Abstract
Research on iron oxide-based magnetic nanoparticles and their clinical use has been, so far, mainly focused on the spherical shape. However, efforts have been made to develop synthetic routes that produce different anisotropic shapes not only in magnetite nanoparticles, but also in other ferrites, as their magnetic behavior and biological activity can be improved by controlling the shape. Ferrite nanoparticles show several properties that arise from finite-size and surface effects, like high magnetization and superparamagnetism, which make them interesting for use in nanomedicine. Herein, we show recent developments on the synthesis of anisotropic ferrite nanoparticles and the importance of shape-dependent properties for biomedical applications, such as magnetic drug delivery, magnetic hyperthermia and magnetic resonance imaging. A brief discussion on toxicity of iron oxide nanoparticles is also included.
Highlights
Many efforts are being made to overcome the flaws of cancer treatment and diagnosis
T2-weighted MR imaging of a hepatic carcinoma than the spherical ones, indicating that iron oxide octapods are efficient as T2 contrast agents. These results demonstrate that anisotropic shapes promote the increase of the effective radii of nanoparticles enhancing their performance in T2-weighted magnetic resonance imaging (MRI)
Many different strategies have been developed for the reproducible synthesis of high-quality monodisperse anisotropic iron oxide-based magnetic nanoparticles, either through physical, chemical or biological methods
Summary
Many efforts are being made to overcome the flaws of cancer treatment and diagnosis. Nanomedicine is the field of nanotechnology responsible for the development of biomedical tools capable of a higher performance than conventional medicine [1,2]. Ferrite nanoparticles are magnetic nanoparticles that show several properties that result from finite-size and surface effects such as high magnetization, superparamagnetism and extra anisotropy contributions. The fact that these nanoparticles do not retain any magnetization upon removal of an applied magnetic field, along with the low toxicity, biocompatibility and strong magnetic properties, endow iron-based nanoparticles as suitable materials for use in bioimaging, cancer theranostics and drug delivery [3]. Spinel ferrite nanoparticles have ferrimagnetic behavior, and this means that the material is composed of magnetic domains, each one composed of antiparallel magnetic moments with different magnitudes, resulting in a net spontaneous magnetic moment. When a magnetic field is applied, all domains have their magnetic moments aligned with the magnetic field, resulting in a large net magnetic moment [5,6,7,8]
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