Localized heat induction using magnetic nanoparticles under an alternating magnetic field is an emerging technology applied in areas including, cancer treatment, thermally activated drug release and remote activation of cell functions. To enhance the induction heating efficiency of magnetic nanoparticles, the intrinsic and extrinsic magnetic parameters influencing the heating efficiency of magnetic nanoparticles should be effectively engineered. This review covers the recent progress in the optimization of magnetic properties of spinel ferrite nanoparticles for efficient heat induction. The key materials factors for efficient magnetic heating including size, shape, composition, inter/intra particle interactions are systematically discussed, from the growth mechanism, process control to chemical and magnetic properties manipulation.

/pdf/inductive-thermal-effect-of-ferrite-magnetic-nanoparticles-1a19k4ng07.pdf

Inductive Thermal Effect of Ferrite Magnetic Nanoparticles

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications.

Monodispersed CoFe2O4 nanoparticles were synthesized by the thermal decomposition of Co and Fe acetylacetonate in octadecene, which contained oleic acid (OA) and oleylamine (OLA). The hydrophobicity of the CoFe2O4 nanoparticles was alleviated such that they were water dispersible by encapsulating them with poly(maleic anhydride-alt-1-octadecene) (PMAO). The heating ability of these magnetic fluids was assessed by calorimetry measurement of specific absorption rate under an alternating magnetic field of 300 Oe within the frequency interval of 290–450 kHz. The highest value of the specific absorption rate was 297.4 W g−1 for a sample concentration of 1 mg mL−1 under an applied field of 300 Oe and frequency of 450 kHz. Linear response theory was used to explain the results. The high specific absorption rate of the nanofluid based on PMAO-encapsulated CoFe2O4@OA/OLA showed that it may meet the requirements for practical applications in tumor-targeted hyperthermia treatment. In vitro cytotoxicity analysis was also performed on Sarcoma 180 cancer cells, and the results showed that these nanoparticles were nontoxic to cells.

Polymer-coated cobalt ferrite nanoparticles: synthesis, characterization, and toxicity for hyperthermia applications

Core–shell CoFe2O4@HAp magnetic nanoparticles were successfully prepared by a simple two-step hydrothermal process, and their physicochemical and magnetic properties were studied. X-ray diffraction and Fourier transform infrared spectroscopy of the as-synthesized samples reveal that the nanoparticles are composed of both phases (HAp@CoFe2O4). The core–shell formation was confirmed by TEM and from the magnetization studies using a vibrating sample magnetometer (VSM), and the ferromagnetic nature of the synthesized core–shell nanoparticles at room temperature was confirmed by saturation magnetization (Ms) and coercivity values of 9.04 emu g−1 and 0.1 T, respectively. It has been observed that heat treatment enhanced the saturation magnetization when compared to the as-prepared samples. The reason for this enhanced magnetic property after heat treatment is discussed based on the magnetic moment and anisotropy calculations. The potential cytocompatibility of the sample was confirmed by fibroblast 3T3 cells.

Fabrication of core–shell CoFe2O4@HAp nanoparticles: a novel magnetic platform for biomedical applications

Heating at the nanoscale is the basis of several biomedical applications, including magnetic hyperthermia therapies and heat-triggered drug delivery. The combination of multiple inorganic materials in hybrid magnetic nanoparticles provides versatile platforms to achieve an efficient heat delivery upon different external stimuli or to get an optical feedback during the process. However, the successful design and application of these nanomaterials usually require intricate synthesis routes and their magnetic response is still not fully understood. In this review we give an overview of the novel systems reported in the last few years, which have been mostly obtained by organic phase-based synthesis and epitaxial growth processes. Since the heating efficiency of hybrid magnetic nanoparticles often relies on the exchange-interaction between their components, we discuss various interface-phenomena that are responsible for their magnetic properties. Finally, followed by a brief comment on future directions in the field, we outline recent advances on multifunctional nanoparticles that can boost the heating power with light and combine heating and temperature sensing in a single nanomaterial.

/pdf/hybrid-magnetic-nanoparticles-as-efficient-nanoheaters-in-1yynksag6s.pdf

Hybrid magnetic nanoparticles as efficient nanoheaters in biomedical applications

We report a systematic study of the effects of core and shell size on the magnetic properties and heating efficiency of exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles. The nanoparticles were synthesized using thermal decomposition of organometallic precursors. Transmission electron microscopy (TEM) confirmed the formation of spherical Fe3O4 and Fe3O4/CoFe2O4 nanoparticles. Magnetic measurements showed high saturation magnetization for the nanoparticles at room temperature. Increasing core diameter (6.4±0.7, 7.8±0.1, 9.6±1.2 nm) and/or shell thickness (∼1, 2, 4 nm) increased the coercive field (HC), while an optimal value of saturation magnetization (MS) was achieved for the Fe3O4 (7.8±0.1nm)/CoFe2O4 (2.1±0.1nm) nanoparticles. Magnetic hyperthermia measurements indicated a large increase in specific absorption rate (SAR) for 8.2±1.1 nm Fe3O4/CoFe2O4 compared to Fe3O4 nanoparticles of same size. The SAR of the Fe3O4/CoFe2O4 nanoparticles increased from 199 to 461 W/g for 800 Oe as the thickness of ...

/pdf/exchange-coupled-fe-3-o-4-cofe-2-o-4-nanoparticles-for-2bubevcady.pdf

Josue Robles

Papers

Exchange-Coupled Fe 3 O 4 /CoFe 2 O 4 Nanoparticles for Advanced Magnetic Hyperthermia