Synthesis of Gold-Magnetite Magnetic Nanoparticles for Biomedical Applications

  • Mr Ian Goon, The University of New South Wales, School of Chemical Sciences and Engineering, Australia
  • Mr Leo Lai, The University of New South Wales, School of Chemistry, Australia
  • Dr May Lim, The University of New South Wales, School of Chemical Sciences and Engineering, Australia
  • Prof J Gooding, The University of New South Wales, School of Chemistry, Australia
  • Prof Rose Amal, The University of New South Wales, School of Chemical Sciences and Engineering, Australia

    • Objective:
    Gold coated magnetite nanoparticles have become the focus of much research due to the varied applications envisaged for the particles in biomedicine. Many studies have attempted to create functional magnetic gold coated particles but as yet, have not reported particles with the combined characteristics of size, stability, magnetism and purity for biomedical applicability. The synthesis of such particles serves as the objective of this paper.
    Methods:
    A novel, low energy, aqueous based method for synthesizing gold and silver metallic coatings on highly crystalline magnetite is reported herein. The stepwise method involves the functionalization of 30 nm magnetite particles with a polyelectrolyte, followed by the attachment of a dense layer of gold nanoparticle seeds on the magnetite surface, and the eventual development of a full gold shell.
    Results:
    Transmission electron microscope images were taken at each step to monitor the growth of a gold shell around the magnetite particles. SQUID magnetometry , UV-Visible spectroscopy and zeta-potential measurements to provide evidence of composite structure and biomedical applicability. The procedure is simple, inexpensive and overcomes problems caused by the difference in the surface energies of gold and magnetite which previously prevented the formation of a uniform gold coating.
    Conclusions:
    This is the first report of a magnetite-gold core-shell nanoparticles with the combined characteristics of controlled size, stability, complete coating, high magnetic susceptibility and purity for biomedical applicability. The low energy aqueous based procedure opens up exciting avenues for further development and applications of such core-shell nanostructures.