JP2014209117A - Color particles for immunochromato, and immunochromato reagent for diagnosis using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide color particles for immunochromato where a composition forming a surface expresses colorability, and which can exhibit a dark color tone while maintaining the surface composition of a latex particle, and to provide an immunochromato reagent for diagnosis using the color particles.SOLUTION: Color particles for immunochromato contain a high polymer containing a π-conjugated compound as a component consisting a surface. For example, the color particles for the immunochromato comprise the coated high polymer containing the π-conjugated compound on a surface of a hydrocarbon based fine particle.

Description

  The present invention relates to an immunochromatographic colored particle suitably used for a diagnostic immunochromatographic reagent, and a diagnostic immunochromatographic reagent using the colored particle.

  Conventionally, for the purpose of diagnosing various diseases, a diagnostic immunochromatographic reagent for detecting a test substance by visual judgment by combining a substance that immunologically binds to the test substance and a chromatography principle has been widely used. . The immunochromatographic reagent for diagnosis can be bound to the above test substance by immobilizing an antibody (or antigen) against the test substance antigen (or antibody) on a chromatographic medium and creating an immune reaction site as a stationary phase. Of an immunochromatograph using a detection carrier sensitized by a specific antibody (or antigen) and a specimen containing a test substance to form an antigen-antibody complex and using the liquid containing them as a mobile phase Used in measurement methods.

  In the measurement method, a specimen containing a test substance in contact with a detection carrier undergoes an immune reaction, and the detection particles—the antibody used for sensitization (or the antigen used for sensitization) —in the specimen A complex consisting of an antigen (or antibody) is produced. When this complex reaches the reaction site on the chromatograph, an immune reaction is performed again, the complex is bound to the immobilized antibody (or immobilized antigen), and the detection carrier is captured. The presence or absence of the test substance in the sample can be determined by visually determining the presence or absence of this (the measurement method is referred to as an immunochromatography method).

  In the immunochromatography method, fine particles colored on a detection carrier are widely used to facilitate visual determination. As such a detection carrier, colloidal particles such as colloidal metal particles or colloidal metal oxide particles that naturally color depending on the particle size or preparation conditions, or latex particles made of a synthetic polymer are colored. Colored latex particles obtained by polymerizing monomers together with the obtained colored latex particles and colorants are used. However, since the color tone of the colloidal particles is determined depending on the particle size and the preparation conditions, there are problems such that it is impossible to prepare a desired color and it is difficult to obtain a clear dark color tone. On the other hand, colored latex particles are advantageous in that the color tone can be freely selected, but there are problems such as increasing the amount of coloration, that is, it is difficult to obtain a dark color tone, and visual judgment is difficult when used in immunochromatography. was there.

  In order to solve this problem, Patent Document 1 discloses a method in which the content of the colorant in the colored latex particles is 10% by weight or more, and the visual judgment is improved. However, even with this method, it can not be said that sufficient sensitivity is still secured, and when the amount of coloring is further increased, the pigment and the like come to cover the surface of the latex particles, resulting in damage to the original surface state of the particles, It has been a problem to cause clogging due to non-specific reaction or excessive aggregation.

JP 2003-202344 A

Therefore, it is hoped that the detection carrier that does not cause clogging due to non-specific reaction or overaggregation, that is, the detection carrier is darkened and the surface state of the latex particles is maintained while further improving visual judgment. It was rare.
The present invention has been made in view of the above circumstances, and the colored particles for immunochromatography capable of exhibiting a dark color tone while maintaining the surface composition of the latex particles while the surface forming composition itself exhibits colorability, It is an object of the present invention to provide a diagnostic immunochromatographic reagent using colored particles.

The present invention relates to the following.
<Invention 1>
A colored particle for immunochromatography, comprising a polymer containing a π-conjugated compound as a component constituting the surface.
<Invention 2>
The colored particles for immunochromatography according to invention 1, wherein the colored particles have an average particle size of 50 to 1000 nm.
<Invention 3>
The colored particles for immunochromatography according to invention 1 or 2, wherein the surface of the hydrocarbon fine particles is coated with a polymer containing a π-conjugated compound.
<Invention 4>
The coloring for immunochromatography according to any one of inventions 1 to 3, wherein the polymer containing a π-conjugated compound is at least one selected from the group consisting of polyacetylene, polyaniline, polyfuran, polypyrrole, and polythiophene. particle.
<Invention 5>
Hydrocarbon fine particles
(1) one or more polymerizable monomers selected from the group consisting of a polymerizable monomer having a phenyl group, a polymerizable monomer having a methacryloyl group, and a polymerizable monomer having an acryloyl group;
(2) The colored particles for immunochromatography according to invention 3 or 4, wherein a polymerizable monomer having a phenyl group and a sulfonate is copolymerized.
<Invention 6>
The invention according to any one of inventions 3 to 5, wherein a polymerizable monomer having a sulfonate salt is present when the surface of the hydrocarbon fine particles is coated with a polymer containing a π-conjugated compound. Colored particles for immunochromatography.
<Invention 7>
The colored particles for immunochromatography according to any one of inventions 1 to 6, wherein the colored particles are black particles.
<Invention 8>
A diagnostic immunochromatographic reagent using the colored particles for immunochromatography according to any one of inventions 1 to 7.
<Invention 9>
An immunochromatographic measurement method using the immunochromatographic reagent according to invention 8.

  According to the present invention, colored particles for immunochromatography that can maintain the surface composition of latex particles and can exhibit a deep color tone are obtained because the composition itself that forms the particle surface exhibits colorability. It is possible to provide immunochromatographic colored particles with excellent visibility that can be converted to a large amount, and diagnostic immunochromatographic reagents using the colored particles.

Hereinafter, the colored particles for immunochromatography of the present invention will be described in detail.
The colored particles for immunochromatography of the present invention are colored particles containing a polymer containing a π-conjugated compound as a component constituting the surface. Among these, colored particles are obtained by coating the surface of hydrocarbon-based fine particles with a polymer containing a π-conjugated compound. These are suitably used as detection carriers for immunochromatography.

The hydrocarbon fine particles are
(1) one or more polymerizable monomers selected from the group consisting of a polymerizable monomer having a phenyl group, a polymerizable monomer having a methacryloyl group, and a polymerizable monomer having an acryloyl group;
(2) There is no particular limitation as long as it is a particle obtained by copolymerizing a polymerizable monomer having a phenyl group and a sulfonate, and particles conventionally used in the field of immunoassay can be used.

  Examples of the polymerizable monomer having a phenyl group include polymerizable unsaturated aromatics such as styrene, chlorostyrene, α-methylstyrene, and vinyltoluene. Further, a crosslinkable monomer such as divinylbenzene is also included, and an appropriate amount may be present. Examples of the polymerizable monomer having a methacryloyl group or an acryloyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. Polymerizable unsaturated carboxylic acid esters such as glycidyl (meth) acrylate, polymerizable unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, maleic acid and fumaric acid, and salts thereof such as (meta ) Polymerizable unsaturated carboxylic acid amides such as sodium acrylate, potassium (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylate and the like. Moreover, crosslinkable monomers, such as ethylene glycol (meth) acrylate, propylene glycol (meth) acrylate, and methylene bis (meth) acrylamide, are also included, and an appropriate amount may be present. These monomers can be used alone or in combination of two or more.

  Examples of the polymerizable monomer having a phenyl group and a sulfonate include sodium styrenesulfonate, potassium styrenesulfonate, lithium styrenesulfonate, and the like.

  Among these, a copolymer composed of styrene and sodium styrenesulfonate, and a copolymer composed of styrene, methyl methacrylate and sodium styrenesulfonate are particularly preferable.

  As the polymerization method of the copolymer, conventionally known polymerization methods can be used, and examples thereof include a dispersion polymerization method, a suspension polymerization method, an emulsion polymerization method, and a soap-free emulsion polymerization method. Is preferred. As the soap-free emulsion polymerization method, for example, a method described in JP-A No. 2003-51095 can be used.

  The present invention is characterized in that a polymer containing a π-conjugated compound is contained as a component constituting the surface. The hydrocarbon fine particles coated with the polymer containing the π-conjugated compound have been described above. However, the hydrocarbon fine particles do not exist, that is, the polymer fine particles containing the π-conjugated compound are made of a polymer containing the π-conjugated compound. Needless to say, the coated colored particles for immunochromatography are also included in the present invention.

  Further, the polymer containing the π-conjugated compound may be present as a main component in the components constituting the surface of the colored particles. When the surface includes a π-conjugated compound as a main component, the colored particles exhibit a black color and are preferably used as black colored particles. Here, the main component means a component that is 70% by mass or more of the whole. Examples of components other than the main component (π-conjugated compound) include black inorganic materials such as titanium black and iron oxide. For example, the surface of the colored particles for immunochromatography of the present invention, together with the π-conjugated compound, contains these black inorganic materials. May be formed from the composition which contains 30 mass% or less. In that case, these black inorganic materials may be allowed to coexist when a polymer containing a π-conjugated compound is synthesized by polymerization or polycondensation. In addition to the π-conjugated compound as the main component, the composition may contain a polymer other than the π-conjugated compound as long as it does not affect the black color of the black particles.

  A polymer containing a π-conjugated compound is a polymer produced using a monomer capable of forming a polymer containing a π-conjugated compound. Such a monomer (hereinafter referred to as π-conjugated-forming monomer) Examples of the body include acetylene, aniline, furan, pyrrole, thiophene, and derivatives thereof, and one or more of these can be used.

  Specific examples of the polymer containing a π-conjugated compound include polyacetylene obtained by polymerizing acetylene and derivatives thereof, polyaniline obtained by polymerizing aniline and derivatives thereof, polyfuran obtained by polymerizing furan and derivatives thereof, and pyrrole. And polypyrrole obtained by polymerizing thiophene and derivatives thereof, and polythiophene obtained by polymerizing derivatives thereof, among which polypyrrole is preferable.

  A polymer containing a π-conjugated compound can be produced by a known production method such as oxidative polymerization, electrolytic polymerization, radical polymerization, or coupling reaction of raw material monomers. In addition, during the production of the polymer, known initiators, additives for increasing the stability during polymerization, such as dispersion stabilizers such as polyacrylic acid, polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecyl sulfate, hexabromide Surfactants such as decyltrimethylammonium and polyoxyethylene lauryl ether can be appropriately used. By using these, an extremely thin film composed of these dispersion stabilizers, surfactants and the like may be formed on the outer side of the surface formed with the π-conjugated compound as a main component. It cannot be said that the thin film derived from such a manufacturing process substantially forms the particle surface. Therefore, the colored particles for immunochromatography of the present invention include those in which a thin film derived from such a production process is formed on the outermost surface as a result.

  The surface of the hydrocarbon fine particle was coated with a polymer containing a π-conjugated compound in the presence of a polymerizable monomer having a phenyl group and a sulfonate regardless of the presence or absence of the dispersion stabilizer and the surfactant. Colored particles for immunochromatography are also one aspect of the present invention.

  When the polymer containing the π-conjugated compound is polypyrrole, the surface of the colored particles for immunochromatography has a certain positive charge, but by allowing a polymerizable monomer having a phenyl group and a sulfonate to exist on the surface, It can be used as a colored particle having negative charge, and is preferably used for binding an antigen or antibody which is not positively charged. In addition, since a component having a phenyl group is present on the surface in a certain ratio, it is one of the features of the present invention that moderate hydrophobicity is imparted and an environment favorable for physical adsorption of antigens and antibodies can be provided. is there.

  The colored particles for immunochromatography of the present invention are particles having an average particle size of 50 to 1000 nm, preferably 100 to 500 nm. The CV value (particle size variation coefficient) is preferably 10% or less. The CV value is calculated by “standard deviation of particle size distribution ÷ average particle size × 100”. If the average particle diameter of the colored particles is less than 50 nm, the visibility is poor, and if it exceeds 1000 nm, the possibility of clogging in the membrane increases. In addition, the average particle diameter in this specification shows the average value of the value calculated | required by analyzing 100 or more particle | grain images in arbitrary three visual fields obtained with the transmission electron microscope using an image analyzer.

  The average particle size of the colored particles for immunochromatography of the present invention is, for example, controlled by a method using hydrocarbon fine particles having a constant particle size, controlled by a dispersion stabilizer during synthesis of colored particles, controlled by an emulsifier, controlled by particle charge, Although control by a known method such as control by microchannel diameter or control by stirring operation is possible, a method using hydrocarbon-based fine particles having a constant particle size is simple and preferable. The particle size control of the hydrocarbon-based fine particles may be controlled by the method described in JP-A No. 2003-51095, for example, by adjusting the amount of the polymerization initiator or changing the polymerization temperature. The method of adjusting is mentioned.

  A diagnostic immunochromatographic reagent using the colored particles for immunochromatography of the present invention as a detection carrier is also one aspect of the present invention. Examples of items used as diagnostic immunochromatography reagents include influenza virus, RS virus, adenovirus, rotavirus, norovirus and the like. Antibody-sensitized particles can be produced by binding antibodies corresponding to these items to the colored particles for immunochromatography of the present invention to obtain immunochromatographic reagents. The binding method is not particularly limited, and a conventionally known method can be used, for example, by immersing colored particles for immunochromatography in a buffer solution containing an antigen (or antibody) and incubating for a certain time at a certain temperature. Examples include a physical adsorption method.

  In addition, if the diagnostic immunochromatographic reagent of the present invention is used, for example, in a diagnostic test strip using the principle of immunochromatography, it is contained in a conjugate pad by impregnating antibody-sensitized particles in the liquid of the moving layer, The presence of the test substance in the specimen can be determined by binding and agglutinating with an antibody (or antigen) against the antigen (or antibody) which is the test substance immobilized as an immune reaction site on the membrane.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Preparation of hydrocarbon fine particles 1]
In a 2000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a reflux condenser, a temperature detector, and a nitrogen introduction tube, 1100 g of deionized water, 170 g of styrene (manufactured by Wako Pure Chemical Industries), and parastyrene sulfone After weighing 0.08 g of sodium acid (manufactured by Tokyo Chemical Industry) and 0.36 g of potassium persulfate (manufactured by Wako Pure Chemical Industries) as a polymerization initiator, 210 r. p. m. The inside of the container was purged with nitrogen while stirring, and polymerization was carried out at 70 ° C. for 18 hours.
The obtained white solution was filtered with a paper filter paper and purified by dialysis with a cellulose tube (dialysate: water, the number of purifications was 5 times or more) to obtain the desired hydrocarbon fine particles (referred to as fine particles 1). When the particle size of the obtained fine particles was measured with a transmission electron microscope, it was 301 nm (CV 6.0%).

[Preparation of hydrocarbon fine particles 2]
The target hydrocarbon fine particles are the same as the hydrocarbon fine particles 1 except that 170 g of styrene is a mixture of 100 g of styrene and 70 g of methyl methacrylate, and 0.05 g of sodium parastyrene sulfonate is used. (Referred to as fine particles 2). When the particle diameter was measured in the same manner as described above, the particle diameter of the obtained fine particles was 235 nm (CV 5.3%).

<Example 1>
In a 2000 mL separable flask equipped with a four-neck separable cover, stirring blade, reflux condenser, temperature detector, and nitrogen inlet tube, 700 g of deionized water, 10 g of the above-mentioned fine particles 1, and sodium parastyrenesulfonate After weighing 20 g (manufactured by Tokyo Chemical Industry) and 10 g of pyrrole (manufactured by Wako Pure Chemical Industries), 210 r. p. m. The inside of the container was purged with nitrogen while stirring, and the temperature was raised to 60 ° C.
Subsequently, 34.0 g of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was dissolved in 300 g of deionized and dropped into the mixed solution. After completion of the dropwise addition, the mixture was further heated and stirred for 8 hours, and then cooled to stop the reaction.
Centrifugation was performed, moderate deionized water was added, and the mixture was redispersed with an ultrasonic cleaner. This operation was repeated three times to obtain black colored particles 1 (colored particles 1 made of polypyrrole). It was 368 nm (CV6.4%) when the particle size of the particle | grains obtained with the transmission electron microscope was measured.

<Example 2>
Black coloration in the same manner as for the production of colored particles 1 with polypyrrole, except that the amount of sodium parastyrenesulfonate used was changed to 10 g, the amount of pyrrole to 5 g, and the amount of ammonium persulfate to 17.0 g. Particles were obtained (colored particles 2 with polypyrrole). It was 342 nm (CV6.3%) when the particle size of the obtained particle | grains was measured similarly to the above.

<Example 3>
Black colored particles were obtained in the same manner as in the production method of the colored particles 1 made of polypyrrole except that the fine particles 1 were changed to the fine particles 2 (colored particles 3 made of polypyrrole). It was 295 nm (CV 5.6%) when the particle size of the obtained particle was measured in the same manner as described above.

<Example 4>
In a 2000 mL separable flask equipped with a four-necked separable cover, a stirring blade, a reflux condenser, a temperature detector, and a nitrogen inlet tube, 700 g of deionized water, 10 g of the above-described fine particles 1, polyvinyl pyrrolidone (K30, After weighing 10 g of Wako Pure Chemical) and 10 g of pyrrole (Wako Pure Chemical), 210 r. p. m. The inside of the container was purged with nitrogen while stirring, and the temperature was raised to 60 ° C.
Subsequently, 34.0 g of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was dissolved in 300 g of deionized and dropped into the mixed solution. After completion of the dropwise addition, the mixture was further heated and stirred for 8 hours, and then cooled to stop the reaction.
Centrifugation was performed, moderate deionized water was added, and the mixture was redispersed with an ultrasonic cleaner. This operation was repeated three times to obtain black colored particles 4 (colored particles 4 made of polypyrrole). It was 335 nm (CV6.3%) when the particle size of the particle | grains obtained with the transmission electron microscope was measured.

<Example 5>
Black colored particles were obtained in the same manner as the colored particle 4 production method except that the amount of pyrrole used was changed to 5 g and the amount of ammonium persulfate was changed to 17.0 g (colored particles 5 made of polypyrrole). . It was 323 nm (CV6.2%) when the particle size of the obtained particle | grains was measured similarly to the above.

<Example 6>
Black colored particles were obtained in the same manner as the colored particles 4 made of polypyrrole except that the fine particles 1 were changed to the fine particles 2 (colored particles 6 made of polypyrrole). When the particle size of the obtained particles was measured in the same manner as described above, it was 265 nm (CV 5.5%).

<Comparative Example 1>
[Preparation of colored particles from commercially available dyes 1]
According to Example 1 described in JP-A-2003-202344, colored particles were produced as follows.
Centrifugation of a white solution of fine particles 1 obtained by dissolving a dye solution in which 2.4 g of oil-soluble dye oil blue (manufactured by Orient Chemical Co., Ltd.) in 2000 mL of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) to a solid amount of 6 g At 12000 rpm, the supernatant was added to the waste, and the mixture was heated and stirred at 45 ° C. for 3 days (in this case, methanol was gradually evaporated). Centrifugation was then performed, methanol was discarded, moderate deionized water was added, and redispersed with an ultrasonic cleaner. This operation was repeated three times to obtain blue colored particles in which methanol was completely replaced with deionized water (colored particles 1 with a commercially available dye). When the particle size was measured with a transmission electron microscope, it was 325 nm (CV 6.8%).

<Comparative example 2>
[Preparation of colored particles using commercially available dyes 2]
Blue colored particles were obtained in the same manner as the production method of the colored particles 1 with a commercially available dye except that the fine particles 1 were changed to the fine particles 2 (colored particles 2 with a commercially available dye). Similarly, the particle diameter was measured and found to be 254 nm (CV 5.9%).

[Application example]
<Preparation of immunochromatographic reagent for influenza virus measurement>
1. Preparation of colored particle-labeled anti-influenza A virus antibody (1) 20 mM MES containing 2.5 mg / mL anti-influenza A virus monoclonal antibody in 5 mL of 20 mM MES (pH 6.5) buffer containing 2 wt% colored particles (pH 6. 5) 5 mL of buffer solution was added and stirred at room temperature for 2 hours. Then, centrifuged at 13,000 rpm for 10 minutes, after removing the supernatant, 10 mL of 2% bovine serum albumin (BSA) aqueous solution containing 10% sucrose was added, and further stirred for 2 hours, then centrifuged at 13,000 rpm for 10 minutes, Antibody-sensitized colored particles were obtained. Thereafter, 10 mL of 2% BSA aqueous solution containing 10% sucrose was further added to obtain about 1.0 wt% colored particle-labeled anti-influenza A virus antibody (conjugate).

2. Preparation of conjugate coating pad The conjugate prepared in 1 above was mixed with Tris buffer (pH 8.5) containing 0.5% casein and 10% sucrose so that the conjugate was 6.4 OD (λ650 nm) / mL. Produced. Next, the conjugate solution was soaked at 10 μl / cm into a glass fiber pad (manufactured by Lydall) using a dispenser “XYZ3050” (manufactured by BIO DOT) for immunochromatography. Then, it was heated and dried in a dry oven at 70 ° C. for 30 minutes to obtain a conjugate coating pad.

3. Preparation of anti-influenza virus antibody-immobilized membrane A nitrocellulose membrane (manufactured by Sartorius), an anti-influenza A virus antibody having an epitope different from that of the colored particle-labeled anti-influenza A virus antibody prepared at 0.75 mg / mL and A 10 mM phosphate buffer (pH 7.2) containing 2.5% sucrose was applied in a line having a width of about 1 mm. For application, a dispenser “XYZ3050” (manufactured by BIO DOT) for immunochromatography was used, and the discharge amount was set to 1 uL / cm. The nitrocellulose film after the line coating was dried in a dry oven at 70 ° C. for 45 minutes to obtain an anti-influenza virus antibody-immobilized film.

4). Preparation of test strip The anti-influenza virus antibody-immobilized membrane is attached to a plastic pressure-sensitive adhesive sheet, and 2. The conjugate application pad prepared in 1 was placed and mounted, and an absorbent pad (Whatman, 740-E) was placed and mounted on the opposite end. Finally, a polyester film was placed on the upper surface so as to cover the antibody-immobilized membrane and the absorption pad, and laminated. In this way, the structure in which the respective constituent elements were overlapped was cut to a width of 4 mm to prepare a test strip. The dimensions of the test strip were 4 mm × 98 mm (width × length) and were in the form of an immunochromatographic test strip.

5. Preparation of sample extract and sensitivity confirmation sample
The specimen extract was 50 mM Tris buffer (pH 8.5) containing 200 mM potassium chloride, 150 mM L-arginine, 0.5% Brij35, 0.25% BSA, and 0.05% Procrine (registered trademark) 950. In addition, a type A influenza virus standard solution was serially diluted with a specimen extract to obtain a sample for sensitivity confirmation.

6). Color intensity measurement The test strip prepared in 4 above was immersed in a sample for confirmation of sensitivity, and the color intensity of the line was measured 10 minutes later (Table 1). For the color intensity measurement, a color chart (0.25 to 4.0) with a value of 0.25 unit from the blue color sample was used, and the average value of n = 3 was defined as the color intensity of the sensitivity confirmation sample. In the case of black particles, a color development sample having a darkness similar to that of the blue color development sample was separately prepared and subjected to the same evaluation. The higher the numerical value, the higher the sensitivity, and 0.5 or higher is visually detectable.

  According to the evaluation in Table 1, by coating the surface of the hydrocarbon-based fine particles with a polymer containing a π-conjugated compound, the surface of the same hydrocarbon-based fine particles can be compared with colored particles that do not include the π-conjugated compound. It can be seen that colored particles having a deep color and excellent visibility can be obtained.

  According to the present invention, colored particles for immunochromatography that can maintain the surface composition of latex particles and exhibit a deep color tone can be obtained because the composition itself that forms the surface of the particles exhibits colorability, so that it is darker than before. Colored particles for immunochromatography that can be colored and have excellent visibility, and immunochromatographic reagents using the particles can be provided.

Claims (9)

  A colored particle for immunochromatography, comprising a polymer containing a π-conjugated compound as a component constituting the surface.   The colored particles for immunochromatography according to claim 1, wherein the colored particles have an average particle size of 50 to 1000 nm.   The colored particles for immunochromatography according to claim 1 or 2, wherein the surface of the hydrocarbon fine particles is coated with a polymer containing a π-conjugated compound.   The immunochromatography according to any one of claims 1 to 3, wherein the polymer containing a π-conjugated compound is at least one selected from the group consisting of polyacetylene, polyaniline, polyfuran, polypyrrole, and polythiophene. Colored particles. Hydrocarbon fine particles
One or more kinds selected from the group consisting of a polymerizable monomer having a phenyl group, a polymerizable monomer having a methacryloyl group, a polymerizable monomer having an acryloyl group,
The colored particles for immunochromatography according to claim 3 or 4, wherein a polymerizable monomer having a phenyl group and a sulfonate is copolymerized.   The polymerizable monomer having a sulfonate salt is present when the surface of the hydrocarbon fine particles is coated with a polymer containing a π-conjugated compound. Colored particles for immunochromatography.   The colored particles for immunochromatography according to any one of claims 1 to 6, wherein the colored particles are black particles.   A diagnostic immunochromatographic reagent using the colored particles for immunochromatography according to any one of claims 1 to 7.   An immunochromatographic measurement method using the immunochromatographic reagent according to claim 8.