Because many glycoproteins (including glycopropeptides) of biological importance are present in very low abundance in samples while interfering substances are usually present in high abundance,the selective enrichment of glycoproteins is a key and challenging issue in proteomic analysis.Boronic acids can react with glycoproteins to form covalent complexes at basic pH while the complexes dissociate when the environment is switched to acidic pH.Due to their unique capability of selective extraction of glycoproteins,boronate affinity materials have been getting increasing attention in proteomics in recent years.