Dendritic Mesoporous Silica Nanoparticles with Abundant Ti⁴⁺ for Phosphopeptide Enrichment from Cancer Cells with 96% Specificity

Selective enrichment and sensitive detection of phosphopeptides are of great significance in many bioapplications. In this work, dendritic mesoporous silica nanoparticles modified with polydopamine and chelated Ti⁴⁺ (denoted DMSNs@PDA-Ti⁴⁺) were developed to improve the enrichment selectivity of phosphopeptides. The unique central-radial pore structures endowed DMSNs@PDA-Ti⁴⁺ with a high surface area (362 m² g^-1), a large pore volume (1.37 cm³ g^-1), and a high amount of chelated Ti⁴⁺ (75 μg mg^-1). Compared with conventional mesoporous silica-based materials with the same functionalization (denoted mSiO₂@PDA-Ti⁴⁺) and commercial TiO₂, DMSNs@PDA-Ti⁴⁺ showed better selectivity and a lower detection limit (0.2 fmol/μL). Moreover, 2422 unique phosphopeptides were identified from HeLa cell extracts with a high specificity (>95%) enabled by DMSNs@PDA-Ti⁴⁺, better than those in previous reports.