Thiol-ene grafting of silica particles with three-dimensional branched copolymer for HILIC/cation-exchange chromatographic separation and N-glycopeptide enrichment

Three-dimensional branched copolymer, with N,N'-methylene bisacrylamide as the crosslinker and 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt as the monomer, was grafted from silica particles by thiol-ene click reaction. The obtained hydrophilic material with sulfonic acid groups was successfully applied for chromatography separation and glycopeptide enrichment. The separation mechanism was proven as the mixed mode of hydrophilic interaction and cation-exchange by investigating the effect of various chromatographic factors on the retention of polar analytes. By such mixed-mode chromatography, nucleosides, nucleobases, and acidic compounds were successfully separated. The column efficiency was up to 136,000 theoretical plates m(-1) for cytidine, which was much higher than those of previous reports. Furthermore, benefitting from the large amount of hydrophilic groups provided by the branched copolymer, the material was used for the selective enrichment of glycopeptides. Results demonstrated the great potential of such material for chromatography separation and glycoproteome analysis.