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 Ti 4+ (denoted DMSNs@PDA-Ti 4+ ) were developed to improve the enrichment selectivity of phosphopeptides. The unique central-radial pore structures endowed DMSNs@PDA-Ti 4+ with a high surface area (362 m 2 g –1 ), a large pore volume (1.37 cm 3 g –1 ), and a high amount of chelated Ti 4+ (75 μg mg –1 ). Compared with conventional mesoporous silica-based materials with the same functionalization (denoted mSiO 2 @PDA-Ti 4+ ) and commercial TiO 2, DMSNs@PDA-Ti 4+ 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-Ti 4+, better than those in previous reports.