Novel synthesis of glucose functionalized magnetic graphene hydrophilic nanocomposites via facile thiolation for high-efficient enrichment of glycopeptides.

High-efficient enrichment of glycopeptides prior to mass spectrometry is essential for glycoproteomics analysis. Hydrophilic interaction chromatography (HILIC) approach is a prominent strategy for glycopeptides identification. In this work, glucose functionalized magnetic graphene hydrophilic nanocomposite (MagG/Au/Glu) was synthesized as a novel HILIC material via a facile surface modification strategy. Different from previous click synthesis of saccharides-functionalized materials, glucose was easily thiolated via Traut's reagent and then immobilized on the materials via efficient Au-S coupling, greatly simplifying the synthesis process. Combining the rapid magnetic response, huge surface area from graphene and excellent hydrophilicity from glucose, MagG/Au/Glu nanocomposites afforded convenience of the operation and affinity for glycopeptides. Thus, the nanocomposites exhibited superior performance of high sensitivity, selectivity and reusability in glycopeptide enrichment from tryptic digests of standard glycoprotein HRP. Encouragingly, with the usage of MagG/Au/Glu nanocomposites, a total of 305 glycopeptides assigned to 108 glycoproteins were identified from complex real sample human serum, indicating a great potential for the application of glycoproteomics research.