Application of polyoxometalate-based metal-organic framework modified magnetic black phosphorus nanosheets for phosphoproteome analysis.

In this work, polyoxometalate-based metal-organic framework modified magnetic black phosphorus nanosheets (Fe3O4/BPNSs/POMOF) were designed and constructed. The resulting composite exhibited high surface area, excellent hydrophilicity, and superparamagnetism. Fe3O4/BPNSs/POMOF combined the Fe-O groups of Fe3O4, the metal oxide clusters of polyoxometalate, and rich Zn2+ ions along with inherent porosity of MOF. Fe3O4/BPNSs/POMOF was employed as a magnetic solid-phase extraction adsorbent for highly efficient phosphopeptide enrichment prior to mass spectrometry analysis. By integrating the principles of immobilized metal ion affinity chromatography and metal oxide affinity chromatography, Fe3O4/BPNSs/POMOF achieved high selectivity, enabling phosphopeptide capture even with a 5000-fold excess of competing peptides. The material had good recyclability (10 cycles) and high recovery (90.7 %) for phosphopeptides. The material maintained efficient enrichment capability for complex biological samples such as A549 cell lysate, highlighting its practical utility in phosphoproteomic research.