International Classification:
G01N033/53
G01N033/569
Abstract:
A method for detecting the occurrence of a biological reaction or quantitating its result employing superparamagnetic particles is disclosed. The particles are first conjugated or adsorbed to identical biomolecules which are members of a biological binding pair and the conjugates or adsorbates so formed are then contacted with a liquid or solid sample known to contain, or suspected of containing, molecules that are the biological binding partners of the biomolecules in the conjugates or adsorbates. The conjugates or adsorbates are digested with the liquid or solid sample for a time sufficient to enable the formation of a tightly bound, three-dimensional mass comprised of interlinked biomolecules and bound superparamagnetic particles. The mass is exposed to a magnetic filed for the shortest period necessary to induce magnetization of the superparamagnetic particles, whereupon the magnetic field is immediately removed. It has been found that the mass exhibits, in concert, a measurable nonpermanent magnetization which persists for at least 20 minutes following exposure to the magnetic field. If it is desired only to confirm that reaction occurred, this may be done by confirming the existence of a magnetic signal with a suitable instrument. If a quantitative result is desired, the intensity of the magnetization may be measured over time and correlated to the quantitative concentration, or known number, of one of the biomolecules in the biological binding pair.