bims-mricoa Biomed News
on MRI contrast agents
Issue of 2021‒10‒17
five papers selected by
Merve Yavuz
Bilkent University

  1. Materials (Basel). 2021 Sep 30. pii: 5691. [Epub ahead of print]14(19):
      In this report, the heating efficiencies of γ-Fe2O3 and hybrid γ-Fe2O3-TiO2 nanoparticles NPs under an alternating magnetic field (AMF) have been investigated to evaluate their feasible use in magnetic hyperthermia. The NPs were synthesized by a modified sol-gel method and characterized by different techniques. X-ray diffraction (XRD), Mössbauer spectroscopy and electron microscopy analyses confirmed the maghemite (γ-Fe2O3) phase, crystallinity, good uniformity and 10 nm core sizes of the as-synthesized composites. SQUID hysteresis loops showed a non-negligible coercive field and remanence suggesting the ferromagnetic behavior of the particles. Heating efficiency measurements showed that both samples display high heating potentials and reached magnetic hyperthermia (42 °C) in relatively short times with shorter time (~3 min) observed for γ-Fe2O3 compared to γ-Fe2O3-TiO2. The specific absorption rate (SAR) values calculated for γ-Fe2O3 (up to 90 W/g) are higher than that for γ-Fe2O3-TiO2 (~40 W/g), confirming better heating efficiency for γ-Fe2O3 NPs. The intrinsic loss power (ILP) values of 1.57 nHm2/kg and 0.64 nHm2/kg obtained for both nanocomposites are in the range reported for commercial ferrofluids (0.2-3.1 nHm2/kg). Finally, the heating mechanism responsible for NP heat dissipation is explained concluding that both Neel and Brownian relaxations are contributing to heat production. Overall, the obtained high heating efficiencies suggest that the fabricated nanocomposites hold a great potential to be utilized in a wide spectrum of applications, particularly in magnetic photothermal hyperthermia treatments.
    Keywords:  Sol-Gel synthesis; TiO2; alternating magnetic field; heating efficiency; iron oxide nanoparticles; maghemite; magnetic hyperthermia
  2. Materials (Basel). 2021 Oct 08. pii: 5906. [Epub ahead of print]14(19):
      Magnetite nanoparticles (MNPs) represent one of the most intensively studied types of iron oxide nanoparticles in various fields, including biomedicine, pharmaceutics, bioengineering, and industry. Since their properties in terms of size, shape, and surface charge significantly affects their efficiency towards the envisaged application, it is fundamentally important to develop a new synthesis route that allows for the control and modulation of the nanoparticle features. In this context, the aim of the present study was to develop a new method for the synthesis of MNPs. Specifically, a microfluidic lab-on-chip (LoC) device was used to obtain MNPs with controlled properties. The study investigated the influence of iron precursor solution concentration and flowed onto the final properties of the nanomaterials. The synthesized MNPs were characterized in terms of size, morphology, structure, composition, and stability. Results proved the formation of magnetite as a single mineral phase. Moreover, the uniform spherical shape and narrow size distribution were demonstrated. Optimal characteristics regarding MNPs crystallinity, uniformity, and thermal stability were obtained at higher concentrations and lower flows. In this manner, the potential of the LoC device is a promising tool for the synthesis of nanomaterials by ensuring the necessary uniformity for all final applications.
    Keywords:  iron oxide nanoparticles; lab-on-chip; magnetite nanoparticles; microfluidics
  3. Proc Natl Acad Sci U S A. 2021 Oct 19. pii: e2102340118. [Epub ahead of print]118(42):
      Magnetic nanoparticles are robust contrast agents for MRI and often produce particularly strong signal changes per particle. Leveraging these effects to probe cellular- and molecular-level phenomena in tissue can, however, be hindered by the large sizes of typical nanoparticle contrast agents. To address this limitation, we introduce single-nanometer iron oxide (SNIO) particles that exhibit superparamagnetic properties in conjunction with hydrodynamic diameters comparable to small, highly diffusible imaging agents. These particles efficiently brighten the signal in T 1-weighted MRI, producing per-molecule longitudinal relaxation enhancements over 10 times greater than conventional gadolinium-based contrast agents. We show that SNIOs permeate biological tissue effectively following injection into brain parenchyma or cerebrospinal fluid. We also demonstrate that SNIOs readily enter the brain following ultrasound-induced blood-brain barrier disruption, emulating the performance of a gadolinium agent and providing a basis for future biomedical applications. These results thus demonstrate a platform for MRI probe development that combines advantages of small-molecule imaging agents with the potency of nanoscale materials.
    Keywords:  brain; iron oxide nanoparticle; magnetic resonance imaging; molecular imaging
  4. Int J Biochem Cell Biol. 2021 Oct 07. pii: S1357-2725(21)00175-8. [Epub ahead of print] 106094
      Iron is an essential element for virtually all living things. Body iron levels are tightly controlled as both increased iron levels and iron deficiency are associated with many clinical conditions. Increased iron levels are associated with a worse prognosis in some cancers, so understanding the role of iron in cancer development has thus been an active area of research. Regulated forms of cell death are important in development and disease pathogenesis. In this Medicine in Focus review article, we discuss the role of iron in cancer, and ferroptosis, a new form of iron-regulated cell death triggered by increased iron and peroxidation of lipids. We also review the pathogenesis of cancer, potential therapeutics for targeting the increased requirement of iron, as well as how ferroptosis activation may have a role in treatment of cancers.
    Keywords:  Cancer, iron metabolism, ferroptosis; GPX; hepcidin
  5. Int J Mol Sci. 2021 Oct 04. pii: 10745. [Epub ahead of print]22(19):
      The overexpression of human epidermal growth factor 2 (HER2) in breast cancer (BC) has been associated with a more aggressive tumor subtype, poorer prognosis and shorter overall survival. In this context, the development of HER2-targeted radiotracers is crucial to provide a non-invasive assessment of HER2 expression to select patients for HER2-targeted therapies, monitor response and identify those who become resistant. Antibodies represent ideal candidates for this purpose, as they provide high contrast images for diagnosis and low toxicity in the therapeutic setting. Of those, nanobodies (Nb) are of particular interest considering their favorable kinetics, crossing of relevant biological membranes and intratumoral distribution. The purpose of this review is to highlight the unique characteristics and advantages of Nb-based radiotracers in BC imaging and therapy. Additionally, radiolabeling methods for Nb including direct labeling, indirect labeling via prosthetic group and indirect labeling via complexation will be discussed, reporting advantages and drawbacks. Furthermore, the preclinical to clinical translation of radiolabeled Nbs as promising theranostic agents will be reported.
    Keywords:  HER2 breast cancer; nanobodies; nuclear imaging; radiolabeling strategies; targeted radionuclide therapy