The GO/rGO–Fe3O4 composites with good water-dispersibility and fast magnetic response for effective immobilization and enrichment of biomolecules

The graphene oxide (GO)–Fe3O4 and the reduced graphene oxide (rGO)–Fe3O4 composites with good water dispersibility, high affinity and rapid magnetic response have been prepared via a facile grafting method. They can be used for the effective immobilization of proteins and the enrichment of peptides, respectively. By taking advantage of the high loading capacity and the abundant hydrophilic groups of the GO–Fe3O4 composites, they can be applied to immobilize proteins. The amount of loading of protein (BSA) on GO–Fe3O4 is as high as 294.54 mg g−1. The rGO–Fe3O4 composites can be used to enrich the low-concentration peptides conveniently due to their high surface areas, special structures and strong magnetism. Nineteen target peptides with the sequence coverage of 21% can be enriched and detected from the highly diluted digest of BSA (5 fmol μL−1). These results reveal that the prepared GO/rGO–Fe3O4 composites have potential application as a carrier for biomolecule immobilization, enrichment, and separation.