One-Step Preparation of Zwitterionic-Rich Hydrophilic Hydrothermal Carbonaceous Materials for Enrichment of N-Glycopeptides

Two kinds of novel zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) materials decorated with phosphorylcholine or sulfobetaine type zwitterionic groups were facilely synthesized employing hydrothermal carbonization (HTC) reaction, in which sustainable carbohydrate (glucose) could be converted into functionalized carbonaceous materials with strong hydrophilicity using a one-step and environmentally mild process. The properties of obtained materials were characterized by helium ion microscopy (HIM), N2 adsorption/desorption measurement, static water contact angle measurement, elemental analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ζ-potential. As a result, 26 N-glycopeptides with S/N above 20 could be detected from 150 fmol IgG digests after hydrophilic interaction chromatography (HILIC) enrichment by using as-synthesized material HTC-Glc-10%MPC. The limit of detection in matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF MS) analysis was as low as 5 fmol and enrichment selectivity reached 100:1. Furthermore, 175 N-glycosylation sites in 285 N-glycopeptides from 92 glycoproteins were identified from 2 μL of human serum. This work provided a new, simple, and green way to synthesize an N-glycopeptide enrichment material for liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) analysis of glycoproteomes.