▎ 摘　　要

Developing an efficient strategy to enrich the low abundance phosphopeptides before mass spectrometry detection is a vital preprocessing step in phosphoproteomics. In this work, we synthesized an adenosine phosphate-Ti4+ functionalized magnetic mesoporous graphene oxide nanocomposite (denoted as MG@ mSiO(2)-ATP-Ti4+) to selectively extract phosphorylated peptides from complex biological samples based on the immobilized metal ion affinity chromatography (IMAC). Mesoporous silica was coated on the substrate material of magnetic graphene oxide and then the ATP containing three phosphate groups was grafted on the inwall of mesoporous channels as chelating ligands to immobilize the Ti4+ cations. With favorable properties, such as large surface area and good hydrophilicity and size-exclusion effect, the MG@mSiO(2)-ATP-Ti4+ exhibited excellent sensitivity and selectivity toward phosphopeptides whether in low concentration of beta-casein digest (20 amol mu L-1, 4 fmol) or the digest mixture of beta-casein and bovine serum albumin (with molar ratio of 1:1000) as well as good reusability. Furthermore, MG@mSiO(2)-ATP-Ti4+ could also be applied in the selective enrichment of phosphorylated peptides from nonfat milk digest and human saliva and serum.