Abstract: An ultra-sensitive laser magnetic immunoassay method comprising the steps of: labeling an antigen or antibody with micro-particles of a magnetic substance to form a magnetic-labeled body; subjecting a specimen and the magnetic-labeled body to an antigen-antibody reaction to form a reacted body-specimen complex; separating and removing unreacted body from the reacted complex; guiding and concentrating the reacted complex magnetically; irradiating the concentrated complex with a laser beam; detecting outgoing light from a measurement system to provide a quantitative result in the picogram range. An apparatus comprising a specimen container for storing a specimen labeled with magnetic micro-particles, concentration means for guiding and locally concentrating the specimen, a laser beam irradiating optical system for guiding a laser beam into the specimen, and a light receiving system arranged so as to detect outgoing beams from the specimen.

Abstract: A laser magnetic immunoassay (LMIA) technique is presented which combines the high detection sensitivity of the radioimmunoassay (RIA) technique with the simplicity of particle agglutination (PA) technique. The LMIA technique dispenses with the separation step of bound and free species (B/F separation), yet provides detectivity of the order of picogram of viral species per milliliter of analyte solution. The procedure includes of the steps of: preparing a superparamagnetic-labeled body of antigen or antibody; subjecting a specimen sample and the magnetic-labeled body to a specific immunoreaction to produce a reacted body; subjecting the reacted body containing both bound and free species to a spot magnetic field gradient; irradiating the spot with a laser beam; measuring the intensity of the outgoing light from the spot; and making a quantitative determination of the virus according to the time difference in the outgoing light signals generated by bound and free species.

Abstract: An in-situ laser magnetic immunoassay ("LMIA") method which eliminates the step of B/F separation generally required in the labeling method of immunoassays. The laser magnetic immunoassay permits a quantitative determination of a target immunological substance, for example, an antigen, an antibody, lymphocytes, viruses, tumorous cells and infections cells, in an analyte solution containing both bound and free species. A transitory increase in the magnetophoretic scattering of laser beam is observed when the analyte solution contains magnetic-labeled, bound target analyte, while no such increase is observed in a control test solution, containing only the relevant reagents. A magnetophoretic LMIA apparatus is provided which includes a magnetic gradient generating device which forms an integral part of the in-situ LMIA.