Synthesis, Principles, and Properties of Magnetite Nanoparticles for In Vivo Imaging Applications—A Review

Abstract

The current nanotechnology era is marked by the emergence of various magnetic inorganic nanometer-sized colloidal particles. These have been extensively applied and hold an immense potential in biomedical applications including, for example, cancer therapy, drug nanocarriers (NCs), or in targeted delivery systems and diagnosis involving two guided-nanoparticles (NPs) as nanoprobes and contrast agents. Considerable efforts have been devoted to designing iron oxide NPs (IONPs) due to their superparamagnetic (SPM) behavior (SPM IONPs or SPIONs) and their large surface-to-volume area allowing more biocompatibility, stealth, and easy bonding to natural biomolecules thanks to grafted ligands, selective-site moieties, and/or organic and inorganic corona shells. Such nanomagnets with adjustable architecture have been the topic of significant progresses since modular designs enable SPIONs to carry out several functions simultaneously such as local drug delivery with real-time monitoring and imaging of the targeted area. Syntheses of SPIONs and adjustments of their physical and chemical properties have been achieved and paved novel routes for a safe use of those tailored magnetic ferrous nanomaterials. Herein we will emphasis a basic notion about NPs magnetism in order to have a better understanding of SPION assets for biomedical applications, then we mainly focus on magnetite iron oxide owing to its outstanding magnetic properties. The general methods of preparation and typical characteristics of magnetite are reviewed, as well as the major biomedical applications of magnetite.

Polymer-Coated Magnetite Nanoparticles for Protein Immobilization

“…However, the synthesis procedure becomes more complex, time-consuming, and more difficult to scale than the co-precipitation reaction; this method allows obtaining magnetite nanoparticles with very narrow size distribution and well-defined magnetic property [ 16 ]. Additionally, the appropriate proportions of the reagents and temperature control determine the synthesis of MNPs of defined shapes, sizes, and crystallinity.…”

“…The biomedical applications of magnetite nanoparticles are primarily cancer diagnostics and therapies (Magnetic Resonance Imaging, Hyperthermia, Magnetic Field-Assisted Radiotherapy, Photodynamic Therapy), biocatalysis, pharmaceutical analysis, tissue engineering, biosensor, and the immobilization of biomolecules such as proteins [ 3 , 12 , 13 , 14 , 15 ]. However, pure, uncoated magnetite nanoparticles have some limitations in use by reason of the ability to spontaneously form aggregates (a result of the system’s desire to reduce surface energy, both under the influence of the magnetic field and the biological environment) [ 16 ]. Moreover, non-functionalized Fe 3 O 4 nanoparticles are characterized by high chemical activity and susceptibility to oxidation, which often leads to a decrease or complete loss of magnetic properties.…”

“…As already mentioned, the surface of the magnetite core can be coated with various compounds, of which polymers seem to be the most attractive [ 12 ]. Deposition of the polymer on the surface of magnetite nanoparticles provides its chemical and thermal stability [ 16 , 28 , 29 ]. In addition, in the case of nanoparticles coated with polymers, a smaller tendency to their aggregation is observed, which significantly increases their usability [ 30 , 31 ].…”

Magnetite Nanoparticles and Essential Oils Systems for Advanced Antibacterial Therapies

“…Moreover, when applied in biomedicine, the size of MNPs should be <200 nm to avoid rapid spleen and liver filtration and to prolong blood circulation time, but >10 nm to avoid rapid kidney filtration [ 81 ]. Additionally, their size should be designed based on the type of biological entities they are intended for to promote cellular uptake, namely viruses (20–450 nm), proteins (5–50 nm), and cells (10–100 µm) [ 82 ]. MNPs have been synthesized in a variety of shapes, including nanospheres, nanocubes, nanowires, nanotubes, nanoplates, nanohexagons, nanooctahedrons, nanorods, nanorings, nanocapsules, and nanoflowers [ 81 ].…”

Apoferritin Amyloid-Fibril Directed the In Situ Assembly and/or Synthesis of Optical and Magnetic Nanoparticles

“…Great efforts are currently underway to develop new probes for noninvasive imaging techniques such as high-resolution magnetic resonance imaging (MRI) or optical imaging [ 1 , 2 , 3 , 4 ]. While there have been great advances, biomedical imaging still suffers from problems associated with resolution, sensitivity, speed, and penetration depth [ 5 , 6 ].…”