To prepare magnetic nanoparticles and to explore its application in radioimmunoassay (RIA)

aqueous decanoic acid-coated Fe3O4 magnetic nanoparticles were synthesized by chemical coprecipitation with Fe2+ and Fe3+ ions included in microemulsions with ammonia water. The sheep anti-rabbit IgG was immobilized into the magnetic nanoparticles by physical adsorption. The complex of the magnetic nanoparticles and the sheep anti-rabbit IgG (magnetic nanoparticle second antibody) was then used as magnetic separation carrier for RIA. The magnetic nanoparticle size

size distributions

polydispersity etc were determined by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). Some influence factors such as of buffer pH used for immobilizing sheep anti-rabbit IgG

amount of sheep anti-rabbit IgG

time of immobilizing sheep anti-rabbit IgG on specific and nonspecific binding of magnetic nanoparticle second antibody in RIA were studied. The results indicated that the average diameter of the decanioc acid-coated Fe3O4 nanoparticle and magnetic nanoparticle second antibody is 10-20 run and around 1000 nm

respectively. The second antibody labeled magnetic nanoparticle can be used in RIA. In conclusion the magnetic nanoparticle second antibody is characterized by the simplicity

time-saving in preparation

low cost and the conveniences of magnetic separation. So it has practical value in medical application.