Design of Magnetic Cyanidin Adsorbent for Efficient Enrichment of Glycopeptides Based on Synergistic Hydrophilic and Electrostatic Interactions

As one of the most prevalent and crucial post-translational modifications, glycosylation plays a role in diverse biological processes, and its abnormal expression is closely associated with various diseases. The direct mass spectrometry analysis of glycopeptides is still a challenge due to their low abundance and the strong ion inhibitory effect from unmodified proteins. In this study, we developed a magnetic cyanidin material and facilely realized efficient glycopeptide enrichment based on synergistic hydrophilic-electrostatic interactions. With HRP as the standard protein, high sensitivity (0.1 fmol/μL), selectivity (1:1000), reusability (7 cycles), batch-to-batch reproducibility, and binding capacity (100 mg/g) were achieved. The developed method was further applied to glycopeptide detection in real human saliva samples, and obvious characteristic glycopeptide peaks were detected after enrichment. In addition, 101 intact glycopeptides derived from 44 glycoproteins were successfully identified in HepG2 cells, demonstrating the practical application value of the synthesized material in glycoproteomic research.