Synthesis of magnetic zwitterionic-hydrophilic material for the selective enrichment of N-linked glycopeptides.

In consideration of the close connection between glycopeptides and human diseases, the efficient method to separate and enrich glycopeptides from complex biological samples is urgently required. In the work, we developed a magnetic zwitterionic-hydrophilic material for highly effective separation and analysis of glycopeptides from complex samples. The FeO particles were covered with a thick layer of polymer by one-step reflux-precipitation polymerization (RPP), subsequently decorated by Au nanoparticles (Au NPs) through in situ reduction and finally modified with zwitterionic groups. The abundant zwitterionic sites facilitate the selective enrichment of glycopeptides. Besides, the prepared FeO@PGMA@Au-l-cys showed high detection sensitivity (5 fmol IgG digest), approving enrichment capacity (75mgg), satisfactory enrichment recovery (89.8%), and great performance in the analysis and profiling of low-abundance N-linked glycopeptides. Furthermore, the prepared material was employed in the enrichment of glycopeptides in intricate biological samples, and 774 unique N-glycosylation sites from 411 N-glycosylated proteins were reliably identified in three replicate analyses of a 75μg protein sample extracted from mouse liver, suggesting wide application prospect in glycoproteomics.