Hydrophilic maltose-modified magnetic metal-organic framework for highly efficient enrichment of N-linked glycopeptides.

Biomedical sciences, and in particular disease biomarker research, demand highly selective and efficient glycoproteins/peptides enrichment platforms. In this work, a facile strategy to prepare hydrophilic maltose-functionalized magnetic metal-organic framework loaded with Au nanoparticles (denoted as magMOF@Au-maltose) for highly efficient enrichment of N-linked glycopeptides. In brief, carboxyl-functional Fe3O4 nanospheres were firstly coated with a Zr-based MOF shell, the resulting MOF was then loaded with Au nanoparticles in situ and then modified with thiol-functional maltose via Au-S bonds to obtain magMOF@Au-maltose with core-shell structure. The physical property and adsorption of magMOF@Au-maltose to glycopeptides were investigated. The results showed magMOF@Au-maltose possessing the outstanding performance in glycopeptides enrichment with high selectivity (1:200, mass ratio of horseradish peroxidase to bovine serum albumin digest), a low limit of detection (10 fmol), a high recovery (over 83.3%), and a large binding capacity (83 μg•mg-1). The magMOF@Au-maltose nanocomposite can enrich 24 and 32 glycopeptides from tryptic HRP and human IgG digests, respectively. Moreover, the nanocomposite was applied to the selective enrichment of glycopeptides from the complex biological samples and a total of 123 unique N-glycosylation sites were identified from 113 glycopeptides in 1 μL of human serum, which were assigned to 46 different glycoproteins. These results showed the promising application of magMOF@Au-maltose in the detection and identification of low-abundance N-linked glycopeptides in complex biological samples.