Development of a liquid phase immunoassay by time-dependent measurements of the transient magneto-optical birefringence using functionalized magnetic nanoparticles

The transient magneto-optical birefringence was investigated as a new liquid phase immunoassay technique. Specifically binding magnetic probes using monoclonal as well as polyclonal antibodies were investigated. The detection limit for optimized magnetic nanoparticles was determined. Binding experiments of polyclonal probes with their specific antigen yielded increased particle sizes as determined from magneto-optical relaxation curves. Aggregation of magnetic probes due to cross-linking caused gradually decreased signal intensity.