In Situ Controllable Fabrication of Two-Dimensional Magnetic Fe3O4/TiO2@Ti3C2Tx Composites for Highly Efficient Phosphopeptides Enrichment

Highly efficient enrichment of phosphopeptides is of great significance for phosphoproteomics-related biological and pathological processes research, but it remains challenging due to the lack of affinity materials which hold high enrichment efficiency and capacity. Ti3C2Tx MXene, a novel two-dimensional material with outstanding physicochemical properties, has attracted wide research interests for application in various fields. However, there are few reports on the use of MXene-derived materials for phosphopeptides separation in the biomedical field. In this work, we proposed a facile one-pot method that in situ oxidation and modification of Ti3C2Tx MXene, to prepare two-dimensional (2D) magnetic Fe3O4/TiO2@Ti3C2Tx composites for potential application in phosphopeptides enrichment. Benefiting from the outstanding magnetic responsiveness and multiaffinity sites (Ti–O, Fe–O, and NH2 groups), the Fe3O4/TiO2@Ti3C2Tx composites possessed excellent enrichment performance with high sensitivity (0.1 fmol μL–1), excellent selectivity (β-casein: bovine serum albumin = 1:5000, molar ratio), good repeatability (5 times), and high enrichment capacity (200 mg g–1). Moreover, the results of selective enrichment of phosphopeptides from nonfat milk, human saliva, human serum, and rat brain lysates indicated the great potential of Fe3O4/TiO2@Ti3C2Tx composites in low-abundance phosphopeptides enrichment from complex biological samples. This work has put forward a versatile method to prepare magnetic MXene composites and promoted the use of MXene composites in phosphoproteome in biomedicine.