Preparation and Characterization of PEGylated Thiophilic Nanoparticles for Rapid Antibody Separation

Magnetic nanoparticles with novel core-shell structure were prepared for immunoglobulin (IgG) separation, in which thiophilic property of sulfone groups and protein resistance of poly(ethylene glycol) (PEG) moieties were integrated. The step-wise surface reactions on the nanoparticles were characterized by ¹H nuclear magnetic resonance (NMR) and surface zeta potential measurements. With human IgG and bovine serum albumin (BSA) as model proteins, the effects of PEG chain length, conjugation group, solution pH and salt concentration on IgG selectivity were investigated using static adsorption experiments. The experiment results showed that mPEG2000-NH₂ modified magnetic nanoparticles had an adsorption capacity of 132.8 mg g^?1 and selectivity of 32.5 towards IgG under the condition of pH 7.45 and 0.15 M NaCl. In complex biological fluids, the PEG modified magnetic nanoparticles could separate IgG from fetal calf serum and Omalizumab from cell culture supernatant with purities of 96% and 99%, respectively. Moreover, the binding affinities of the proposed core-shell structure towards IgG from four animal species (human, bovine, rabbit and goat) were quantified by bio-layer interferometer (BLI). The results showed that the selectivity of this structure towards IgG varied from traditional Protein A method, suggesting its potentials in rapid separation and purification of IgG with low affinity towards Protein A.