Metal-resin composite, labeling substance, immunological assay method, immunological assay reagent, analyte measurement method, analyte measurement kit, and test strip

An analyte measurement method for detecting or quantifying an analyte contained in a sample, the method comprising:

• using a test strip for lateral flow chromatography including a membrane and a determination part in which a capture ligand that specifically binds to the analyte is immobilized on the membrane performing following steps (I) to (III) including:
• step (I):
• a step of bringing the analyte contained in the sample into contact with a labeled antibody in which an antibody that specifically binds to the analyte is labeled with a metal-resin composite;
• step (II):
• a step of bringing the composite including the analyte and the labeled antibody formed in step (I) into contact with the capture ligand at the determination part;
• and
• step (III):
• a step of measuring color intensity derived from light energy absorption due to localized surface plasmon resonance and/or electron transition of the metal-resin composite,
• wherein the metal-resin composite has a resin particle and a plurality of metal particles immobilized on the resin particle, a maximum value of zeta potential is 5 mV or more in a range of pH 3 to pH 6, a minimum value of zeta potential is −20 mV or less in a range of pH 8 to pH 10, a zero charge point of zeta potential exists in a range of pH 6.1 to pH 9.0, the metal particles are particles of gold or an alloy thereof, and a CV value (Coefficient of Variation) of a particle diameter thereof is 0.45 or less.

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

• a test strip for lateral flow chromatography including a membrane and a determination part in which a capture ligand that specifically binds to the analyte is immobilized on the membrane;
• and
• a detection reagent including a labeled antibody in which an antibody that specifically binds to the analyte is labeled with a metal-resin composite,
• wherein the metal-resin composite has a structure in which a plurality of metal particles are immobilized on the resin particle, a maximum value of zeta potential is 5 mV or more in a range of pH 3 to pH 6, a minimum value of zeta potential is −20 mV or less in a range of pH 8 to pH 10, a zero charge point of zeta potential exists in a range of pH 6.1 to pH 9.0, the metal particles are particles of gold or an alloy thereof, and a CV value (Coefficient of Variation) of a particle diameter thereof is 0.45 or less.

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

• a membrane;
• a determination part in which a capture ligand that specifically binds to the analyte is immobilized on the membrane in a direction in which the sample develops;
• and
• a reaction part including a labeled antibody in which an antibody that specifically binds to the analyte is labeled with a metal-resin composite, located upstream side of the determination part,
• wherein the metal-resin composite has a structure in which a plurality of metal particles are immobilized on a resin particle, a maximum value of zeta potential is 5 mV or more in a range of pH 3 to pH 6, a minimum value of zeta potential is −20 mV or less in a range of pH 8 to pH 10, a zero charge point of zeta potential exists in a range of pH 6.1 to pH 9.0, the metal particles are particles of gold or an alloy thereof, and a CV value (Coefficient of Variation) of a particle diameter thereof is 0.45 or less.