PEGylation of metal-organic framework for selective isolation of glycoprotein immunoglobulin G

Metal-organic frameworks (MOFs) have been gaining extensive popularity in the field of sample pretreatment due to their designable structures and easy-modifiable surfaces. Herein, zirconium-based MOFs UiO-66-NH2 is first coated with graphene oxide (GO) layer to enhance the stability, and then grafted with hydrophilic polyethylene glycol (PEG) via amidation reaction to give a product of hydrophilic MOF-based nanomaterial UiO@GO@PEG. The obtained nanoparticles exhibit typical hydrophilic interaction liquid chromatography (HILIC) behavior towards glycoproteins, making itself powerful adsorbent for the extraction of glycoproteins from complex matrices. Under pH 9.0, an adsorption capacity of 139.6 mg g−1 for glycoprotein immunoglobulin G (IgG) is achieved, and the retained IgG could be recovered by 0.5% (m/v) ammonium hydroxide (NH4OH) as stripping reagent with a recovery rate of 82.6%. Moreover, the UiO@GO@PEG shows excellent reusability in IgG isolation. The practicability of UiO@GO@PEG is verified by the selective isolation of IgG from human serum, demonstrating the purity of isolated IgG with SDS-PAGE assay.