Modified Carbon Nanotubes Decorated with ZIFs as New Immobilized Metal Ion Affinity Chromatography Platform for Enrichment of Phosphopeptides

Abstract ZIF‐8, as one of the most representative zeolite imidazolate frameworks, is rarely used for the enrichment of phosphopeptides due to its dissolution in acid solution. By introducing branched‐chain polyethyleneimine (PEI), we have overcome the acid‐intolerance shortcoming of ZIF‐8 and applied it for phosphopeptides enrichment. A material with magnetic carbon nanotube (mCNT) as substrate, polydopamine (PDA) as hydrophilic interlayer and PEI‐ZIF‐8 as functional groups (denoted as mCNT@PDA@PEI‐ZIF‐8) was prepared through a facile method. The obtained material exhibited excellent performance on phosphopeptides enrichment, including high sensitivity (0.5 fmol), outstanding selectivity (molar ratio of β‐casein: BSA=1 : 2000), reusability of at least 6 times and so on. The enrichment performance on complicated biological samples was also remarkable, 20 phosphopeptides were successfully detected from human saliva and 4 phosphopeptides from human serum, exhibiting its great potential and bright prospects in phosphopeptides enrichment.