Preparation and MRI performance of a composite contrast agent based on palygorskite pores and channels binding effect to prolong the residence time of water molecules on gadolinium ions

Facile synthesis of water-soluble Fe3O4 and Fe3O4@PVA nanoparticles for dual-contrast T1- and T2-weighted magnetic resonance imaging

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used as a robust negative contrast agent on conventional MRI. The development of new types of high-performance nanoparticulate MR contrast agents with either positive (T1) or dual-contrast (both positive and negative, T1 + T2) ability is of great importance. Here we report a facile synthesis of Fe₃O₄ and Fe₃O₄@PVA nanoparticles for dual-contrast T1- and T2-weighted MRI. The produced iron oxide nanoparticles were of high crystallinity and size uniformity with an average diameter of 7.25 & 8.64 nm and can be individually dispersed in the physiological buffer with high stability. The functional compositions and formation of PVA-magnetite composite were confirmed by FTIR analysis. VSM studies have shown that magnetite and PVA-magnetite composite nanoparticles exhibit superparamagnetic behavior at room temperature with saturation magnetization value of 54.82 emu/g, 39.62 emu/g respectively. It's due to the presence of nonmagnetic PVA molecule on magnetite and decrease in the size of the magnetite. The XPS and Mössbauer spectra reveals presence of pure Fe₃O₄ nanoparticles. In-vitro relaxivity and contrast enhancement analysis show that, among both tested nanoparticles, Fe₃O₄@PVA nanoparticles possess optimal molar relaxivities and contrast enhancement values, which can shorten the spin-lattice and spin-spin relaxation times, simultaneously.