In Situ MXene-Controlled Synthesis of Polycrystalline TiO2 for Highly Efficient Enrichment of Phosphopeptides

Phosphopeptide enrichment methods based on commercial TiO2 suffer from difficulties in regulating intermolecular interactions, resulting in low coverage rate and the loss of information on multiphosphorylation sites, thereby limiting comprehensive phosphoproteomic analysis. In this work, MXene Ti3C2Tx was incorporated into the design of enrichment materials, with its surface structure functionalized and regulated to address the low elution efficiency of TiO2 for multiphosphorylated peptides. Upon oxidation treatment, the Ti3C2Tx material formed numerous uniformly distributed TiO2 nanoparticles on the surface of Ti3C2Tx-O, providing abundant affinity sites (Ti–O) for selective phosphopeptide enrichment. The polycrystalline structure and rich oxygen vacancies of the material effectively regulated its binding affinity with phosphate groups, achieving simultaneous high-efficiency enrichment of both monophosphorylated and multiphosphorylated peptides. Its performance was significantly superior to that of commercial TiO2 and IMAC materials. This study presents great promise for the practical application of comprehensive phosphoproteomic analysis in the future and broadens the application of MXene in the biological field.