A complementary bimetal synergized with polyethyleneimine functionalized affinity chromatography nanosphere for enrichment of global phosphopeptides

A novel metal-organic framework (MOF) synergized with Polyethyleneimine (PEI) functionalized hydrophilic magnetic nanosphere with two kinds of biological friendly metal ions (Fe 3 O 4 @PDA@MIL(Ti)-PEI-Nb) was fabricated and synthesized to enrich global phosphopeptides in complex biological samples. Based on the preference of Ti 4+ towards mono-phosphopeptides and the preference of Nb 5+ towards multi-phosphopeptides as well as the strong cationic charge density environment created by the high protonation of branched-PEI in acidic solution, the material performed prominently in the phosphopeptides enrichment, both in the standard protein for simulation and the three typical practical biological samples. The obtained material exhibits extremely high sensitivity (0.1 fmol), good selectivity (molar ratio of β-casein: BSA=1:5000), and excellent enrichment ability such as capturing 34 phosphopeptides from saliva. The combination of the comprehensive enrichment performance and biocompatibility presents a broad application prospect in phosphorylated proteomics.