Tailoring a multifunctional magnetic cationic metal-organic framework composite for synchronous enrichment of phosphopeptides/glycopeptides

Herein, for the first time, a multifunctional magnetic cationic MOF composite (Fe3O4@ILI-01@Ti4+) was successfully prepared for the synchronous enrichment of phosphopeptides/glycopeptides. The as-prepared Fe3O4@ILI-01@Ti4+ bears attractive properties like abundant surface positive charge and excellent hydrophilicity, ensuring that phosphopeptides/glycopeptides can be well captured based on electrostatic attraction and hydrophilic interaction. By integrating Fe3O4@ILI-01@Ti4+ and mass spectrometry (MS) determination, high sensitivity (0.5 fmol for beta-casein and 0.1 fmol for HRP), excellent selectivity (1 : 5000 for beta-casein : BSA and 1 : 500 for HRP : BSA, mass ratio), and high recyclability (5 cycles) were achieved. In addition, Fe3O4@ILI-01@Ti4+ exhibits superior enrichment performance on synchronous enrichment of phosphopeptides/glycopeptides from beta-casein/HRP tryptic digests. Further applying it to actual samples like human serum and saliva, phosphopeptides and glycopeptides with high intensity were identified, indicating that Fe3O4@ILI-01@Ti4+ possesses great practical application value in synchronous enrichment of phosphopeptides/glycopeptides. This work offers a new channel for the application of MOFs in phosphoproteomics/glycoproteomics.