A highly selective hydrophilic sorbent for enrichment of N-linked glycopeptides

• A hyperbranched polyethylenimine-based sorbent for N-glycopeptides.
• Excellent selectivity for sialylated glycopeptides @ non-glycopeptides achieved.
• It possesses a large binding capacity of ∼220 mg/g towards fetuin.

Selective enrichment and purification of N-glycopeptides from complex biological samples is often a necessary step for effective identification of low abundance glycopeptides. A polyethylenimine functionalized sorbent described here demonstrates good enrichment ability and excellent selectivity towards acidic glycopeptides (e.g. sialylated glycopeptides), even at 1:3000 mass ratio of target glycopeptides and non-glycopeptides, which is much more superior to commercial ZIC-HILIC and other reported sorbents. It also shows effective enrichment for neutral glycopeptides (IgG). Another desirable feature of such sorbent is its large binding capacity (∼220 mg/g for fetuin).