Separation of the defect-free Fe3O4-Au core/shell fraction from magnetite-gold composite nanoparticles by an acid wash treatment

Some undesired nanoparticles, such as malformed structures or incomplete core/shell Fe3O4-Au nanocomposites, might be formed when Fe3O4-Au core/shell nanocomposites are being synthesized. These impurities should be separated before any applications are performed. In this investigation, magnetic cores (Fe3O4) were synthesized using a conventional fabrication method involving coprecipitation of Fe2+ and Fe3+. Carboxyl-capped magnetite-gold composite nanoparticles, measuring ≤50 nm, were then synthesized using a plant extract (Eucalyptus camaldulensis). The prepared carboxyl-capped magnetite-gold composite nanoparticles were further subjected to acid treatment for 18 h and characterized with different instrumentation methods. The results of the investigation showed that acid treatment can be applied successfully to separate defect-free Fe3O4-Au core/shell nanoparticles from different types of Fe3O4-Au nanocomposites, without any considerable changes in their physiochemical properties.