The effect of polymer and gold functionalization on the magnetic properties of magnetite nanoparticles

Silica coated magnetite particles (Fe3O4@SiO2) functionalized with gold Fe3O4@SiO2 + Au), or gold plus poly (vinylpyrrolidone) (PVP) (Fe3O4@SiO2 + Au + PVP) were synthesized. Their structural and magnetic properties were studied using a combination of experimental techniques including electron microscopy (EM), superconducting quantum interference device (SQUID) magnetrometry, and electron paramagnetic resonance (EPR) spectroscopy. The saturation magnetization (MS) of particles functionalized with gold and gold plus PVP were found to be 67.24 emu/g and 65.78 emu/g respectively. Both functionalized ensembles maintained a large percentage (78-80%) of their MS values compared to pristine magnetite. The coercivity (HC) for pristine magnetite was 227.25 Gauss compared to 200.00 Gauss for Fe3O4@SiO2 + Au and 228.57 Gauss for Fe3O4@SiO2 + Au + PVP. Furthermore, these magnetic particles, being biologically compatible and resistant to oxidation, were functionalized with an antibody designed to target A431 oral cancer cells. The result demonstrates high specificity of binding compared to non-functionalized particles, attributable to a favorable interaction between gold and the antibody making them excellent candidates for applications like bio-separation and imaging.