Ultrathin Au nanowires assisted magnetic graphene-silica ZIC-HILIC composites for highly specific enrichment of N-linked glycopeptides

•L-Cys functionalized magnetic graphene oxide was conveniently preapred for efficient enrichment of glycopeptides.•The ultrathin Au nanowires provided numerous of reaction sites and were easily grafted with an abundant amount of L-Cys for the enrichment of glycopeptides.•The prepared composites exhibited superior performance in glycopeptide enrichment.•The proposed method possesses great application potential in glycopeptide enrichment for complex biological samples enrichment.

Protein glycosylation has been proven to participate in a variety of complex biological processes; however, the low abundance of glycopeptides in natural samples makes it essential to develop methods to isolate and enrich glycopeptides. In this study, a novel ultrathin Au nanowire assisted zwitterionic hydrophilic magnetic graphene oxide (GO-Fe3O4/SiO2/AuNWs/L-Cys) was synthesized with the good biocompatibility of GO, strong magnetic responses of Fe3O4, large surface area of ultrathin Au nanowires and excellent hydrophilicity of L-Cys via four simple and rapid steps. The ultrathin Au nanowires have a one-dimensional structure and were easily grafted with an abundant amount of L-Cys for the enrichment of glycopeptides. After the GO-Fe3O4/SiO2/AuNWs/L-Cys composites were applied to glycopeptide enrichment, 26 glycopeptides from a human IgG digest could be identified, with a detection limit as low as 10 fmol. Due to the abundant amount of grafted L-Cys, the composites also showed a large binding capacity (150 μg mg−1). Furthermore, the composites were applied for the analysis of real biological samples. A total of 793 glycopeptides from 467 glycoproteins were identified in three replicate analyses of 40 μg of mouse liver proteins. The results demonstrated the great potential of GO-Fe3O4/SiO2/AuNWs/L-Cys composites for the analysis of glycoproteins.

Graphical abstractSynthetic process of GO-Fe3O4/SiO2/AuNWs/L-Cys and analysis of glycopeptides using GO-Fe3O4/SiO2/AuNWs/L-Cys.Download high-res image (156KB)Download full-size image