Synthesis of Boronic Acid‐Functionalized Core–Shell Mesoporous Silica–TiO2 Nanocomposite for Specific Enrichment of Glycopeptides From Biological Samples

Abstract Protein N‐glycosylation plays a pivotal role in regulating biological processes and is closely associated with various disease pathologies. However, the identification of N‐glycopeptides typically requires efficient enrichment and advanced mass spectrometric methods due to their low abundance and interference from non‐glycosylated peptides. Herein, a boronic acid‐functionalized core–shell mesoporous silica–TiO 2 nanocomposite is proposed for selective enrichment of N‐glycopeptides from biological samples. The material holds attractive merits, including hydrophilic interaction from silica, high BET surface area (122.8 m 2 g −1 ), large porosity (pore size: 8.5 nm), and boronic acid functionality, enabling efficient and specific glycopeptide capture. The enrichment performance using the synthesized material is demonstrated using tryptic digests of human immunoglobulin G (IgG), achieving high binding capacity (25 mg g −1 ), good repeatability, and selectivity (1:100) toward glycopeptides. A considerable number of N‐glycopeptides ( n = 35) are successfully enriched from a 5 µg IgG digest, and the detection sensitivity is evaluated to be as low as 33.3 fmol µL −1 . Finally, the approach is validated using N‐glycopeptides from human serum digest. From merely 2 µL of serum, 215 glycopeptides corresponding to 91 glycoproteins are enriched and identified by nano‐LC‐MS/MS, demonstrating the promising potential of the synthesized material in glycoproteomics research.