Magnetic ressonance imaging contrast agents obtained by fast sonochemistry approach

Abstract

Functionalized Fe3O4 nanoparticles (NPs) have emerged as a promising contrast agent for magnetic resonance imaging (MRI). Their synthesis and functionalization methodology strongly affects their performance in vivo. Although thermal decomposition is the most commonly used growth methodology reported in the literature, it has proven to be time-consuming, expensive, and laborious. Therefore, this work describes a rapid and facile sonochemical methodology to synthesize and functionalize Fe3O4 NPs with excellent physico-chemical properties for MRI. In this work, a sonochemistry approach was used to produce, in 12 min, Fe3O4 NPs functionalized with polysodium acrylate (PAANa), trisodium citrate (CIT), branched polyethylenimine (BPEI), and sodium oleate. X-ray diffraction and transmission electron microscopy demonstrated that the NPs were composed of a single inverse spinel phase with an average diameter of 9–11 nm and a narrow size distribution. It was confirmed by Mössbauer spectroscopy and magnetic measurements that the obtained NPs were transitioning to the superparamagnetic regime and possessed excellent magnetization saturation values (59–77 emu/g). Fourier transform infrared spectroscopy proved that the sonochemistry approach provided conditions that induced a strong interaction between Fe3O4 and the capping agents. Furthermore, dynamic light scattering experiments evidenced that samples coated with PAANa, CIT, and BPEI possess colloidal stability in aqueous solvents. Emphasis must be placed on PAANa-coated NPs, which also presented remarkable colloidal stability under simulated physiological conditions. Finally, the obtained NPs exhibited great potential to be applied as an MRI contrast agent. The transverse relaxativity values of the NPs synthesized in this work (277–439 mM-1s-1) were greater than those of commercial NPs and those prepared using other methodologies. Therefore, this work represents significant progress in the preparation of Fe3O4 NPs, providing a method to prepare high-quality materials in a rapid, cost-effective, and facile manner.