Dual-Functionalized Magnetic Metal-Organic Framework for Highly Specific Enrichment of Phosphopeptides

The highly specific enrichment of phosphoproteins and phosphopeptides from intricate biological systems is the precondition of in-depth phosphoproteome research. Herein, a novel dual-functionalized magnetic zirconium-based metal-organic framework (MOF) denoted as DFMMOF, with the purpose of combining the affinity of immobilized metal ion affinity chromatography (IMAC) and metal oxide affinity chromatography (MOAC) has been successfully synthesized. The inherent Zr-O cluster of DFMMOF particles acted as MOAC and the immobilized titanium(IV) ions served for IMAC. The obtained DFMMOF exhibited rapid magnetic separation (within 5 s), large surface area (237.9 m(2) g(-1)), high binding capacity (100 mg g(-1)), and good postenrichment recovery (84.8%). Thanks to the strong affinity, low detection sensitivity (5 fmol) and high selectivity (beta-casein/BSA with a molar ratio of 1:1000) for phosphopeptide enrichment were obtained using DFMMOF as absorbent. Moreover, the effective identification of phosphopeptides from real samples (human serum and nonfat milk) further confirmed the immense potential of DFMMOF as a promising candidate for the detection and extraction of trace amounts of phosphorylated peptides in complex biosamples.