Synthesis of Boronic Acid-Functionalized Core-Shell Mesoporous Silica-TiO₂ Nanocomposite for Specific Enrichment of...

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-TiO₂ 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 m² 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.