Biocompatible PMAO-coated Gd2O3/Fe3O4 composite nanoparticles as an effective T1–T2 dual-mode contrast agent for magnetic resonance imaging†

Abstract

In this study, we developed novel Gd₂O₃/Fe₃O₄ composite nanoparticles (GFO CNPs) via a simple one-step thermal decomposition of Fe(III) actylacetonate and Gd(III) acetate in octadecene solvent, with oleic acid (OA) and oleylamine (OM) serving as surfactants. The effects of the Gd/Fe molar ratio on the formation, size, and T₁, T₂ relaxation efficiency of the NPs were investigated. The as-synthesised GFO CNPs were characterised using various analytical techniques such as TEM, HRTEM, XRD, UV-Vis, VSM, EDX and XPS. The results showed that GFO CNPs synthesised at a Gd/Fe ratio of 7/3 (GFO-7/3 CNPs) had an average size of about 10 nm, exhibited monodispersity with a narrow size distribution, and demonstrated superparamagnetic properties at room temperature. Additionally, surface modification of the NPs with PMAO improved their dispersibility and stability in aqueous media. Cytotoxicity tests confirmed the biocompatibility of the PMAO encapsulated GFO CNPs. In vitro relaxivity studies showed high r₁ and r₂ values of 18.20 and 94.75 mM⁻¹ s⁻¹, respectively, with an r₂/r₁ ratio of 5.21, outperforming commercial products such as Feraheme, Resovist, Feridex, and Dotarem. These findings suggest that GFO CNPs provide a promising nanoplatform for non-invasive T₁–T₂ dual-modality MRI diagnosis.