Highly Selective Enrichment of N‑Linked Glycan by Carbon-Functionalized Ordered Graphene/Mesoporous Silica Composites

Abnormal protein glycosylation has been demonstrated to be associated with many diseases; therefore, it is very important to conduct a comprehensive structure analysis of glycan for prognosis and diagnosis of diseases, such as cancer. In this work, for the first time, carbon-functionalized ordered graphene/mesoporous silica composites (denoted as C-graphene@mSiO₂) with large surface area and uniform pore size were designed and synthesized. By taking advantage of the special interaction between the carbon and glycans as well as size-exclusion ability, 25 N-linked glycans released from ovalbumin were observed clearly with strong MS signals and increased signal-to-noise (S/N) ratio. In addition, after enrichment with the C-graphene@mSiO₂ composites, 48 N-linked glycans (S/N > 10) with sufficient peak intensities were obtained from only 400 nL of healthy pristine human serum. The facile and low-cost synthesis method as well as high selective enrichment ability of the novel C-graphene@mSiO₂ composite makes it a promising tool for glycosylation research

Magnetic Binary Metal–Organic Framework As a Novel Affinity Probe for Highly Selective Capture of Endogenous Phosphopeptides

Highly efficient detection of endogenous phosphopeptides from complex biosamples is essential in phosphopeptidomics analysis due to the severe disturbance caused by the chaotic biological environment. In this study, for highly selective capture of endogenous phosphopeptides, a magnetic binary metal–organic framework (MOF) with Zr–O and Ti–O centers (denoted as Fe₃O₄@PDA@Zr-Ti-MOF) was designed and synthesized by a facile postsynthetic method. Briefly, Zr-based MOF was first coated on the surface of magnetic Fe₃O₄ with polydopamine (PDA) as a linker, and then, the as-prepared Fe₃O₄@PDA@Zr-MOF was exposed to DMF solution containing TiCl₄(THF)₂, resulting in the successful synthesis of Fe₃O₄@PDA@Zr-Ti-MOF. This newly prepared Fe₃O₄@PDA@Zr-Ti-MOF owned the merits of large specific surface area, unique porous structure, and superparamagnetism as well as the enhanced dual affinities of Zr–O and Ti–O centers toward both endogenous mono-phospho-peptides and multi-phospho-peptides, showing highly improved performance with better selectivity and sensitivity compared to single-metal centered MOFs (Fe₃O₄@PDA@Zr-MOF, Fe₃O₄@PDA@Ti-MOF). The Fe₃O₄@PDA@Zr-Ti-MOF was also successfully applied to extract endogenous phosphopeptides in biological sample of human saliva. As a result, 34 mono-phosphorylated peptides and 10 multi-phosphorylated peptides were detected from merely 1 μL of pristine human saliva, confirming its bright prospects in phosphopeptidomics analysis