The aim of this bilateral project is gamma-radiolytic synthesis and detailed microstructural characterization of δ-FeOOH/Au composite magnetic nanoparticles (NPs), with special emphasis on characterization by transmission electron microscopy of atomic resolution, as well as examination of SERS activity of synthesized NPs.

Gold and magnetic iron oxides nanoparticles have a very wide application in numerous areas. Additional properties are achieved by synthesis of composite magnetic Fe-oxide/Au NP, i.e. magnetic core@Au shell NP. The superparamagnetic iron oxide (SPION) core gives special magnetic properties and allows attraction by a magnet, while gold gives unique optical properties and allows further functionalization of the NPs surface. This makes composite SPION/Au NPs very attractive for use in diagnostics, magnetic resonance imaging, tumor therapy with hyperthermia, drug and gene delivery, bioseparation and catalysis.

In this project, composite SPION/Au particles will be synthesized by gamma-radiolytic method in a ⁶⁰Co panoramic source at RBI. Synthesis by ionizing radiation is a relatively new, efficient and environmentally friendly method in which a homogeneous and almost instantaneous reduction occurs without the addition of toxic/carcinogenic reducing agents, which is often the case with classical synthesis methods. Particular attention will be paid to the synthesis of composite δ-FeOOH/Au NPs. δ-FeOOH (feroxyhyte) is rarely studied but it is very important because it is the only iron oxyhydroxide that is magnetic at room temperature, it has a large specific surface area, pronounced adsorption properties and very good magnetic properties like the well-studied Fe-oxides: magnetite and maghemite. Partial characterization of synthesized NP will be performed at RBI. Detailed microstructural characterization (morphological and phase analysis) will be performed at the Institute of Chemistry in Ljubljana, with one of the best analytical high-resolution transmission microscope. This will provide insight into the type of composite particles formed, the quality of the formed coating and help to elucidate the mechanism of radiation synthesis of these NPs. Additionally, the SERS activity of the obtained composite NPs will be examined using pyridine (Py), rhodamine 6G (R6G) and/or 4-mercaptobenzoic acid (4 MBA) reporter molecules.