Polyoxometalate-Coated Magnetic Nanospheres for Highly Selective Isolation of Immunoglobulin G.

Polyoxometalate [{a-PW11O39Zr(μ-OH)(H2O)}2]8- (POM1) is first prepared by sandwiching ZrIV among 2 mono-lacunary α-Keggin polyoxometalates, and then novel magnetic nanoparticles (NPs), Fe3O4@polyethyleneimine (PEI)@POM1, are fabricated by coating POM1 onto the surface of magnetic Fe3O4@PEI NPs under electrostatic interaction. The obtained Fe3O4@PEI@POM1 NPs are characterized by Fourier transform infrared, zeta potential, vibrating sample magnetometer, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Ascribed to the hydrogen-bonding and electrostatic interactions, the NPs exhibit high adsorption selectivity toward IgG, and the adsorption capacity is high up to 304 mg g-1 under optimal adsorption conditions. By using 0.01% cetyl trimethylammonium bromide to strip the adsorbed protein species, an elution efficiency of 95% is achieved. The feasibility of Fe3O4@PEI@POM1 NPs in real-world sample assay has been demonstrated by the selective isolation of IgG heavy chain and light chain from human serum, as confirmed by the sodium dodecyl sulfate polyacrylamide gel electrophoresis assay.