Synthesis of a hydrophilic maltose functionalized Au NP/PDA/Fe3O4-RGO magnetic nanocomposite for the highly specific enrichment of glycopeptides
The development of methods to isolate and enrich low-abundance glycopeptides is an important prerequisite for glycoproteomics research. In this study, a hydrophilic maltose functionalized Au nanoparticle (NP)/polydopamine (PDA)/Fe3O4-reduced graphene oxide (RGO) nanocomposite has been successfully synthesized in mild conditions. The bioadhesive polydopamine film was prepared by self-polymerization on the surface of Fe3O4–graphene oxide, which not only prevents the agglomeration of the graphene sheets and enhances the specific surface area, but also facilitates the Au NP immobilization. A great number of loading Au NPs possess the highly available surface area for the immobilization of the high density of the thiol-terminated maltose via Au–S bonds. The resulting Au NP-maltose/PDA/Fe3O4-RGO nanocomposite exhibits excellent environmental stability, good biocompatibility and water dispersibility. Furthermore, the highly loaded Fe3O4 NPs make the enrichment very convenient. With all of these advances, the novel Au NP-maltose/PDA/Fe3O4-RGO nanocomposite presents selective enrichment of the glycopeptides from a low concentration of horseradish peroxidase tryptic digest (0.1 ng μL−1).