Iron Oxide Superparticles with Enhanced MRI Performance by Solution Phase Epitaxial Growth

Abstract

Organized three-dimensional (3D) nanomaterial architectures are promising candidates for applications in optoelectronics, catalysis, or theranostics owing to their anisotropy and advanced structural features that allow tailoring their physical and chemical properties. The synthesis of such complex but well-organized nanomaterials is difficult because the interplay of interfacial strain and facet-specific reactivity must be considered. Especially the magnetic anisotropy with controlled size and morphology plays a decisive role for applications like magnetic resonance imaging (MRI) and advanced data storage. We present a solution phase seed mediated synthesis of colloidal, well dispersible iron oxide superparticles with flower- and hedgehog-like morphology starting from dispersible spherical maghemite (SPH) and nanoplate hematite (HEX) templates. In the superparticles the templates are epitaxially decorated with nanodomains and nanorods as shown by (high-resolution) transmission electron microscopy (TEM), orientation mapping, and electron diffraction (ED). While the templates determine the morphology of the superparticles, the solution chemistry determines the phase identity. Oxidation of Fe­(CO)5 during superparticle formation reaction leads to maghemite nanodomains and nanorods decorating the templates, unveiled by a combination of X-ray diffraction (XRD) and Mössbauer spectroscopy (MS). After hydrophilic surface functionalization the superparticles are well dispersible. The cytotoxicity of templates and superparticles is low. The magnetic resonance imaging R2-relaxivity of the flower-like superparticles could be increased by a factor 2.5 compared to its spherical nanoparticle template due to direct interfacial connection resulting from the unique nanoarchitecture.

Progress in magnetic Fe3O4nanomaterials in magnetic resonance imaging

“…Certainly, there are other ways, for example, Kluenker et al [26] presented a solution phase seed mediated synthesis of iron oxide superparticles colloidal with flowerand hedgehog-like morphologies starting at dispersible spherical maghemite and nanoplate hematite (HEX) templates to overcome the drawbacks of particle assemblies for functional nanodevices such as low mechanical stability, lack of interfacial electronic communication, and poor processability [27]. Changes in solvent, type of iron salts, and temperatures have been used to synthesize different types of nanomaterials (Figure 2; the NPs are mostly spherical and faceted, and an average particle size is 18-20 nm).…”

“…The specific absorption rate values of MFPLL were 14-15 W g −1 at a frequency of 190 kHz and field strength of c. 8 kA m −1 , which evinces the potential for the application of magnetic hyperthermia. Yin et al [41] [26].…”

Sustainable preparation of sunlight active α-Fe2O3nanoparticles using iron containing ionic liquids for photocatalytic applications

“…Iron oxide nanoparticles (NPs) have attracted great attention from the scientific community due to their potential applications in bio-sensors, 1 bio-electronics, 2 drug delivery, 3 memory devices, 4 gas sensors, 5 magnetic resonance imaging, 3 lithium-ion batteries 6 etc. There are different crystalline forms of iron oxides (FeO, Fe 3 O 4 and Fe 2 O 3 ), and of these Fe 2 O 3 exists in different polymorphs such as, α-Fe 2 O 3 (hematite), β-Fe 2 O 3, ε-Fe 2 O 3 and γ-Fe 2 O 3 (maghemite).…”

Shaping the Assembly of Superparamagnetic Nanoparticles

“…To build micro/macro-size superparamagnetic materials for further applications, superparamagnetic NPs have to be assembled into more complex hierarchical structures. , However, following aggregation and clustering, the magnetization and the coercitivity of the material could change, − and new magnetic response could be observed. , Therefore, the controlled assembly of superparamagnetic NPs is required. Such structures have been prepared by the direct formation of 1D arrays , or by the formation of controlled hybrid clustered beads. ,, Those clustered-beads can themselves undergo further assembly leading to the formation of more complex structures, that is, necklace-like chains. ,, …”

“…12,13 To build micro/macro-size superparamagnetic materials for further applications, superparamagnetic NPs have to be assembled into more complex hierarchical structures. 12,14 However, following aggregation and clustering, the magnetization and the coercitivity of the material could change, 15−20 and new magnetic response could be observed. 21,22 Therefore, the controlled assembly of superparamagnetic NPs is required.…”