Binary magnetic metal-organic frameworks composites: a promising affinity probe for highly selective and rapid enrichment of mono- and multi-phosphopeptides

A binary magnetic metal-organic framework (MOF)-functionalized material (magG@PDA@Ni-MOF@Fe-MOF) was prepared through grafting Ni-MOF and Fe-MOF on magnetic (Fe3O4) graphene with polydopamine (PDA) as a middle layer. Compared with single MOFs functionalized materials (magG@PDA@Ni-MOF and magG@PDA@Fe-MOF) under the same conditions, magG@PDA@Ni-MOF@Fe-MOF not only displays lower detection limits (4 fmol) and selectivity (1:1000), but also has better enrichment efficiency for both multi- and monophosphopeptides. Other than this, magG@PDA@Ni-MOF@Fe-MOF exhibits fine reusability (five cycles) and rapid enrichment property (1 min), and 24 phosphopeptides were detected when it was applied to the analysis of human saliva.