Nanoparticulate NaA zeolite composites for MRI: Effect of iron oxide content on image contrast

Highlights: • Fe₃O₄/NaA nanocomposites with various amounts of Fe₃O₄ were synthesized. • Effect of nano iron oxide content on MRI image contrast was studied. • By increasing iron oxide content, the nanocomposites relaxivities were decreased. • Aggregation of nano Fe₃O₄ is a limiting factor for using of the high iron oxide content nanocomposites. In the current study, Fe₃O₄/NaA nanocomposites with various amounts of Fe₃O₄ (3.4, 6.8 & 10.2 wt%) were synthesized and characterized to study the effect of nano iron oxide content on the magnetic resonance (MR) image contrast. The cell viability of the nanocomposites was investigated by MTT assay method. T2 values as well as r2 relaxivities were determined with a 1.5 T MRI scanner. The results of the MTT assay confirmed the nanocomposites cytocompatibility up to 6.8% of the iron oxide content. Although the magnetization saturations and susceptibility values of the nanocomposites were increased as a function of the iron oxide content, their relaxivity was decreased from 921.78 mM⁻¹ s⁻¹ for the nanocomposite with the lowest iron oxide content to 380.16 mM⁻¹ s⁻¹ for the highest one. Therefore, Fe₃O₄/NaA nanocomposite with 3.4% iron oxide content led to the best MR image contrast. Nano iron oxide content and dispersion in the nanocomposites structure have important role in the nanocomposite r2 relaxivity and the MR image contrast. Aggregation of the iron oxide nanoparticles is a limiting factor in using of the high iron oxide content nanocomposites.