Approaches to paramagnetic separations in biology and medicine

Exposure to paramagnetic cations, such as Er3+, endows many types of particles with positive magnetic susceptibilities. This discovery has served as the basis for our investigations into methods of separating particulate biological materials magnetically. As part of this enterprise, the "isomagnetic" method has been developed to permit the accurate determination of the magnetic susceptibilities of individual particles. By manipulating the experimental conditions, the particles' magnetic behavior can be controlled to permit the isolation of specific populations of particles from heterogeneous mixtures. Using the Ferro- graph Analyzer, we have applied these principles to the magnetic retrieval and separation of wear particles from human synovial fluid and of various types of eukaryotic and prokaryotic cells.