Core-shell structured magnetic metal-organic framework composites for highly selective enrichment of endogenous N-linked glycopeptides and phosphopeptides

In this work, core-shell structured magnetic metal-organic framework composites denoted as Fe3O4 @MIL-100(Fe) were synthesized by means of a layer-by-layer assembly method selecting Fe as metal center and 1,3,5-benzenetricarboxylic acid as organic ligand. The as-prepared material exhibited outstanding sensitivity (0.1 fmol/mu L), good selectivity (1:20 and 1:50 respectively), excellent ability of size-exclusion (1: 500), fine reusability (six cycles) and great stability (two months) in enriching N-linked glycopeptides and phosphopeptides from tryptic digests of standard proteins by combining HILIC and IMAC. Moreover, it was applied into the enrichment of endogenous N-linked glycopeptides and phosphopeptides in human saliva and achieved great results (43 phosphopeptides and 39 N-linked glycopeptides), revealing its promising potential in enrichment of low-abundance endogenous N-linked glycopeptides and phosphopeptides in practical samples.