Magnetic mesoporous silica nanocomposites with binary metal oxides core-shell structure for the selective enrichment of endogenous phosphopeptides from human saliva.

Developing an effective strategy for endogenous phosphopeptides enrichment and separation is necessary in phosphopeptidomics analysis due to the serious inference caused by chaotic biological environment. In this work, a size-exclusive magnetic binary metal mesoporous nanocomposites were synthesized to capture phosphorylated peptides for mass spectrometry analysis. The novel Fe3O4@TiO2-ZrO2@mSiO2 nanocomposites possessed the merits of ordered mesoporous channels, superparamagnetism and the integration of dual affinity of Zr-O and Ti-O. Compared with single-metal centered nanocomposites (Fe3O4@TiO2@mSiO2 and Fe3O4@ZrO2@mSiO2), Fe3O4@TiO2-ZrO2@mSiO2 showing much enhanced enrichment performance towards mono- and multi-phospho-peptides with better sensitivity. With all the advances, the Fe3O4@TiO2-ZrO2@mSiO2 was also successfully applied to capture endogenous phosphorylated peptides from human saliva. And consequently, a total of 30 phosphopeptides containing 2 multi- and 28 mono-phosphopeptides were identified efficiently. These results show that the novel materials have the great potential in peptidome analysis.