Abstract
High magnetisation and monodisperse CoFe alloy nanoparticles are desired for a wide range of biomedical applications. However, these CoFe nanoparticles are prone to oxidation, resulting in the deterioration of their magnetic properties. In the current work, CoFe alloy nanoparticles were prepared by thermal decomposition of cobalt and iron carbonyls in organic solvents at high temperatures. Using a seeded growth method, we successfully synthesised chemically stable CoFe@Pt core/shell nanostructures. The obtained core/shell nanoparticles have high saturation magnetisation up to 135 emu g-1. The magnetisation value of the core/shell nanoparticles remains 93 emu g-1 after being exposed to air for 12 weeks. Hydrophobic CoFe@Pt nanoparticles were rendered water-dispersible by encapsulating with poly(maleic anhydride-alt-1-octadecene) (PMAO). These nanoparticles were stable in water for at least 3 months and in a wide range of pH from 2 to 11.
Highlights
The magnetic nanoparticles have attracted a great deal of attention due to their wide range of potential applications
CoFe alloy nanoparticles were synthesised by simultaneous thermal decomposition of cobalt and iron carbonyls in organic solvents in the presence of oleic acid (OA) and OLA as stabilising agents
Monodisperse CoFe@Pt core/shell nanoparticles have been successfully prepared in organic solvents
Summary
The CoFe alloy nanoparticles can be coated with an additional inorganic layer to form core/shell nanostructures. The syntheses of monodisperse and high saturation magnetisation of CoFe and CoFe@Pt core/shell nanoparticles in organic solvents are described. The synthesised CoFe@Pt nanoparticles exhibited tunable magnetic properties with a saturation magnetisation value as high as 135 emu g−1. The saturation magnetisation value of the core/shell nanoparticles remains 93 emu g−1 after being exposed to air for several months. The hydrophobic core/shell nanoparticles were transferred into water by encapsulation with poly(maleic anhydride-alt-1-octadecene) (PMAO). The obtained platinum coated CoFe nanoparticles show a promising potential for biomedical applications, such as in hyperthermia cancer treatment, MRI or in surface enhanced Raman scattering (SERS) sensing applications
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