A combination of "thiol-ene" click chemistry and surface initiated atom transfer radical polymerization: Fabrication of boronic acid functionalized magnetic graphene oxide composite for enrichment of glycoproteins.

An efficient glycoproteins enrichment platform is one of vital preprocessing steps in biomarker research and in particular glycoproteomics. In this work, a well-defined boronic acid functionalized magnetic graphene oxide nanocomposite (Fe3O4-GO@PAAPBA) was synthesized for the selective enrichment of glycoproteins from complex biological samples via a novel strategy based on the "thiol-ene" click chemistry and surface initiated atom transfer radical polymerization (SI-ATRP). The initiator of ATRP was anchored to the surface of substrate through "thiol-ene" click reaction. The product Fe3O4-GO@PAAPBA was successfully synthesized in following SI-ATRP. The Fe3O4-GO@PAAPBA nanocomposite was characterized by transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and thermogravimetric analysis. The adsorption capacity of Fe3O4-GO@PAAPBA towards ovalbumin (OVA) and transferrin (Trf) is 471mgg-1 and 450mgg-1, respectively. The nanocomposite also featured good selectivity to glycoproteins in the mixture of glycoproteins and non-glycoproteins at alkaline (pH 9.0) and physiological conditions (pH 7.4). Furthermore, it can be applied to extract glycoproteins directly from egg white samples. These results have indicated that Fe3O4-GO@PAAPBA was a potential affinity material in glycoprotein analysis.