Amino Acid-Functionalized Two-Dimensional Hollow Cobalt Sulfide Nanoleaves for the Highly Selective Enrichment of N-Linked Glycopeptides.

Leaf-like hollow cobalt sulfides with a sulfur-gold-cysteine (S-Au-Cys) structure on the surface have been synthesized for efficient N-glycopeptide enrichment. A two-dimensional (2D) zeolitic imidazolate framework with cobalt (ZIF-L-Co, L for leaf) was used as a self-sacrificed template. After sulfidation, the S-Au-Cys architecture was created on the surface of the leaf-like hollow cobalt sulfide to obtain a material denoted ZIF-L-Co-S-Au-Cys. Enrichment of glycopeptides from trypsin digests of immunoglobulin G (IgG) standard samples and of IgG isolated from real human plasma samples was accomplished via hydrophilic interaction liquid chromatography processes using ZIF-L-Co-S-Au-Cys. The good sensitivity and selectivity ensure the effectiveness and robustness of ZIF-L-Co-S-Au-Cys for sample preconcentration, which is comparable to a commercial HILIC product. This work provides an efficient way to produce transition metal sulfides with a low-dimensional morphology and provides a novel concept for material design for exploitation in sample preparation, especially in glycoproteomics.