Semi-Biosynthesis of Magnetite-Gold Composite Nanoparticles Using an Ethanol Extract ofEucalyptus camaldulensisand Study of the Surface Chemistry

Abstract

Green synthesis of metal nanoparticles, such as silver or gold nanoparticles, has been attracting increasing attention in recent years. Functionalized magnetite nanoparticles have many uses in various applications, including nanoelectronic devices, molecular recognition, biomedical applications, drug delivery targeting, and optical devices. In this investigation, magnetic cores (Fe3O4) were synthesized using a fabrication method involving coprecipitation ofFe2+andFe3+. In the next step, magnetite-gold composite nanoparticles were synthesized with size ranging from 6–20 nm, using an ethanol extract ofEucalyptus camaldulensisas a natural reducing agent. Transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction spectroscopy, and visible absorption spectroscopy confirmed the fabrication of magnetite-gold composite nanoparticles. In the UV spectra diagram, a red-shift of the surface plasmon of the Au was evidence that contact between gold andFe3O4had occurred. The surface chemistry of the as-prepared magnetite-gold nanoparticles was studied using infrared spectroscopy. The presence of organic compounds with a carboxyl moiety was confirmed on the surface of the magnetite-gold nanoparticles fabricated by this combined chemical and biological reducing process, which we have designated as a semi-biosynthesis method.