Fabrication of norepinephrine and ε-polylysine engineered magnetic nanocomposites tailored for phosphopeptides analysis.

Protein phosphorylation is a highly prevalent post-translational modification that holds a vital position in numerous physiological processes. Prior to mass spectrometry detection, the enrichment of phosphopeptides is critically significant due to their susceptibility to interference from abundant non-phosphopeptides. In this study, the magnetic nanocomposite (Fe₃O₄@NE@PL) was successfully synthesized and characterized. Fe₃O₄@NE@PL exhibited strong hydrophilicity, electrophilicity and intermolecular interactions through hydrogen bonds, enabling it to effectively enrich phosphopeptides with excellent sensitivity (0.4 fmol β-casein) and selectivity (β-casein:BSA=1:1000). In addition, Fe₃O₄@NE@PL was successfully applied to enrich phosphopeptides from complex real biological samples such as human serum and saliva, achieving up to 4 recycles with favorable stability and reusability. This study demonstrates that Fe₃O₄@NE@PL is a promising adsorbent for phosphopeptides enrichment in proteomics research, providing new ideas for the construction of magnetic enrichment materials.