Highly monodisperse low-magnetization magnetite nanocubes as simultaneous T₁–T₂ MRI contrast agents

Abstract

We report the first study of highly monodisperse and crystalline iron oxide nanocubes with sub-nm controlled size distribution (9.7 ± 0.5 nm in size) that achieve simultaneous contrast enhancement in both T1- and T2-weighted magnetic resonance imaging (MRI). Here, we confirmed the magnetite structure of iron oxide nanocubes by X-ray diffraction (XRD), selected area electron diffraction (SAED) pattern, optical absorption and Fourier transformed infrared (FT-IR) spectra. These magnetite nanocubes exhibit superparamagnetic and paramagnetic behavior simultaneously by virtue of their finely controlled shape and size. The magnetic measurements reveal that the magnetic moment values are favorably much lower because of the small size and cubic shape of the nanoparticles, which results in an enhanced spin canting effect. As a proof-of-concept demonstration, we showed their potential as dual contrast agents for both T1- and T2-weighted MRI via phantom studies, in vivo imaging and relaxivity measurements. Therefore, these low-magnetization magnetite nanocubes, while being non-toxic and bio-compatible, hold great promise as excellent dual-mode T1 and T2 contrast agents for MRI.

Fe3O4@NiFexOy Nanoparticles with Enhanced Electrocatalytic Properties for Oxygen Evolution in Carbonate Electrolyte

“…We followed and detail here a procedure developed from merging two previously reported protocols. 56,57 First, iron oleate (Fe-OA) was obtained by dissolving 1. Structural, Chemical, and Magnetic Characterization.…”

“…Following previous reports, we indexed it as magnetite (JCPDS 01-086-1350). 56,57 The peak broadening due to the small crystal domain size and the very similar unit cell parameters of Fe (Figure 3a). Elemental compositional maps, obtained by EELS using O K, Fe L 2,3 , and Ni L 2,3 edges, revealed the presence of Fe and O throughout all the cubic-shaped NPs, but with a 3% increase in oxygen content and 6% reduction in Fe atomic percent at the outer parts of the NP with respect to the center.…”

Artificial local magnetic field inhomogeneity enhances T2 relaxivity

“…To pursue high-performance MRI contrast agents, the outersphere motional averaging regime (MAR) theory has been applied to guide the rational engineering of MNPs1011. In short, MAR theory illustrates that T 2 contrast efficiency ( r 2 ) is related to the diffusion of surrounding water protons and the physical properties of MNPs, which can be tuned by their size1213, shape1415161718, component192021, crystal structure2223 and surface property2425.…”

<p>A Radio-Nano-Platform for T1/T2 Dual-Mode PET-MR Imaging</p>

“…Therefore, the development of T1/T2 dual modal contrast agents has recently attracted much attention. [30][31][32][33] Clinically, T1, brighter images are preferred for better resolution and easy detection. 29 However, T2 images are useful for examining inflamed areas or fluid-rich structures.…”