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 m(2) g(-1)), a large pore volume (1.37 cm(3) g(-1)), and a high amount of chelated Ti4+ (75 mu g mg(-1)). Compared with conventional mesoporous silica-based materials with the same functionalization (denoted mSiO(2)@PDA-Ti4+) and commercial TiO2, DMSNs@PDA-Ti4+ showed better selectivity and a lower detection limit (0.2 fmol/mu L). 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.