Cysteine-functionalized metal-organic framework (MOF) was synthesized via a common and facile two-step method of in situ loading of Au nanoparticles on amino-derived MOF followed by l-cysteine (Cys) immobilization. Owing to the large specific surface area and ultrahigh hydrophilicity of this nanocomposite, excellent performance was observed in the enrichment of N-linked glycopeptides in both model glycoprotein and HeLa cell lysate. By using this nanocomposite, 16 and 31 glycopeptides were efficiently extracted from digest of horseradish peroxidase (HRP) and human serum immunoglobulin G (IgG), respectively. The short incubation time (5 min), large binding capacity (150 mg/g, IgG digest to material), good selectivity (1:50, molar ratio of IgG and bovine serum albumin (BSA) digest), high recovery (over 80%), and low detection limit (1 fmol) ensure the effectiveness and robustness of MIL-101(NH)@Au-Cys in complex HeLa cell lysate. As a result, 1123 N-glycosylation sites corresponding to 1069 N-glycopeptides and 614 N-glycoproteins were identified from the lysate. Compared with those of previously reported hydrophilic methods, to our knowledge, it was the best result. This work paves a new way for fast functionalization of MOF and also provides a novel idea for material design in sample preparation, especially in glycoproteome and related analysis.

A maltose-functionalized metal-organic framework (MOF), MIL-101(Cr)-maltose, was developed via a simple two step post-synthetic modification of MIL-101(Cr)-NH2. With the use of this nanomaterial, 33 glycopeptides were detected from the digest of human immunoglobulin G, demonstrating its high efficiency in glycoproteomic analysis. More importantly, the generic functionalization route from amino-derived MOFs opens a new perspective in material design in sample preparation.

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