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 FeO nanoparticles (NPs) denoted as FeO-PEI-pMaltose were designed and synthesized via a simple two-step modification. The obtained superhydrophilic FeO-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 FeO-PEI-pMaltose NPs was attributed to graft of maltose polymer brushes and efficient assembly strategy. Moreover, FeO-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 FeO-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.