title: Hydrophilic modification of silica-titania mesoporous materials as restricted-access matrix adsorbents for enrichment of phosphopeptides.
abstract: A new nano-scale restricted-access matrix (RAM) SiO₂ (MCM-41) with relatively high Ti-content (Ti/Si=0.1), but superior surface area (1129 m²/g), was successfully synthesised for the enrichment of phosphopeptides. The TiO₂ was incorporated into the Si-MCM-41 via a hydrothermal process and the external surface was modified with alkyl diol by the successive hydrolysis of γ-(glycidyloxypropyl) trimethoxysilane (GPTMS). Scanning electron microscopy, transmission electron microscopy, N₂ adsorption and Fourier transform infrared spectroscopy were used to characterise the alkyl diol-Ti-MCM-41. The appropriate pore diameter (2 nm) coupled to the marshy weeds-like hydrophilic external surface result in an efficient size-exclusion effect for the adsorption of standard cytochrome c with a molecular weight (MW) of ca. 12.4 kDa. At the same time, the strong affinity interaction between the incorporated titanium in the framework and the phosphoryl groups of phosphopeptides demonstrated a selective extract of phosphopeptides from the tryptic digestion. The detection sensitivity for phosphopeptides, determined by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) was as low as 5 fmol for standard tryptic digest of β-casein. Therefore, this alkyl diol-Ti-MCM-41 mesoporous material can be used as a potential adsorbent for applications in MS-based phosphoproteomics.
authors.affiliation: Research Center for Analytical Sciences, Nankai University, Tianjin 300071, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Guan
authors.forename: Sen
authors.initials: S
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Xia
mesh_terms: D000327:Adsorption; D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity / Q000295:instrumentation* / Q000379:methods; D057927:Hydrophobic and Hydrophilic Interactions; D010446:Peptide Fragments / Q000032:analysis / Q000302:isolation & purification; D010748:Phosphopeptides / Q000032:analysis / Q000302:isolation & purification*; D016062:Porosity; D012680:Sensitivity and Specificity; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014025:Titanium / Q000737:chemistry*; D014357:Trypsin / Q000737:chemistry
chemical_list: D010446:Peptide Fragments; D010748:Phosphopeptides; D012821:Silanes; C039462:gamma-glycidoxypropyltrimethoxysilane; D012822:Silicon Dioxide; D014025:Titanium; D014357:Trypsin