Highly efficient enrichment of phosphopeptides by a magnetic lanthanide metal-organic framework

• A facile route for preparation of a magnetic lanthanide metal-organic framework (denoted as Fe3O4@PDA@Er(btc)).
• Strong magnetic responsiveness, excellent hydrophilicity, high selectivity and sensitivity for phosphopeptide enrichment.
• Stable and reusable for several times.

Highly efficient enrichment of phosphopeptides from complex biological samples is crucial prior to mass spectrometry analysis due to the low abundance and ion suppression effects. In this study, a facile route was designed for preparation of a magnetic erbium(Er)-based metal-organic framework (denoted as Fe3O4@PDA@Er(btc)), which was synthesized with 1,3,5-benzenetricarboxylic acid(H3btc) as ligand and grafted on the polydopamine (PDA) – coated Fe3O4. The as-prepared material exhibited ultra-high sensitivity (detection limit of 20 amol/μL) and selectivity at a low mass ratio of β-Casein/BSA (1:500). Moreover, it was also investigated for enrichment of phosphopeptides from human serum, which provided a promising technique for highly efficient enrichment of low-abundance phosphorylated peptides in the practical application.