Magnetic immunoassay system

Abstract

A magnetic immunoassay system with a mechanism for compensating the direct current residual magnetic field in the vicinity of the specimen measurement position, in a direction perpendicular to the magnetic marker direction of magnetization for the measurement target. This invention reduces the effects of the magnetic field emitted from the unbound magnetic marker due to the residual magnetic field in the specimen solution and detects with high sensitivity the signal of the bound target magnetic marker. The magnetic field at the measurement position is regulated so as to intersect the direction of magnetization of the magnetic marker for the measurement target, in order to make the magnetization direction of the magnetic marker that is unbound due to residual magnetism or remanence in the sample solution, intersect the magnetization direction of the magnetic marker for the measurement target. The signal of the bound target magnetic marker can be therefore measured with high sensitivity since it is isolated from the unbound magnetic marker signal.

1 . A magnetic immunoassay system comprising:
 a nonmagnetic reaction chamber where an antibody for binding to an antigen for detection is affixed to one surface of the chamber;   a mechanism for moving the reaction chamber;   a magnetic sensor for measuring the magnetic signal from the sample in a liquid state containing antibodies labeled with a magnetic nanoparticles for binding to the antigen to be detected, is injected;   a magnetic shield for blocking the magnetic noise in the periphery of the magnetic sensor;   a mechanism for making a first summed magnetization direction of magnetic nanoparticles labeling the antibodies bound to sample antigen bound to antibodies affixed to the nomnagnetic reaction chamber; intersect a second summed magnetization direction of only unbound magnetic nanoparticles for labeling antibodies and magnetic nanoparticles labeling antibodies bound to sample antigen that are not bound to antibodies affixed to the nonmagnetic reaction chamber; and   a means for processing signals from the magnetic sensor.   
   
   
       2 . The magnetic immunoassay system according to  claim 1 , wherein the magnetic sensor is a superconducting quantum interference device. 
   
   
       3 . The magnetic immunoassay system according to  claim 1 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, applies a magnetic field acting in a direction perpendicular to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       4 . The magnetic immunoassay system according to  claim 2 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, applies a magnetic field acting in a direction perpendicular to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       5 . The magnetic immunoassay system according to  claim 1 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, applies a magnetic field acting in a direction parallel to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       6 . The magnetic immunoassay system according to  claim 2 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, applies a magnetic field acting in a direction parallel to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       7 . The magnetic immunoassay system according to  claim 1 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, is an magnetic shield for blocking the magnetic field perpendicular to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       8 . The magnetic immunoassay system according to  claim 2 , wherein the mechanism for making a first summed magnetization direction intersect the second summed magnetization direction, is an RF shield for blocking the magnetic field perpendicular to the pickup coil surface of the magnetic sensor for detecting magnetism. 
   
   
       9 . The magnetic immunoassay system according to  claim 7 , wherein the magnetic shield is comprised of cylindrical-shaped high permeability material formed with an opening on both side surfaces. 
   
   
       10 . The magnetic immunoassay system according to  claim 8 , wherein the magnetic shield is comprised of cylindrical-shaped high permeability material formed with an opening on both side surfaces. 
   
   
       11 - 20 . (canceled)