SnO2@Poly(HEMA-co-St-co-VPBA) Core-shell Nanoparticles Designed for Selectively Enriching Glycopeptides Followed by MALDI-MS Analysis

The core-shell boronic-acid functionalized nanoparticles SnO2@Poly(HEMA-co-St-co-VPBA) are designed for selectively enriching glycopeptides, followed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. Such 60 nm sized core-shell nanoparticles are prepared by means of copolymerization between 2-hydroxyethyl methacrylate (HEMA) grafted on SnO2 nanoparticles, styrene, and 4-vinylphenylboronic acid (VPBA). All of the synthesis procedures are completed within 3 h. Cyclic boronate esters form between boronic-acid groups on the polymer chains and cis-diol groups on glycopeptides, and thus almost all intact glycopeptides from low-abundant horseradish peroxidase (HRP) and bovine asialofetuin (ASF) are enriched with high selectivity and efficiency. After enrichment, both intact N- and O-glycopeptides are characterized by multistage MS. Furthermore, we successfully apply this method to the human serum sample for characterizing the target glycoproteins haptoglobin and alpha-l-acid-glycoprotein. The present selective enriching method followed by multistage-MS analysis is proven to be a good choice for routine glycopeptide characterization.