of the resin-platinum composite may be in the range of 50nm to 1000 nm.

In the resin-platinum composite of the present invention, the platinum particles preferably have an average particle diameter in the range of 1nm to 50nm, more preferably in the range of 1nm to 30nm, and most preferably in the range of 1nm to 15 nm. In these cases, the average particle diameter of the resin-platinum composite is preferably in the range of 100nm to 600 nm.

In the resin-platinum composite of the present invention, the amount of the platinum particles may be in the range of 5 to 70 wt% based on the weight of the resin-platinum composite.

In the resin-platinum composite of the present invention, the resin particles may be polymer particles having a substituent capable of adsorbing platinum ions in the structure.

The labeling substance of the present invention includes any of the resin-platinum complexes. In such a case, an antigen or an antibody may be adsorbed to the surface of the resin-platinum complex.

The immunological assay method of the present invention uses any of the above-mentioned labeling substances.

The reagent for immunological assay of the present invention includes any of the above resin-platinum complexes.

The method for measuring an analyte of the present invention is a method for detecting or quantifying an analyte contained in a sample. Wherein: performing steps including steps (I) to (III) using a lateral flow chromatography test strip including a membrane (membrane) and a determination section in which a capture ligand that specifically binds to the analyte is immobilized on the membrane;

step (I): a step of bringing the analyte contained in the sample into contact with a labeled antibody, wherein the labeled antibody is obtained by labeling an antibody that specifically binds to the analyte with any one of the resin-platinum complexes;

Step (II): a step of bringing the complex containing the analyte and the labeled antibody formed in step (I) into contact with a capture ligand in the determination unit;

Step (III): and measuring the localized surface plasmon resonance of the resin-platinum complex and the color intensity derived from the absorption of optical energy by electron transfer.

The analyte measurement kit of the present invention is an analyte measurement kit for detecting or quantifying an analyte contained in a sample using a lateral flow type chromatography test strip. The kit for analyte measurement includes: a lateral flow type chromatographic test strip comprising a membrane and a judgment part formed by fixing a capture ligand specifically binding to the analyte on the membrane; and a detection reagent containing a labeled antibody, wherein the labeled antibody is formed by labeling an antibody which specifically binds to the analyte with any one of the resin-platinum complexes.

The test strip for lateral flow chromatography of the present invention is used for detecting or quantifying an analyte contained in a sample. The lateral flow type chromatographic test strip includes: a film; a determination unit configured to immobilize a capture ligand that specifically binds to the analyte on the thin film in a direction in which the sample is developed; and a reaction section located upstream of the determination section and containing a labeled antibody labeled with an antibody that specifically binds to the analyte using any of the resin-platinum complexes.

ADVANTAGEOUS EFFECTS OF INVENTION

The resin-platinum complex of the present invention has excellent dispersibility in a state of being bound to a ligand such as an antibody, for example, and is less likely to aggregate. In addition, since the resin-platinum composite of the present invention has a structure in which a plurality of platinum particles are fixed to resin particles, the amount of platinum particles supported is large, and the platinum particles are not easily detached from the resin particles. In addition, the platinum particles exhibit light energy absorption due to electron transfer in addition to localized surface plasmon resonance. Therefore, the resin-platinum complex of the present invention can be preferably used as a material having excellent handling properties, durability, visibility, visual judgment properties, and detection sensitivity for the purpose of, for example, labeling materials for immunological measurement such as EIA, RIA, CLIA, FIA, PA, ICA, HA, and HI, reagents for immunological measurement, medicines, solid catalysts, pigments, paints, conductive materials, electrodes, sensor elements, and the like. When the resin-platinum complex of the present invention is used in an immunological assay, the resin-platinum complex is excellent in handling, durability and visibility, and can be determined with high sensitivity without adding a special apparatus or a special operation step.

Drawings

Fig. 1 is a schematic diagram showing a cross-sectional structure of a resin-platinum composite according to an embodiment of the present invention.

Fig. 2A is a schematic diagram showing a cross-sectional structure of one form of the resin-platinum composite.

Fig. 2B is a schematic diagram showing a cross-sectional structure of another embodiment of the resin-platinum composite.

Fig. 3 is an explanatory view showing an outline of a method for measuring an analyte using a lateral flow type chromatography test strip according to an embodiment of the present invention.

FIG. 4 is a photograph showing an example of the results of evaluation of dispersibility of the resin-metal complex labeled antibody.

FIG. 5 is a Scanning Electron Microscope (SEM) photograph of the resin-platinum complex obtained in example 2.

FIG. 6 is a Scanning Transmission Electronic Microscope (STEM) photograph showing a cross section of the resin-platinum composite obtained in example 2.

Description of the symbols

10: resin particle

20: platinum particles

30: encapsulated particles

40: partially exposed particles

50: surface adsorption particles

60: surface layer part

100: resin-platinum composite body

110: film(s)

120: sample addition part

130: determination unit

131: capture ligands

140: liquid suction part

150: labeled antibodies

160: analyte

170: composite body

200: test strip

D1-D3: particle size

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings as appropriate. Fig. 1 is a schematic cross-sectional view of a resin-platinum composite according to an embodiment of the present invention. The resin-platinum composite 100 includes resin particles 10 and platinum particles 20. In the resin-platinum composite 100, platinum particles 20 are fixed to resin particles 10. The resin particles 10 are larger than the platinum particles 20. That is, in the resin-platinum composite 100, a large number of relatively small platinum particles 20 are fixed to a large resin particle 10. As shown in fig. 1, the relationship among the particle diameter D1 of the resin-platinum composite 100 as a whole, the particle diameter D2 of the resin particles 10, and the particle diameter D3 of the platinum particles 20 is D1 > D2 > D3.

In the resin-platinum composite 100, a part of the platinum particles 20 may be three-dimensionally distributed in the surface layer portion 60 of the resin particles 10. In this case, a part of the three-dimensionally distributed platinum particles 20 may be partially exposed outside the resin particles 10, and the remaining part may be contained in the resin particles 10. Specifically, as shown in fig. 1, platinum particles 20 preferably include platinum particles completely contained in resin particles 10 (hereinafter also referred to as "contained particles 30"), platinum particles having portions embedded in resin particles 10 and portions exposed to resin particles 10 (hereinafter also referred to as "partially exposed particles 40"), and platinum particles adsorbed on the surface of resin particles 10 (hereinafter also referred to as "surface adsorbed particles 50").

For example, when the resin-platinum complex 100 is used as a labeling substance for immunological assay or a reagent for immunological assay, an antibody or an antigen is immobilized on the surface of the resin particle 10, or the surface of the particle 40 or the surface adsorption particle 50 is partially exposed. At this time, the antibody or antigen is immobilized on the partially exposed particles 40 and the surface-adsorbed particles 50, but is not immobilized on the encapsulated particles 30. However, since the partially exposed particles 40, the surface-adsorbed particles 50, and the encapsulated particles 30 exhibit absorption of light energy by electron transfer in addition to localized surface plasmon resonance, the encapsulated particles 30 as well as the partially exposed particles 40 and the surface-adsorbed particles 50 contribute to improvement in visibility of the labeling substance for immunoassay and the reagent for immunoassay. Furthermore, the partially exposed particles 40 and the encapsulated particles 30 have a larger contact area with the resin particles 10 than the surface-adsorbed particles 50, and in addition, exhibit a fixing (anchor) effect and the like by the embedded state, and therefore have a strong physical adsorption force and are less likely to be detached from the resin particles 10. Therefore, the labeling substance for immunological measurement and the reagent for immunological measurement using the resin-platinum complex 100 can be made excellent in durability and stability.

Hereinafter, a case where the resin-platinum complex 100 is applied to a labeling substance for immunological assay (hereinafter, also simply referred to as "labeling substance") or a reagent for immunological assay (hereinafter, also simply referred to as "reagent") will be described as an example.

The surface of the inner particle 30 is entirely covered with the resin constituting the resin particle 10. The partially exposed particles 40 have a surface area covered with a resin constituting the resin particles 10 in an amount of 5% or more and less than 100%. The lower limit of the durability of the labeling substance for immunological assay and the reagent for immunological assay is preferably 20% or more, and more preferably 30% or more of the surface area. The surface adsorption particles 50 are preferably covered with the resin constituting the resin particles 10 in an amount of more than 0% and less than 5% of the surface area.

The amount of the platinum particles 20 (the total of the encapsulated particles 30, the partially exposed particles 40, and the surface-adsorbing particles 50) supported on the resin-platinum composite 100 is preferably 5 to 70 wt% based on the weight of the resin-platinum composite 100. When the amount is within the above range, the resin-platinum composite 100 is excellent in visibility, visual judgment, and detection sensitivity as a labeling substance. When the amount of the platinum particles 20 supported is less than 5 wt%, the amount of the antibody or antigen immobilized tends to be small, and the detection sensitivity tends to be low. The supporting amount of the platinum particles 20 is more preferably 15 to 70 wt%, and still more preferably 15 to 60 wt%. Further, the resin-platinum composite 100 containing the platinum particles 20 can be used as a labeling substance having excellent visibility, visual judgment, and detection sensitivity even in a smaller amount than other metal particles (for example, a resin-gold composite containing gold particles).

Preferably, 10 wt% to 90 wt% of the platinum particles 20 are partially exposed particles 40 and surface adsorbed particles 50. When the amount is within the above range, the amount of the antibody or antigen immobilized on the platinum particles 20 can be sufficiently secured, and thus the sensitivity as a labeling substance is high. More preferably, 20 to 80 wt% of the platinum particles 20 is the partially exposed particles 40 and the surface-adsorbed particles 50, and still more preferably, the surface-adsorbed particles 50 are 20 wt% or less in view of durability of the labeling substance for immunoassay and the reagent for immunoassay.

When the resin-platinum complex 100 is used in an immunological assay, in order to obtain excellent detection sensitivity, it is preferable that 60 to 100 wt%, preferably 75 to 100 wt%, and more preferably 85 to 100 wt% of the platinum particles 20 be present in the surface layer portion 60, and it is more preferable that the platinum particles be present in a range of 40% of the particle radius in the depth direction from the surface of the resin particles 10. In addition, when 5 wt% to 90 wt% of the platinum particles 20 present in the surface layer portion 60 are partially exposed particles 40 or surface-adsorbed particles 50, the amount of the antibody or antigen immobilized on the platinum particles 20 can be sufficiently secured, and thus the sensitivity as a labeling substance is preferably high. In other words, it is preferable that 10 wt% to 95 wt% of the platinum particles 20 present in the surface layer portion 60 be the inner particle 30.

The "surface portion" referred to herein is a range of 50% of the particle radius in the depth direction from the surface of the resin particle 10, based on the outermost position of the resin-platinum composite 100 (i.e., the protruding end portion of the partially exposed particle 40 or the surface adsorbed particle 50). The term "three-dimensionally distributed" means that the platinum particles 20 are dispersed not only in the plane direction but also in the depth direction of the resin particles 10.

As described above, since the encapsulated particles 30 exhibit absorption of light energy by electron transfer in addition to localized surface plasmon resonance, the encapsulated particles 30 contribute to improvement in visibility of the labeling substance for immunoassay and the reagent for immunoassay as well as to partial exposure of the particles 40 and the surface-adsorbed particles 50. From the viewpoint of such improvement in visibility, it is preferable that the resin-platinum composite 100 is configured such that, for example, as shown in fig. 2A, the encapsulated particles 30 are distributed in a concentrated manner in a certain range in the depth direction from the surface of the resin particle 10, and the encapsulated particles 30 are not present in the vicinity of the center of the resin particle 10. More specifically, in order to effectively exhibit absorption of light energy by electron transfer in addition to localized surface plasmon resonance by the inclusion particles 30, for example, when the particle diameter D2 of the resin particle 10 is 800nm, it is preferable that 70 wt% or more, preferably 80 wt% or more, and more preferably 90 wt% to 100 wt% of the inclusion particles 30 are present in the range of, for example, 0nm to 200nm in the depth direction from the surface of the resin particle 10. Particularly, in the case where the region (inner particle distribution region) in which all the inner particles 30(100 wt%) are distributed is in the range of, for example, 0nm to 100nm from the surface of the resin particle 10, it is preferable because the expression of optical energy absorption by electron transfer can be maximized in addition to localized surface plasmon resonance obtained by the inner particles 30.

The resin-platinum composite 100 may not have the encapsulated particles 30. For example, as shown in fig. 2B, in the resin-platinum composite 100, all the platinum particles 20 may be fixed to the surface of the resin particle 10 without overlapping in the radial direction of the resin particle 10. In this case, the platinum particles 20 include the partially exposed particles 40 and the surface adsorption particles 50.

the resin particles 10 are preferably polymer particles having a substituent capable of adsorbing platinum ions in the structure. Particularly preferred are nitrogen-containing polymer particles. The nitrogen atom in the nitrogen-containing polymer is preferred because it readily chemisorbs anionic ions such as [ PtCl6]2-, which is a precursor of the platinum particles 20 having excellent visibility and easily immobilizing an antigen or an antibody. In the present embodiment, since platinum particles 20 are formed by reducing platinum ions adsorbed in a nitrogen-containing polymer, a part of the formed platinum particles 20 becomes encapsulated particles 30 or partially exposed particles 40. Further, a carboxylic acid group-containing polymer such as an acrylic polymer and a sulfonic acid group-containing polymer such as polystyrene sulfonic acid (hereinafter collectively referred to as "cationic ion-adsorbable polymer") are preferable because cationic ions such as Pt2+ can be chemisorbed by the carboxylic acid groups and sulfonic acid groups contained therein. For example, the platinum particles 20 can be formed by reducing the chemisorbed Pt2+, thereby producing the same structure as the nitrogen-containing polymer particles. Further, it is preferable because, for example, cationic ions which are precursors of metals such as silver, nickel, and copper are easily adsorbed, and an alloy with platinum can be produced by using these polymers.

On the other hand, in the case of resin particles other than nitrogen-containing polymers having a structure having a substituent capable of adsorbing platinum ions, for example, polystyrene, it is difficult to adsorb the platinum ions into the resin. As a result, most of the generated platinum particles 20 become surface adsorption particles 50. As described above, since the contact area between the surface adsorption particles 50 and the resin particles 10 is small, the adhesion force between the resin and the metal is small, and the influence of the platinum particles 20 being detached from the resin particles 10 tends to be large.

the nitrogen-containing polymer is a resin having a nitrogen atom in a main chain or a side chain, and examples thereof include polyamine, polyamide, polypeptide, polyurethane, polyurea, polyimide, polyimidazole, polyoxazol, polypyrrole, polyaniline, and the like. Polyamines such as poly-2-vinylpyridine, poly-3-vinylpyridine, and poly-4-vinylpyridine are preferred. In the case where the side chain has a nitrogen atom, for example, acrylic resins, phenol resins, epoxy resins, and the like are widely used.

The polymer capable of adsorbing cationic ions is a resin having a carboxylic acid group, a sulfonic acid group, or the like in the main chain or side chain, and for example, polyacrylic acid, vinyl carboxylate, polyvinyl acetate, polyvinyl sulfonic acid, polystyrene sulfonic acid, or the like is widely used.

The nitrogen-containing polymer and the polymer capable of adsorbing cationic ions may be copolymers with known polymerizable monomers. Examples of the copolymer include a random copolymer, a block copolymer, an alternating copolymer, and a copolymer in which polymers are crosslinked with each other. Further, two or more monomers may be copolymerized to form the resin particle 10, or the monomers may be reacted with functional groups present on the surface of the resin particle 10 to further polymerize the functional groups as polymerization active terminals. The copolymerization composition is not limited, and it is preferable that the monomer having a substituent capable of adsorbing platinum ions is 10 mol% or more.

The resin-platinum complex 100 having the platinum particles 20 is less likely to aggregate in a state of being bound to a ligand such as an antibody than a resin complex having particles of another metal species, and has extremely excellent dispersibility. Further, the platinum particles 20 have high resistance to changes such as oxidation and excellent storage stability. Further, the platinum particles 20 exhibit absorption due to localized surface plasmon resonance at a wide wavelength range of 250nm to 900nm, for example, and further exhibit light energy absorption by electron transfer to exhibit strong color development close to black, so that high visibility can be obtained in an immunological assay and the detection sensitivity of an analyte can be improved by using the resin-platinum complex 100 as a labeling substance. In this case, by using the platinum particles 20, it is possible to obtain excellent detection sensitivity with a smaller loading amount than particles of other metals (e.g., gold). Therefore, if the average particle diameter is the same, the resin-platinum composite 100 exhibits significantly higher detection sensitivity than a resin composite having particles of another metal species.

The platinum particles 20 may contain only platinum, or may be an alloy of platinum with another metal. The platinum alloy contains platinum and a metal species other than platinum, and means an alloy containing 1 wt% or more of platinum. Here, the kind of other metal to be alloyed with platinum is not particularly limited, and is preferably silver, nickel, copper, gold, palladium, or the like, and more preferably gold, palladium, or the like, which is excellent in storage stability and visibility.

The average particle diameter of the platinum particles 20 (i.e., the average value of the particle diameters D3 in fig. 1) measured by observation with a Scanning Electron Microscope (SEM) is preferably, for example, 1nm to 80 nm. When the average particle diameter of the platinum particles 20 is less than 1nm or more than 80nm, localized surface plasmon resonance and absorption of light energy by electron transfer are not easily exhibited, and thus the sensitivity tends to be lowered. From the viewpoint of obtaining high detection sensitivity when the resin-platinum complex 100 is used in an immunological assay, the average particle diameter of the platinum particles 20 is preferably 1nm or more and 50nm or less, more preferably 1nm or more and 30nm or less, still more preferably 1nm or more and 20nm or less, and most preferably 1nm or more and 15nm or less. Particularly, when the average particle diameter of the platinum particles 20 is 15nm or less, particularly excellent detection sensitivity can be obtained when the resin-platinum complex 100 is used as a labeling substance for immunochromatography.

The average particle diameter of the resin-platinum composite 100 (i.e., the average value of the particle diameters D1 in fig. 1) is preferably 50nm to 1000nm, for example. If the average particle size of the resin-platinum composite 100 is less than 50nm, for example, the amount of platinum particles supported tends to be small, so that the coloration tends to be weak compared with platinum particles of the same size, and if it exceeds 1000nm, the pores of a chromatography medium such as a membrane filter tend to be easily clogged or the dispersibility tends to be reduced when a labeling substance or a reagent is produced. From the viewpoint of improving dispersibility when a labeling substance or a reagent is prepared and obtaining high detection sensitivity when the resin-platinum complex 100 is used in an immunological assay, the average particle diameter of the resin-platinum complex 100 is preferably 100nm or more and 600nm or less, more preferably 250nm or more and 600nm or less, and most preferably 300nm or more and 600nm or less. In particular, when the average particle diameter of the resin-platinum complex 100 is 300nm or more, excellent detection sensitivity can be stably obtained when the resin-platinum complex 100 is used as a labeling substance for immunochromatography. Here, the particle diameter of the resin-platinum composite 100 is a value obtained by adding the particle diameter of the resin particle 10 to the length of the protruding portion where the particle 40 is partially exposed or the particle 50 is adsorbed on the surface, and can be measured by a laser diffraction/scattering method, a dynamic light scattering method, or a centrifugal sedimentation method.

[ method for producing resin-platinum Complex ]

The method for producing the resin-platinum composite 100 is not particularly limited. For example, a solution containing platinum ions is added to a dispersion of resin particles 10 produced by an emulsion polymerization method, and platinum ions are adsorbed to the resin particles 10 (hereinafter referred to as "platinum ion-adsorbing resin particles"). Further, the platinum ion-adsorbing resin particles are added to a reducing agent solution, thereby reducing platinum ions to produce platinum particles 20, and a resin-platinum composite 100 is obtained.

Examples of the solution containing platinum ions include an aqueous solution of platinic chloride (H2PtCl6) and a solution of platinum chloride (PtCl 2). In addition, platinum complexes may also be used instead of platinum ions.

In addition, the following solvents may also be used as the solvent of the solution containing platinum ions, instead of water: aqueous alcohols or alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and tert-butanol, acids such as hydrochloric acid, sulfuric acid and nitric acid, and the like.

in addition, if necessary, a water-soluble polymer compound such as polyvinyl alcohol, a surfactant, an alcohol; ethers such as tetrahydrofuran, diethyl ether and diisopropyl ether; polyhydric alcohols such as alkylene glycols, polyalkylene glycols, monoalkyl ethers or dialkyl ethers of these glycols, and glycerin; and various water-miscible organic solvents such as ketones, e.g., acetone and methyl ethyl ketone. Such an additive is effective in promoting the reduction reaction rate of platinum ions and controlling the size of the platinum particles 20 to be produced.

In addition, a known reducing agent can be used. Examples thereof include: sodium borohydride, dimethylamine borane, citric acid, sodium hypophosphite, hydrazine hydrate, hydrazine hydrochloride, hydrazine sulfate, formaldehyde, sucrose, glucose, ascorbic acid, isoascorbic acid, sodium phosphinate, hydroquinone, Rochelle salt (Rochelle salt), and the like. Among them, sodium borohydride, dimethylamine borane and citric acid are preferable.

As for the reducing agent solution, a surfactant may be added as necessary, or the pH of the solution may be adjusted. The pH can be adjusted by using a buffer such as boric acid or phosphoric acid, an acid such as hydrochloric acid or sulfuric acid, or a base such as sodium hydroxide or potassium hydroxide.

Further, the particle diameter of the formed platinum particles 20 can be controlled by adjusting the reduction rate of the platinum ions by the temperature of the reducing agent solution.

In addition, in the case of reducing platinum ions in the platinum ion-adsorbing resin particles to produce platinum particles 20, the platinum ion-adsorbing resin particles may be added to a reducing agent solution, or a reducing agent may be added to the platinum ion-adsorbing resin particles, but the former is preferable in terms of ease of production of the included particles 30 and the partially exposed particles 40.

In order to maintain the dispersibility of the resin-platinum composite 100 in water, a dispersant such as citric acid, poly-L-lysine, polyvinylpyrrolidone (polyvinylpyrollidone), polyvinylpyridine, polyvinyl alcohol, DISPERBYK (DISPERBYK)194, DISPERBYK (DISPERBYK)180, and DISPERBYK (DISPERBYK)184 (manufactured by BYK Chemie Japan) may be added.

Further, the dispersibility can be maintained by adjusting the pH with a buffer such as boric acid or phosphoric acid, an acid such as hydrochloric acid or sulfuric acid, or a base such as sodium hydroxide or potassium hydroxide.

The resin-platinum complex 100 having the above-described configuration can be preferably used as a labeling substance in an immunoassay method such as EIA, RIA, CLIA, FIA, LIA, PA, ICA, HA, HI, etc., particularly by adsorbing an antigen or an antibody to the surface of the platinum particles 20. In particular, it is preferably used as a material for a labeling substance for immunological assay or a reagent for immunological assay, which is excellent in the visual judgment in a low concentration region (high sensitivity region). The form of the labeling substance for immunological measurement or the reagent for immunological measurement is not particularly limited, and for example, the labeling substance or the reagent for immunological measurement may be used in the form of a dispersion liquid in which the resin-platinum complex 100 is dispersed in water or a buffer solution having an adjusted pH.

The method for adsorbing the antigen or antibody to the surface of the platinum particle 20 is not particularly limited, and known physical adsorption and chemical adsorption methods can be used. Examples thereof include: immersing the resin-platinum complex 100 in a buffer solution containing an antigen or an antibody, and performing physical adsorption such as culture (incubate); or by introducing SH groups into the antigen or antibody and reacting the SH groups with the resin-platinum complex 100 to form chemical adsorption such as Pt-SH bonds. Among them, chemisorption is preferable in terms of the binding strength between the platinum particles 20 and the antigen or the antibody.

Next, a method of measuring an analyte using the resin-platinum complex 100 as a labeling substance, a test strip for lateral flow chromatography, and an analyte detection/quantification kit will be described.

[ test strip for lateral flow type chromatography ]

First, a lateral flow type chromatography test strip (hereinafter, sometimes simply referred to as "test strip") according to an embodiment of the present invention will be described with reference to fig. 3. As described later, the test strip 200 may be preferably used in a method for measuring an analyte according to an embodiment of the present invention.

Test strip 200 includes membrane 110. The film 110 is provided with a sample addition unit 120, a determination unit 130, and a liquid suction unit 140 in this order in the developing direction of the sample.

< film >

The membrane 110 used in the test strip 200 can be used as a membrane material in a general test strip. The thin film 110 exhibits, for example, capillary action and is formed of an inactive substance (a substance that does not react with the analyte 160, various ligands, and the like) containing a fine porous substance that allows the sample to spread while the sample is added. Specific examples of the film 110 include: fibrous or non-woven fibrous substrates (matrix) comprising polyurethane, polyester, polyethylene, polyvinyl chloride, polyvinylidene fluoride, nylon, cellulose derivatives and the like, films, filter papers, glass fiber filter papers, cloths, cotton and the like. Among these, a membrane containing a cellulose derivative or nylon, a filter paper, a glass fiber filter paper, or the like is preferably used, and a nitrocellulose membrane, a mixed nitrocellulose ester (mixture of nitrocellulose and cellulose acetate) membrane, a nylon membrane, or a filter paper is more preferably used.

to facilitate handling, test strip 200 preferably includes a support that supports membrane 110. The support may be made of plastic, for example.

< sample addition part >

Test strip 200 may also have a sample addition portion 120 for adding a sample containing analyte 160. Sample addition portion 120 is a portion for receiving a sample containing analyte 160 in test strip 200. The sample addition unit 120 may be formed on the film 110 on the upstream side of the determination unit 130 in the direction in which the sample is developed, or the sample addition unit 120 may be formed by providing a sample addition pad made of a material such as cellulose filter paper, glass fiber, polyurethane, polyacetate, cellulose acetate, nylon, or cotton cloth on the film 110.

< determination part >

In the determination section 130, a capture ligand 131 that specifically binds to the analyte 160 is immobilized. The capture ligand 131 is not particularly limited as long as it forms a specific binding with the analyte 160, and for example, an antibody or the like to the analyte 160 can be preferably used. The capture ligand 131 is immobilized so as not to move from the determination unit 130 even when the sample is supplied to the test strip 200. The capture ligand 131 may be directly or indirectly immobilized on the thin film 110 by physical binding or adsorption, or chemical binding or adsorption.

The determination unit 130 is not particularly limited as long as the complex 170 containing the labeled antibody 150 and the analyte 160 is in contact with the capture ligand 131 that specifically binds to the analyte 160. For example, the capture ligand 131 may be immobilized directly on the film 110, or the capture ligand 131 may be immobilized on a pad comprising cellulose filter paper, glass fiber, nonwoven fabric, or the like, which is immobilized on the film 110.

< liquid absorption part >

The liquid-absorbing part 140 is formed of a pad of a water-absorbing material such as cellulose filter paper, nonwoven fabric, cloth, or cellulose acetate. The moving speed of the sample after the front line (front line) of the added sample reaches the liquid absorbing section 140 differs depending on the material, size, and the like of the liquid absorbing section 140. Therefore, the optimum speed for detecting and quantifying the analyte 160 can be set by selecting the material, size, and the like of the liquid-absorbing portion 140. The liquid absorbing section 140 may have any configuration and may be omitted.

Test strip 200 may further include any part such as a reaction part and a control part, if necessary.

< reaction part >

Although not shown, in test strip 200, a reaction portion containing labeled antibody 150 may be formed on membrane 110. The reaction portion may be provided upstream of the determination portion 130 in the direction in which the sample flows. The sample addition part 120 in FIG. 3 may be used as a reaction part. When the test strip 200 has a reaction portion, if a sample containing the analyte 160 is supplied to the reaction portion or the sample addition portion 120, the analyte 160 contained in the sample can be brought into contact with the labeled antibody 150 in the reaction portion. In this case, since the complex 170 containing the analyte 160 and the labeled antibody 150 can be formed by simply supplying the sample to the reaction part or the sample addition part 120, the immunochromatography of the so-called one-step (one-step) type can be performed.

The reaction part is not particularly limited as long as it contains the labeled antibody 150 that specifically binds to the analyte 160, and may be formed by directly applying the labeled antibody 150 to the film 110. Alternatively, the reaction part may be formed by fixing an article in which a pad (composite pad) containing cellulose filter paper, glass fiber, nonwoven fabric, or the like, and the labeled antibody 150 are impregnated in the pad, to the film 110.

< control part >

Although not shown, test strip 200 may be provided with a control unit for immobilizing a capture ligand specifically binding to labeled antibody 150 on membrane 110 in the direction of sample development. The control unit also measures the color intensity together with the determination unit 130, and thus it can be confirmed that the sample supplied to the test strip 200 is spread and reaches the reaction unit and the determination unit 130, and the test is normally performed. The control unit may be manufactured in the same manner as the determination unit 130 and may have the same configuration, except that a different type of capture ligand that specifically binds to the labeled antibody 150 is used instead of the capture ligand 131.

[ method of measuring analyte ]

next, a method of measuring analyte 160 according to an embodiment of the present invention using test strip 200 will be described.

The method for measuring the analyte 160 according to the present embodiment is a method for measuring the analyte 160 by detecting or quantifying the analyte 160 contained in the sample. The method for measuring an analyte 160 according to the present embodiment uses a test strip 200, and the test strip 200 includes a membrane 110 and a determination section 130 in which a capture ligand 131 specifically binding to the analyte 160 is immobilized on the membrane 110. The method for measuring the analyte 160 according to the present embodiment may include the following steps (I) to (III);

Step (I): a step of bringing the analyte 160 contained in the sample into contact with a labeled antibody 150, wherein the labeled antibody 150 is an antibody that specifically binds to the analyte 160 and is labeled with a resin-platinum complex 100 having a structure in which a plurality of platinum particles 20 are immobilized on resin particles 10;

Step (II): a step of bringing the complex 170 containing the analyte 160 and the labeled antibody 150 formed in step (I) into contact with the capture ligand 131 in the determination section 130;

Step (III): and a step of measuring the localized surface plasmon resonance of the resin-platinum composite 100 and the color development intensity derived from the absorption of optical energy by electron transfer.

Step (I):

Step (I) is a step of bringing the analyte 160 contained in the sample into contact with the labeled antibody 150. The form of contact is not particularly limited as long as a complex 170 containing the analyte 160 and the labeled antibody 150 is formed. For example, the sample may be supplied to the sample adding portion 120 or a reaction portion (not shown) of the test strip 200, and the analyte 160 may be brought into contact with the labeled antibody 150 in the reaction portion, or the analyte 160 in the sample may be brought into contact with the labeled antibody 150 before the sample is supplied to the test strip 200.

The complex 170 formed in step (I) spreads on the test strip 200 and moves to reach the determination unit 130.

Step (II):

In step (II), in the determination section 130 of the test strip 200, the complex 170 containing the analyte 160 and the labeled antibody 150 formed in step (I) is brought into contact with the capture ligand 131. When complex 170 is contacted with capture ligand 131, capture ligand 131 specifically binds to analyte 160 of complex 170. As a result, the complex 170 is captured by the determination unit 130.

Since the capture ligand 131 does not specifically bind to the labeled antibody 150, when the labeled antibody 150 not bound to the analyte 160 reaches the determination section 130, the labeled antibody 150 not bound to the analyte 160 passes through the determination section 130. Here, when a control unit (not shown) to which another capture ligand that specifically binds to the labeled antibody 150 is immobilized is formed in the test strip 200, the labeled antibody 150 passing through the determination unit 130 continues to spread and binds to the other capture ligand in the control unit. As a result, the labeled antibody 150 that has not formed a complex 170 with the analyte 160 is captured in the control unit.

after step (II), if necessary, a washing step of washing the test strip 200 with a buffer commonly used in biochemical tests such as water, physiological saline, phosphate buffer, and the like may be performed before step (III). The labeled antibody 150 that has not been captured in the determination section 130 or the determination section 130 and the control section (the labeled antibody 150 that has not bound to the analyte 160 and has not formed the complex 170) can be removed in accordance with the washing step.

By performing the washing step, in the step (III), when the localized surface plasmon resonance of the determination unit 130, or the resin-platinum complex 100 in the determination unit 130 and the control unit, and the color development derived from the absorption of light energy by electron transfer are measured, the color development intensity of the background (background) can be reduced, the signal/background ratio can be improved, and the detection sensitivity and the quantitative determination can be further improved.

Step (III):

The step (III) is a step of measuring the localized surface plasmon resonance of the resin-platinum composite 100 and the color development intensity derived from the absorption of light energy by electron transfer. After the step (II) or the washing step as necessary, the localized surface plasmon resonance of the resin-platinum complex 100 and the color intensity derived from the absorption of light energy by electron transfer are measured in the test strip 200.

When the control portion is formed in the test strip 200, the labeled antibody 150 is captured by another capture ligand in the control portion to form a complex in step (II). Therefore, in step (III), in test strip 200, localized surface plasmon resonance and color development resulting from absorption of light energy by electron transfer may occur not only in determination unit 130 but also in the control unit. In this manner, the control unit together with the determination unit 130 measures the color intensity, and thereby it is possible to confirm whether or not the sample supplied to the test strip 200 has spread normally and reached the reaction unit and the determination unit 130.

< sample and analyte >

the sample in the method for measuring an analyte according to the present embodiment is not particularly limited as long as it contains a substance that can be an antigen, such as a protein, as the analyte 160. Examples of the sample include a biological sample (i.e., whole blood, serum, plasma, urine, saliva, sputum, nasal or throat swab, cerebrospinal fluid, amniotic fluid, nipple secretion, tears, sweat, skin exudate, tissue or cell, and an extract from feces) or a food extract containing the target analyte 160. If necessary, the analyte 160 contained in the sample may be pretreated before the step (I) in order to easily cause a specific binding reaction between the labeled antibody 150 and the capture ligand 131 and the analyte 160. Here, examples of the pretreatment include: chemical treatment using various chemicals such as acids, alkalis, and surfactants, or physical treatment using heat, stirring, or ultrasonic waves. In particular, when the analyte 160 is a substance that is not normally exposed on the surface, such as an influenza virus Nucleoprotein (NP) antigen, it is preferable to perform a treatment with a surfactant or the like. A nonionic surfactant may be used as the surfactant for the purpose in consideration of the binding reactivity between the capture ligand 131 and the analyte 160 in a specific binding reaction, for example, an antigen-antibody reaction or the like.

The sample may be diluted with a solvent (water, physiological saline, buffer solution, or the like) or a water-mixed organic solvent used in a general immunological analysis method.

Examples of the analyte 160 include: the tumor marker, the signal transduction substance, and proteins (including polypeptides, oligopeptides, etc.) such as hormones, nucleic acids (including single-or double-stranded Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), polynucleotides, oligonucleotides, Peptide Nucleic Acids (PNA), etc.) or other molecules having nucleic acids, sugars (including oligosaccharides, polysaccharides, sugar chains, etc.) or substances having sugar chains, lipids, etc., are not particularly limited as long as they specifically bind to the labeled antibody 150 and the capture ligand 131, and examples thereof include: Carcino-Embryonic Antigen (CEA), Human epidermal growth factor receptor 2 (HER 2) Protein, Prostate Specific Antigen (PSA), Carbohydrate Antigen 19-9(Carbohydrate Antigen 19-9, CA19-9), alpha-fetoprotein (alpha-fetoprotein, AFP), Immunosuppressive Acidic Protein (Immunosuppressive Acidic Protein, IAP), Cancer Antigen 15-3(Cancer Antigen 15-3, CA15-3), Cancer Antigen 125(Cancer Antigen 125, CA125), estrogen receptor (estrogen receptor), progesterone receptor (progesterone receptor), occult blood (blood), troponin I, troponin T, Creatine Kinase (Human MB-C-Reactive Protein, CRP), HCG), Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), syphilis antibodies, influenza virus human hemoglobin (inflenza hemoglobin), Chlamydia (Chlamydia) antigens, group a beta hemolytic streptococcus antigens, Hepatitis B Surface (HBs) antibodies, HBs antigens, rotaviruses (rotaviruses), adenoviruses (adenoviruses), Albumin (Albumin), glycated Albumin, and the like. Among these, the antigen solubilized by the nonionic surfactant is preferable, and the antigen formed from an aggregate such as a viral nucleoprotein is more preferable.

< labeled antibody >

The labeled antibody 150 is used to contact the analyte 160 contained in the sample in step (I) to form a complex 170 containing the analyte 160 and the labeled antibody 150. The labeled antibody 150 is obtained by labeling an antibody that specifically binds to the analyte 160 with the resin-platinum complex 100 having a structure in which a plurality of platinum particles 20 are immobilized on the resin particles 10. The term "labeling" as used herein means that the resin-platinum complex 100 is directly or indirectly immobilized on the antibody by chemical binding, adsorption, physical binding, adsorption or the like, to such an extent that the resin-platinum complex 100 is not detached from the labeled antibody 150 in the steps (I) to (III). For example, the labeled antibody 150 may be formed by directly binding the resin-platinum complex 100 to the antibody, or may be formed by binding the antibody to the resin-platinum complex 100 via an arbitrary linker molecule, or may be formed by separately fixing the antibody to insoluble particles.

In the present embodiment, the "antibody" is not particularly limited, and for example, antibody fragments having an ability to bind to an antigen [ for example, H chain, L chain, Fab, F (ab')2, and the like ] may be used in addition to polyclonal antibodies (polyclonal antibodies), monoclonal antibodies (monoclonal antibodies), and antibodies obtained by gene recombination. The Immunoglobulin may be any of Immunoglobulin G (IgG), IgM, IgA, IgE, and IgD. The species of the antibody-producing animal may be a human species, or an animal other than a human (e.g., mouse, rat, rabbit, goat, horse, etc.). Specific examples of the antibody include: anti-PSA antibodies, anti-AFP antibodies, anti-CEA antibodies, anti-adenovirus antibodies, anti-influenza virus antibodies, anti-HCV antibodies, anti-IgG antibodies, anti-human IgE antibodies, and the like.

< preferred method for producing labeled antibody >

Next, a preferred method for producing the labeled antibody 150 will be described. The production of the labeled antibody 150 may include at least the following step a;

Step A) a step of mixing and binding the resin-platinum complex 100 with an antibody under a first pH condition, thereby obtaining a labeled antibody 150,

Preferably further comprising step B;

Step B) a step of treating the labeled antibody 150 under a second pH condition.

[ step A ]

In step a, the resin-platinum complex 100 is mixed with an antibody under a first pH condition to obtain a labeled antibody 150. In step a, the solid resin-platinum complex 100 is preferably brought into contact with the antibody in a state of being dispersed in a liquid phase.

The first pH condition is preferably a condition within a range of pH 2 to 10, and more preferably within a range of pH 5 to 9, for example, from the viewpoint of uniformly contacting the resin-platinum complex 100 and the antibody while maintaining the dispersion of the resin-platinum complex 100 and the activity of the antibody. With respect to the conditions for binding the resin-platinum complex 100 to the antibody, if the pH is less than 2, the antibody may be deteriorated and inactivated by strong acidity, and if the pH exceeds 10, the resin-platinum complex 100 is aggregated and dispersed when mixed with the antibody, which may be difficult. However, in the case where the antibody is not inactivated by strong acidity, the treatment may be performed under a condition of pH less than 2.

Step a is preferably performed in a Binding Buffer (Binding Buffer) adjusted to the first pH condition. For example, a predetermined amount of the resin-platinum complex 100 is mixed with a binding buffer adjusted to the pH value, and the mixture is thoroughly mixed. For example, a boric acid solution adjusted to a predetermined concentration can be used as the binding buffer. The pH of the binding buffer can be adjusted using, for example, hydrochloric acid, sodium hydroxide, or the like.

Then, a predetermined amount of antibody is added to the resulting mixture, and the mixture is sufficiently stirred and mixed to obtain a solution containing a labeled antibody. The thus obtained labeled antibody-containing solution can be separated as a solid portion only from the labeled antibody 150 by a solid-liquid separation method such as centrifugation.

[ step B ]

In step B, blocking (blocking) for suppressing non-specific adsorption of the labeled antibody 150 is performed by treating the labeled antibody 150 obtained in step a under a second pH condition. In this case, the labeled antibody 150 separated by the solid-liquid separation method is dispersed in the liquid phase under the second pH condition.

The second pH condition is, for example, preferably within a range of pH 2 to 10 from the viewpoint of maintaining the activity of the antibody and suppressing aggregation of the labeled antibody 150, and more preferably within a range of pH 5 to 9 from the viewpoint of suppressing non-specific adsorption of the labeled antibody 150. Under the blocking conditions, the antibody may be deteriorated and inactivated by strong acidity when the pH is less than 2, and when the pH exceeds 10, the labeled antibody 150 may aggregate and become difficult to disperse.

Step B is preferably performed using a Blocking Buffer (Blocking Buffer) adjusted to the second pH condition. For example, a blocking buffer adjusted to the above pH value is added to a predetermined amount of the labeled antibody 150, and the labeled antibody 150 is uniformly dispersed in the blocking buffer. The blocking buffer is preferably a solution using a protein that does not bind to the analyte, for example. Examples of proteins that can be used in the blocking buffer include bovine serum albumin, protein albumin, casein, and gelatin. More specifically, it is preferable to use a bovine serum albumin solution or the like adjusted to a predetermined concentration. The pH of the blocking buffer can be adjusted using, for example, hydrochloric acid, sodium hydroxide, or the like. For dispersing the labeled antibody 150, a dispersing method such as ultrasonic treatment is preferably used. Thus, a dispersion in which the labeled antibody 150 is uniformly dispersed can be obtained.

In the above-described steps a and B, the resin-platinum composite 100 having the platinum particles 20 is less likely to undergo aggregation due to pH, and can be treated at a pH in a wide range from acidic to alkaline. On the other hand, for example, in the case of a resin-gold complex having gold particles, the resin-gold complex tends to aggregate together at a pH exceeding 7 in step a, and the resin-gold complex tends to aggregate together at a pH exceeding 9 in step B. Therefore, the resin-platinum complex 100 used in the present invention also has an advantage that it is not easily limited by the conditions for producing the labeled antibody.

As described above, a dispersion of the labeled antibody 150 can be obtained. For example, only the labeled antibody 150 can be separated from the dispersion as a solid portion by a solid-liquid separation method such as centrifugation. Further, a cleaning treatment, a preservation treatment, and the like may be performed as necessary. The cleaning and storage processes will be described below.

(cleaning treatment)

The washing treatment is performed by adding a washing buffer to the labeled antibody 150 separated by the solid-liquid separation method and uniformly dispersing the labeled antibody 150 in the washing buffer. In the dispersion, for example, a dispersion method such as ultrasonic treatment is preferably used. The washing buffer is not particularly limited, and Tris (hydroxymethyl) aminomethane (Tris) buffer, glycinamide buffer, arginine buffer, or the like can be used at a predetermined concentration adjusted to a pH value within the range of 8 to 9. The pH of the washing buffer can be adjusted using, for example, hydrochloric acid, sodium hydroxide, or the like. The washing treatment of the labeled antibody 150 may be repeated as many times as necessary.

(preservation treatment)

The storage treatment is to add a storage buffer to the labeled antibody 150 separated by the solid-liquid separation method and uniformly disperse the labeled antibody 150 in the storage buffer. In the dispersion, for example, a dispersion method such as ultrasonic treatment is preferably used. The storage buffer may be, for example, a solution obtained by adding an anti-agglomeration agent and/or a stabilizer at a predetermined concentration to a washing buffer. Examples of the anti-agglomerating agent include sugars such as sucrose, maltose, lactose and trehalose, and polyols such as glycerin and polyvinyl alcohol. The stabilizer is not particularly limited, and for example, proteins such as bovine serum albumin, protein albumin, casein, and gelatin can be used. In this manner, the labeled antibody 150 can be preserved.

In each of the above steps, a surfactant, or a preservative such as sodium azide or paraben may be further used as necessary.

[ kit for measuring analyte ]

the kit for measuring an analyte according to an embodiment of the present invention is, for example, a kit for detecting or quantifying the analyte 160 contained in a sample by using the test strip 200 according to the method for measuring an analyte according to the embodiment.

The analyte measurement kit of the present embodiment includes:

Test strip 200, comprising membrane 110, and

A determination unit 130 in which a capture ligand 131 specifically binding to the analyte 160 is immobilized on the film 110; and

The detection reagent contains a labeled antibody 150, and the labeled antibody 150 is an antibody that specifically binds to the analyte 160 and is labeled with a resin-platinum complex 100 having a structure in which a plurality of platinum particles 20 are immobilized on resin particles 10.

The analyte measurement kit of the present embodiment may further include other components as necessary.

In the case of using the kit for measuring an analyte according to the present embodiment, after the step (I) is performed by bringing the labeled antibody 150 in the detection reagent into contact with the analyte 160 in the sample, the step (II) and the step (III) may be performed in this order by supplying the sample to the reaction part or the sample addition part 120 of the test strip 200. Alternatively, after the detection reagent is applied to the upstream side of the determination section 130 of the test strip 200 and dried appropriately to form the reaction section, the sample may be added to the formed reaction section or a position upstream of the reaction section (for example, the sample addition section 120), and steps (I) to (III) may be performed in this order.