Preparation of functionalized Fe₃O₄@SiO₂ magnetic nanoparticles for monoclonal antibody purification

Magnetic Fe₃O₄@SiO₂ nanoparticles with superparamagnetic properties were prepared via a reverse microemulsion method at room temperature. The as-prepared samples were characterized by transmission electron microscopy(TEM), X-ray diffractometry(XRD), and vibrating sample magnetometry(VSM). The Fe₃O₄@SiO₂ nanopar-ticles were modified by (3-aminopropyl)triethoxysilane(APTES) and subsequently activated by glutaraldehyde(Glu). Protein A was successfully immobilized covalently onto the Glu activated Fe3O4@SiO2 nanoparticles. The adsorption capacity of the nanoparticles was determined on an ultraviolet spectrophotometer(UV) and approximately up to 203 mg/g of protein A could be uniformly immobilized onto the modified Fe₃O₄@SiO₂ magnetic beads. The core-shell of the Fe₃O₄@SiO₂ magnetic beads decorated with protein A showed a good binding capacity for the chimeric anti-EGFR monoclonal antibody(anti-EGFR mAb). The purity of the anti-EGFR mAb was analyzed by virtue of HPLC. The protein A immobilized affinity beads provided a purity of about 95.4%.