Magnetic and optical properties of gold coated iron oxide nanoparticles

Magnetic nanoparticles (MNPs) are in branch of interest due to their unique magnetic properties, which have potential in applications, for example in biomedicine [1]. Among magnetic materials, iron oxide MNPs are most... [ view full abstract ]

Magnetic nanoparticles (MNPs) are in branch of interest due to their unique magnetic properties, which have potential in applications, for example in biomedicine [1]. Among magnetic materials, iron oxide MNPs are most promising because of the magnetization saturation high value and moderate cytotoxicity effect on human cells. However, they are difficult to functionalize and with prolonged exposure to the body they produce free radicals. To overcome these limitations, the MNPs can be covered with some materials as polymers, oxides, and metals forming core/shell structures. Fe₃O₄/Au MNPs are the most commonly used due to the possibility of bioconjugation and good biocompatibility [2]. Moreover, when gold-covered, some new optical functions to MNPs occur, in particular, to combine the both therapy and diagnostic agency in single vehicle [3]. In this work the core of iron oxide was prepared with co-precipitation route and shell of gold was build up by reduction of AuCl⁴⁻ on the surface of cores to assemble Fe₃O₄/Au core/shell structure in form of electrostatic stabilized suspension as reported earlier [4]. Hydrodynamic radius expected from photon correlation spectroscopy (PCS) method was 17±2 nm for naked iron oxide and 26±6 nm for gold-coated MNPs. In order to distinguish the impact of the gold shell, the UV-Vis and Raman spectroscopy techniques were performed for naked and gold-coated MNPs. Magnetic properties were studied with SQUID magnetometer and superparamagnetic state of MNPs at room temperature was confirmed for both systems.

The reported study was funded by RFBR according to the research project № 17-32-50202.

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[2] Salihov, S.V., et al. J. Magn. Mag. Mat. 394. 173-178 (2015)

[3] Vinhas, R., et al. Nanobiosensors Dis. Diagnosis. Doi:10.2147/NDD.S60285 (2015)

[4] Majouga, A., et al. Colloids Surf. B Biointerfaces. 125. 104-109 (2015)