Application of liquid phase deposited titania nanoparticles on silica spheres to phosphopeptide enrichment and high performance liquid chromatography packings

A novel core–shell composite (SiO2–nLPD), consisting of micrometer-sized silica spheres as a core and nanometer titania particles as a surface coating, was prepared by liquid phase deposition (LPD). Here, we show the resulting core–shell composite to have better efficient and selective enrichment for mono- and multi-phosphopeptides than commercially available TiO2 spheres without any enhancer. The material exhibited favorable characteristics for HPLC, which include narrow pore size distribution, high surface area and pore volume. We also show that the core–shell composite can efficiently separate adenosine phosphate compounds due to the Lewis acid–base interaction between titania and phosphate group when used as HPLC packings. After coating the silica sphere with titania by LPD, the silanol of silica spheres will be shielded and that the stationary phase, C18 bonded SiO2–3LPD, could be used under extreme pH condition.