Facile methods for synthesis of core-shell structured and heterostructured Fe3O4@Au nanocomposites

► Core-shell structured and heterostructured Fe3O4@Au nanocomposites are synthesized. ► Both structures are aiming at diverse applications. ► The polyethylenimine coated Fe3O4 nanoparticles were used as seeds. ► Both structures combined the merits of both gold and Fe3O4 nanoparticles. ► The methods suggested new ways for synthesizing multifunctional nanostructures.