Synthesis and characterization of magneto-optical bifunctional Fe3O4/Gd2O3:Tb3+@SiOx nanocomposites for enhanced MR imaging

Abstract

Gadolinium- and iron-based contrast agents (CA) have historically been the most commonly utilized MR imaging CA. However, the potential toxicity of metallic substances presents an obvious drawback. In this paper, magneto-optical bifunctional Fe₃O₄/Gd₂O₃:Tb³⁺@SiOx nanocomposites were synthesized via co-precipitation and polyol method. The biocompatibility and dispersibility of Fe₃O₄/Gd₂O₃:Tb³⁺ were improved by covering the outer side with a layer of SiOx. The effects of various synthesis temperatures on the properties of the composites were investigated. It was found that with the increase of synthesis temperature, the average particle size of Fe₃O₄/Gd₂O₃:Tb³⁺@SiOx crystal increased from 15 to 23 nm and the saturation magnetization decreased from 13.734 to 10.623 emu/g. Higher luminescence and magnetic intensity are observed in the nanocomposites synthesized at 25 °C due to the enhanced crystallinity and size uniformity. Finally, in vitro cytotoxicity and in vivo MR images in SD mice demonstrated the excellent biocompatibility and high-resolution MR imaging of Fe₃O₄/Gd₂O₃:Tb³⁺@SiOx.