Highly-sensitive magnetic marker for use in immunoreaction measurement

摘要

Disclosed are a highly-sensitive magnetic marker for use in measuring an immunoreaction with a SQUID magnetic sensor and the preparation thereof. The magnetic marker is composed of a magnetic fine particle and a polymer encapsulating the particle, wherein the particle diameter of the magnetic fine particle (preferably ferrite Fe₃O₄) is 20 to 40 nm and the external the diameter of the magnetic marker is 40 to 100 nm, the polymer having carboxyl groups on the surface thereof. The magnetic maker for a SQUID magnetic sensor is prepared by causing the surface of a magnetic fine particle to adsorb a hydrophilic macromonomer (preferably polyvinylpyrrolidone) having a polymerizable vinyl group at the terminal thereof and having a molecular weight of 500 to 1000, and then adding a monomer of a hydrophilic vinyl compound having carboxyl group and a crosslinking agent for carrying out copolymerization reaction.