Carnosine functionalized magnetic metal–organic framework nanocomposites for synergistic enrichment of phosphopeptides

Protein phosphorylation regulates the conformations and function of proteins, which plays an important part in organisms. However, systematic and in-depth analysis of phosphorylation often hinders on account of the low abundance and suppressed ionization of phosphopeptides. Various materials based on single enrichment mechanism show potential in phosphopeptides enrichment, but the enrichment performance is typically not satisfactory. Herein, we developed a carnosine (Car) functionalized magnetic metal organic framework designed as Fe 3 O 4 @NH 2 @ZIF-90@Car. Benefiting from the multiple recognition groups of Car and massive metal ions site of ZIF-90, the as-fabricated Fe 3 O 4 @NH 2 @ZIF-90@Car was utilized as a multifunctional material with synergistic effect for phosphopeptides enrichment. On the basis of combined immobilized metal ion affinity chromatography (IMAC) and amine-based affinity enrichment mechanism, Fe 3 O 4 @NH 2 @ZIF-90@Car exhibited higher enrichment performance of phosphopeptides compared with Fe 3 O 4 @NH 2 @ZIF-90 (single IMAC mechanism). Besides, the feasibility of Fe 3 O 4 @NH 2 @ZIF-90@Car nanocomposites in complicated samples was further verified by enriching phosphopeptides from nonfat milk, human fluids such as serum and saliva, demonstrating its bright application prospects in phosphoproteomics analysis.