Spatial Organization of Superparamagnetic Iron Oxide Nanoparticles in/on Nano/Microsized Carriers Modulates the Magnetic Resonance Signal

Advances in nanotechnology-based targeted-contrast agents for computed tomography and magnetic resonance

X-ray computed tomography (CT) and magnetic resonance (MR) imaging are essential tools in modern medical diagnosis and treatment. However, traditional contrast agents are inadequate in the diagnosis of various health conditions. Consequently, the development of targeted nano-contrast agents has become a crucial area of focus in the development of medical image-enhancing contrast agents. To fully understand the current development of nano-contrast agents, this review provides an overview of the preparation methods and research advancements in CT nano-contrast agents, MR nano-contrast agents, and CT/MR multimodal nano-contrast agents described in previous publications. Due to the physicochemical properties of nanomaterials, such as self-assembly and surface modifiability, these specific nano-contrast agents can greatly improve the targeting of lesions through various preparation methods and clearly highlight the distinction between lesions and normal tissues in both CT and MR. As a result, they have the potential to be used in the early stages of disease to improve diagnostic capacity and level in medical imaging.

Iron Oxide Nanoparticles: A Review on the Province of Its Compounds, Properties and Biological Applications

Materials science and technology, with the advent of nanotechnology, has brought about innumerable nanomaterials and multi-functional materials, with intriguing yet profound properties, into the scientific realm. Even a minor functionalization of a nanomaterial brings about vast changes in its properties that could be potentially utilized in various applications, particularly for biological applications, as one of the primary needs at present is for point-of-care devices that can provide swifter, accurate, reliable, and reproducible results for the detection of various physiological conditions, or as elements that could increase the resolution of current bio-imaging procedures. In this regard, iron oxide nanoparticles, a major class of metal oxide nanoparticles, have been sweepingly synthesized, characterized, and studied for their essential properties; there are 14 polymorphs that have been reported so far in the literature. With such a background, this review's primary focus is the discussion of the different synthesis methods along with their structural, optical, magnetic, rheological and phase transformation properties. Subsequently, the review has been extrapolated to summarize the effective use of these nanoparticles as contrast agents in bio-imaging, therapeutic agents making use of its immune-toxicity and subsequent usage in hyperthermia for the treatment of cancer, electron transfer agents in copious electrochemical based enzymatic or non-enzymatic biosensors and bactericidal coatings over biomaterials to reduce the biofilm formation significantly.

Structure-Correlated Magnetic Resonance Transverse Relaxivity Enhancement in Superparamagnetic Ensembles with Complex Anisotropy Landscape

The aim of the work is to explore structure-relaxivity relationship by observing transverse relaxivity enhancement in magnetic resonance imaging (MRI) of differently organized superparamagnetic complex ensembles of zinc ferrite isotropic/anisotropic nanosystems. We observe that superparamagnetic systems show a correlation of MRI-transverse relaxivity, r₂/r₁, with spatial arrangement of nanoparticles, as well as magnetic easy axes and thermal-energy-dependent anisotropy energy landscape. The presence of highly random/partially aligned easy axes with enhanced anisotropy constant leads to modulation in transverse relaxation. As a result, we achieve highest contrast efficiency in compact ensemble of isotropic nanoparticles and hollow core ensemble. Indeed, core-shell ensemble with combined effect of aligned and randomly oriented easy magnetic axes shows a reduction in MRI contrast efficiency. However, we address a hypothesis for transverse contrast efficiency where we depict the correlation among MRI-transverse contrast efficiency with structural complexity of ensembles, differently arranged primary nanoparticles/magnetic easy axes, anisotropy constant, and collective magnetic behavior. In consequence, we simplify the limitation of quantum mechanical outer-sphere diffusion model of magnetic resonance relaxivity by neglecting the contribution of magnetization and introducing an anisotropy constant contribution with complex structure landscape of easy axes.

Supramolecular-micelle-directed preparation of uniform magnetic nanofibers with length tunability, colloidal stability and capacity for surface functionalization

We report a versatile and efficient platform to prepare uniform magnetic nanofibers with length tunability, colloidal and morphological stability, capacity for surface functionalization and enhanced T₂ contrast.

Fe3O4 Nanoparticles Functionalized with Polymer Ligand for T1-Weighted MRI In Vitro and In Vivo

Magnetic resonance imaging (MRI) has gained wide interest in early accurate diagnoses due to the high resolution and low toxicity of magnetic nanoparticles. In order to develop potential alternatives of toxic Gd- or Mn-based chelating agents, we report the synthesis of water soluble ultra-small Fe3O4 nanoparticles by a modified co-precipitation method as T1-weighted positive contrast agents. The magnetic iron oxide nanoparticles (MIONs) were functionalized by polymer ligand dodecanthiol-polymethacrylic acid (DDT-PMAA) to enhance their colloidal stability. These MIONs have high longitudinal relaxivity (r1 = 8.18 mM-1·S-1) and exhibited good results in the in vitro and in vivo MR imaging. No toxicity was observed in cytotoxicity assay and histology toxicity analysis. The MIONs@DDT-PMAA(magnetic iron oxide nanoparticles @ dodecanthiol-polymethacrylic acid) present great potential as positive contrast agents for tumor diagnosis.