Facile synthesis of Fe3O4@mesoporous TiO2 microspheres for selective enrichment of phosphopeptides for phosphoproteomics analysis.

Protein phosphorylation is one of the most important post-translational modifications. Due to the dynamic nature and low stoichiometry of the protein phosphorylation, enrichment of phosphopeptides from proteolytic mixtures is necessary prior to their characterization by mass spectrometry. In this work, we synthesized Fe3O4@mesoporous TiO2 magnetic microspheres with core-shell structure and large surface area for selective enrichment of phosphopeptides. To demonstrate its ability for selective enrichment of phosphopeptides, we applied Fe3O4@mesoporous TiO2 magnetic microspheres to isolation and enrichment of the phosphopeptides from tryptic digestion of standard proteins and real samples, and then the enriched peptides were analyzed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) or liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS). Due to that the as-made Fe3O4@mesoporous TiO2 microspheres have large surface area, good dispersivity and biocompatibility, they have been demonstrated as a powerful tool for phosphoproteomics research.