Maltose-Functionalized Hydrophilic Magnetic Nanoparticles with Polymer Brushes for Highly Selective Enrichment of N-Linked Glycopeptides

Efficient enrichment glycoproteins/glycopeptides from complex biological solutions are very important in the biomedical sciences, in particular biomarker research. In this work, the high hydrophilic polyethylenimine conjugated polymaltose polymer brushes functionalized magnetic Fe 3 O 4 nanoparticles (NPs) denoted as Fe 3 O 4 -PEI-pMaltose were designed and synthesized via a simple two-step modification. The obtained superhydrophilic Fe 3 O 4 -PEI-pMaltose NPs displayed outstanding advantages in the enrichment of N-linked glycopeptides, including high selectivity (1:100, mass ratios of HRP and bovine serum albumin (BSA) digest), low detection limit (10 fmol), large binding capacity (200 mg/g), and high enrichment recovery (above 85%). The above-mentioned excellent performance of novel Fe 3 O 4 -PEI-pMaltose NPs was attributed to graft of maltose polymer brushes and efficient assembly strategy. Moreover, Fe 3 O 4 -PEI-pMaltose NPs were further utilized to selectively enrich glycopeptides from human renal mesangial cell (HRMC, 200 μg) tryptic digest, and 449 N-linked glycopeptides, representing 323 different glycoproteins and 476 glycosylation sites, were identified. It was expected that the as-synthesized Fe 3 O 4 -PEI-pMaltose NPs, possessing excellent performance (high binding capacity, good selectivity, low detection limit, high enrichment recovery, and easy magnetic separation) coupled to a facile preparation procedure, have a huge potential in N-glycosylation proteome analysis of complex biological samples.