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<sub>3</sub>O<sub>4</sub> nanoparticles (NPs) denoted as Fe<sub>3</sub>O<sub>4</sub>–PEI–pMaltose were designed and synthesized
via a simple two-step modification. The obtained superhydrophilic
Fe<sub>3</sub>O<sub>4</sub>–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<sub>3</sub>O<sub>4</sub>–PEI–pMaltose NPs was attributed to graft of
maltose polymer brushes and efficient assembly strategy. Moreover,
Fe<sub>3</sub>O<sub>4</sub>–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<sub>3</sub>O<sub>4</sub>–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