Metal-resin composite and use thereof

An analyte measurement method for detecting or quantifying an analyte included in a sample, the method comprising the following Processes (I) to (III) that are performed using a test strip for lateral flow chromatography that includes a membrane and a determination section in which a capture ligand that specifically binds to the analyte is fixed to the membrane;

• Process (I):
• a process in which the analyte included in the sample is brought into contact with a labeled antibody obtained by labeling an antibody that specifically binds to the analyte with a metal-resin composite;
• Process (II):
• a process in which a composite including the analyte and the labeled antibody formed in Process (I) is brought into contact with the capture ligand in the determination section;
• and
• Process (III):
• a process in which a color development intensity derived from localized surface plasmon resonance and/or light energy absorption due to electron transition of the metal-resin composite is measured,
• wherein the metal-resin composite includes resin particles and a plurality of metal particles fixed to the resin particles, the resin particles comprise a nitrogen-containing polymer selected from the group consisting of poly-2-vinylpyridine, poly-3-vinylpyridine, and poly-4-vinylpyridine, the metal particles are particles of gold, platinum, palladium, or an alloy thereof, the metal particles comprise metal particles that are completely enclosed in each of the resin particles, metal particles having a portion that is embedded in each of the resin particles and a portion that is exposed to an outside of each of the resin particles, and metal particles that are adhered to a surface of the resin particles, and 20 wt % or less of the metal particles are the metal particles that are adhered to the surface of the resin particles, and in a range of pH 3 to pH 10, a maximum value of a zeta potential of the metal-resin composite is 5 mV or higher, and a minimum value thereof is −5 mV or lower,
• at least one anionic functional group and at least one cationic functional group are present on a surface of each of the resin particles or the metal-resin composite, wherein the at least one anionic functional group is selected from the group consisting of a carboxyl group, a sulfonic acid group and a phosphonic acid group, and the at least one cationic functional group comprises a nitrogen-containing group, and
• at least a portion of the metal particles are distributed in a planar direction and in a depth direction in each of the resin particles in a range of the first 50% from the surface of each of the resin particles in a resin particle radius direction.

An analyte measurement kit for detecting or quantifying an analyte included in a sample, comprising:

• a test strip for lateral flow chromatography including a membrane and a determination section in which a capture ligand that specifically binds to the analyte is fixed to the membrane;
• and
• a detection reagent including a labeled antibody obtained by labeling an antibody that specifically binds to the analyte with a metal-resin composite,
• wherein the metal-resin composite has a structure in which a plurality of metal particles are fixed to resin particles, the resin particles comprise a nitrogen-containing polymer selected from the group consisting of poly-2-vinylpyridine, poly-3-vinylpyridine, and poly-4-vinylpyridine, the metal particles are particles of gold, platinum, palladium, or an alloy thereof, the metal particles comprise metal particles that are completely enclosed in each of the resin particles, metal particles having a portion that is embedded in each of the resin particles and a portion that is exposed to an outside of each of the resin particles, and metal particles that are adhered to a surface of the resin particles, and 20 wt % or less of the metal particles are the metal particles that are adhered to the surface of the resin particles, and in a range of pH 3 to pH 10, a maximum value of a zeta potential is 5 mV or higher and a minimum value thereof is −5 mV or lower,
• at least one anionic functional group and at least one cationic functional group are present on a surface of each of the resin particles or the metal-resin composite, wherein the at least one anionic functional group is selected from the group consisting of a carboxyl group, a sulfonic acid group and a phosphonic acid group, and the at least one cationic functional group comprises a nitrogen-containing group, and
• at least a portion of the metal particles are distributed in a planar direction and in a depth direction in each of the resin particles in a range of the first 50% from the surface of each of the resin particles in a resin particle radius direction.

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

• a membrane;
• a determination section in which a capture ligand that specifically binds to the analyte is fixed to the membrane in a direction in which the sample is developed;
• and
• a reaction section including a labeled antibody obtained by labeling an antibody that specifically binds to the analyte with a metal-resin composite upstream from the determination section,
• wherein the metal-resin composite has a structure in which a plurality of metal particles are fixed to resin particles, the resin particles comprise a nitrogen-containing polymer selected from the group consisting of poly-2-vinylpyridine, poly-3-vinylpyridine, and poly-4-vinylpyridine, the metal particles are particles of gold, platinum, palladium, or an alloy thereof, the metal particles comprise metal particles that are completely enclosed in each of the resin particles, metal particles having a portion that is embedded in each of the resin particles and a portion that is exposed to an outside of each of the resin particles, and metal particles that are adhered to a surface of the resin particles, and 20 wt % or less of the metal particles are the metal particles that are adhered to the surface of the resin particles, and in a range of pH 3 to pH 10, a maximum value of a zeta potential is 5 mV or higher and a minimum value thereof is −5 mV or lower,
• at least one anionic functional group and at least one cationic functional group are present on a surface of each of the resin particles or the metal-resin composite, wherein the at least one anionic functional group is selected from the group consisting of a carboxyl group, a sulfonic acid group and a phosphonic acid group, and the at least one cationic functional group comprises a nitrogen-containing group, and
• at least a portion of the metal particles are distributed in a planar direction and in a depth direction in each of the resin particles in a range of the first 50% from the surface of each of the resin particles in a resin particle radius direction.