Specific Isolation of Immunoglobulin G from Human Serum by Using Thiophilic Magnetic Microspheres

A rapid and effective technique to specifically isolate immunoglobulin G(IgG) from human serum is developed based on the micro-sized thiophilic paramagnetic polymer beads.These magnetic beads were synthesized with vinyl acetate and divinylbenzene by microsuspension polymerization in the presence of the modified magnetite nanoparticles.Then,the thiophilic ligands of divinylsulphone and 2-mercapto-benzothiazole were grafted on the surface of these magnetic beads through Michael addition reaction.Depending on the cooperative action of divinylsulphone and 2-mercapto-benzothiazole,these magnetic particles exhibit a strong specificity towards IgG.Furthermore,this specific binding of IgG on the magnetic beads is performed at low salt concentration.It is much favorable to preserve the bioactivity of the antibodies and to increase the purity of IgG.However,the responding desorption is heavily depended on the types of salt in elution.Because the selective recognition between the thiophilic ligands and IgG is attributed to electron donor-acceptor(EDA) interaction,there is no obvious effect of temperature on the adsorption.Therefore,this isolation could be fully carried out at room temperature.Based on the magnetic separation technique and the appropriate magnetic particles,the isolation procedure was so rapid that 1.5 hours was enough to extract 72% IgG(98mg) from 10mL human serum.