Resin-metal composite, marker, immunoassay method, immunoassay reagent, method for measuring analyte, analyte measurement kit, and lateral-flow chromatographic test strip

1. A resin-metal composite, comprising a structure formed by immobilizing a plurality of metal particles on a resin particle, characterized in that

the plurality of metal particles includes:

first particles, having a portion exposed from the resin particle; and

second particles, completely encased in the resin particle;

among the first particles and the second particles, at least portions of the particles are three-dimensionally distributed in a surface section of the resin particle, and 60 wt % to 100 wt % of the metal particles exist in the surface section,

relative to the weight of the resin-metal composite, the quantity of the carried metal particles is within a range from 26.2 wt % to 55.7 wt %,

the resin particle is a particle comprising a polymer, the polymer being provided with, in a repeating unit thereof, a substituent group capable of adsorbing metal ions, and being selected from a group consisting of poly-2-vinylpyridine, poly-3-vinylpyridine, poly-4-vinylpyridine, poly-2-(diisopropylamino)ethyl methacrylate, polypyrrole, polyamide, polyamic acid, and polyimide,

the first particles and the second particles comprise gold,

the average particle size of the metal particles is within a range from 22 nm to 50 nm,

an average particle size of the resin-metal composite is within a range from 312 nm to 650 nm, and

the first particles include partially exposed metal particles and surface-adsorbed metal particles, wherein the surface-adsorbed metal particles are 20 wt % or less of the metal particles.

2. The resin-metal composite according to claim 1 , wherein 5 wt % to 90 wt % of the metal particles existing in the surface section are the first particles.

3. The resin-metal composite according to claim 1 , wherein the metal particles are gold particles.

4. A marker, comprising the resin-metal composite according to claim 1 .

5. The marker according to claim 4 , used in adsorbing an antigen or an antibody on the surface of the resin-metal composite.

6. An immunoassay method, characterized by using the marker according to claim 4 .

7. A immunoassay reagent, comprising the resin-metal composite according to claim 1 .

8. A method for measuring analyte, assaying or quantifying an analyte contained in a sample, characterized by

using a lateral-flow chromatographic test strip comprising a membrane and a determination portion formed by immobilizing capturing ligands specifically bound with the analyte on the membrane to carry out steps including step (I) to step (III) hereinafter:

step (I): step of making the analyte contained in the sample contact with a marked antibody formed by utilizing the resin-metal composite according to claim 1 to mark an antibody specifically bound with the analyte;

step (II): step of making the composite containing the analyte and the marked antibody formed in step (I) contact with the capturing ligands in the determination portion; and

step (III): step of determining colored intensity derived from the localized surface plasmon resonance of the resin-metal composite.

9. An analyte measurement kit, using a lateral-flow chromatographic test strip, used to assay or quantify an analyte contained in a sample, and the analyte measurement kit comprising:

the lateral-flow chromatographic test strip, comprising a membrane and a determination portion formed by immobilizing capturing ligands specifically bound with the analyte on the membrane; and

an assay reagent, containing a marked antibody formed by utilizing the resin-metal composite according to claim 1 to mark an antibody specifically bound with the analyte.

10. A lateral-flow chromatographic test strip, used to assay or quantify an analyte contained in a sample, comprising

a membrane;

a determination portion, formed by immobilizing capturing ligands specifically bound with the analyte on the membrane in the spreading direction of a sample; and

a reaction portion, comprising a marked antibody formed by utilizing the resin-metal composite according to claim 1 to mark an antibody specifically bound with the analyte further upstream than the determination portion.