Glucose-6-Phosphate-Functionalized Magnetic Microsphere as Novel Hydrophilic Probe for Specific Capture of N-Linked Glycopeptides.

Developing cost-effective approaches based on hydrophilic interaction liquid chromatography (HILIC) has been the main tendency for low-abundance glycopeptides capture before LC-MS/MS analysis. Carbohydrates with outstanding biocompatibility and hydrophilicity are ubiquitous in the kingdoms of animal and plant and could be a wonderful choice as functional groups for glycopeptides enrichment. In this work, glucose-6-phosphate, as one of the indispensable cogs in pivotal metabolic wheels of life, was chosen as functionalized groups to be grafted onto the surface of FeO microspheres via one-step surface fabrication strategy. The acquired hydrophilic FeO@G6P microspheres showed superior enrichment performance for glycopeptides with high sensitivity (0.5 fmol/μL) and high selectivity (1:100) and good repeatability (10 times at least). Furthermore, the FeO@G6P microspheres also exhibited enrichment ability for glycopeptides in different biosamples. A total of 243 glycopeptides assigned to 92 glycoproteins and 183 glycopeptides corresponding to 74 different glycoproteins was identified from merely 2 μL of serum and saliva, respectively.