A study of the properties of core/shell/shell Ag/FeCo/Ag nanoparticles

© 2017, Pleiades Publishing, Ltd. The properties of heterophase core/shell/shell Ag/FeCo/Ag nanoparticles synthesized via a plasma method that are promising for biological applications are studied. As is established, the core/shell/shell Ag/FeCo/Ag nanoparticles exhibit a superparamagnetic state at room temperature that allows one to manage the hyperthermia process. The magnetic characteristics of core/shell/shell Ag/FeCo/Ag nanoparticles are interpreted by assuming partial oxidation of the surface layer of a ferromagnetic FeCo shell and formation of the antiferromagnetic Co x Fe 1–x О layer on the FeCo surface. The interaction between the surface antiferromagnetic Co x Fe 1–x О layer and the ferromagnetic FeCо shell causes the emergence of the exchange bias in Ag/FeCo/Ag nanoparticles

編集委員

© 2017, Pleiades Publishing, Ltd. The properties of heterophase core/shell/shell Ag/FeCo/Ag nanoparticles synthesized via a plasma method that are promising for biological applications are studied. As is established, the core/shell/shell Ag/FeCo/Ag nanoparticles exhibit a superparamagnetic state at room temperature that allows one to manage the hyperthermia process. The magnetic characteristics of core/shell/shell Ag/FeCo/Ag nanoparticles are interpreted by assuming partial oxidation of the surface layer of a ferromagnetic FeCo shell and formation of the antiferromagnetic Co x Fe 1–x О layer on the FeCo surface. The interaction between the surface antiferromagnetic Co x Fe 1–x О layer and the ferromagnetic FeCо shell causes the emergence of the exchange bias in Ag/FeCo/Ag nanoparticles

Evaluation of Antiproliferative Properties of CoMnZn-Fe₂O₄ Ferrite Nanoparticles in Colorectal Cancer Cells

The PEG-coated ferrite nanoparticles Co0.2Mn0.6Zn0.2Fe2O4 (X1), Co0.4Mn0.4Zn0.2Fe2O4 (X2), and Co0.6Mn0.2Zn0.2Fe2O4 (X3) were synthesized by the coprecipitation method. The nanoparticles were characterized by XRD, Raman, VSM, XPS, and TEM. The magnetic hyperthermia efficiency (MH) was determined for PEG-coated nanoparticles using an alternating magnetic field (AMF). X2 nanoparticles displayed the highest saturation magnetization and specific absorption rate (SAR) value of 245.2 W/g for 2 mg/mL in a water medium. Based on these properties, X2 nanoparticles were further evaluated for antiproliferative activity against HCT116 cells at an AMF of 495.25 kHz frequency and 350 G strength, using MTT, colony formation, wound healing assays, and flow cytometry analysis for determining the cell viability, clonogenic property, cell migration ability, and cell death of HCT116 cells upon AMF treatment in HCT116 cells, respectively. We observed a significant inhibition of cell viability (2% for untreated control vs. 50% for AMF), colony-forming ability (530 cells/colony for untreated control vs. 220 cells/colony for AMF), abrogation of cell migration (100% wound closure for untreated control vs. 5% wound closure for AMF), and induction of apoptosis-mediated cell death (7.5% for untreated control vs. 24.7% for AMF) of HCT116 cells with respect to untreated control cells after AMF treatment. Collectively, these results demonstrated that the PEG-coated (CoMnZn-Fe2O4) mixed ferrite nanoparticles upon treatment with AMF induced a significant antiproliferative effect on HCT116 cells compared with the untreated cells, indicating the promising antiproliferative potential of the Co0.4Mn0.4Zn0.2Fe2O4 nanoparticles for targeting colorectal cancer cells. Additionally, these results provide appealing evidence that ferrite-based nanoparticles using MH could act as potential anticancer agents and need further evaluation in preclinical models in future studies against colorectal and other cancers.</p

Studying the ferromagnetic–paramagnetic phase transition in thin films of L1<inf>0</inf> FePt<inf>1–x</inf>Rh<inf>x</inf>

© 2015, Allerton Press, Inc. FePtRh films with different Rh concentrations (FePt1–xRhx) are fabricated by magnetron sputtering. The magnetic structure and ferromagnetic–paramagnetic phase transition in thin films of L10 FePt1–xRhx with different Rh concentrations (0 ≤ x ≤ 0.40) are studied. It is demonstrated that thin films of FePt1–xRhx with 0 < x < 0.34 are in the ferromagnetic state with high magnetocrystalline anisotropy energy at room temperature, while similar films with 0.34 < x < 0.4 are paramagnetic

Controlling Magnetization Reversal and Hyperthermia Efficiency in Core-Shell Iron-Iron Oxide Magnetic Nanoparticles by Tuning the Interphase Coupling

Magnetic particle hyperthermia, in which colloidal nanostructures are exposed to an alternating magnetic field, is a promising approach to cancer therapy. Unfortunately, the clinical efficacy of hyperthermia has not yet been optimized. Consequently, routes to improve magnetic particle hyperthermia, such as designing hybrid structures comprised of different phase materials, are actively pursued. Here, we demonstrate enhanced hyperthermia efficiency in relatively large spherical Fe/Fe-oxide core-shell nanoparticles through the manipulation of interactions between the core and shell phases. Experimental results on representative samples with diameters in the range 30-80 nm indicate a direct correlation of hysteresis losses to the observed heating with a maximum efficiency of around 0.9 kW/g. The absolute particle size, the core-shell ratio, and the interposition of a thin wüstite interlayer are shown to have powerful effects on the specific absorption rate. By comparing our measurements to micromagnetic calculations, we have unveiled the occurrence of topologically nontrivial magnetization reversal modes under which interparticle interactions become negligible, aggregates formation is minimized and the energy that is converted into heat is increased. This information has been overlooked until date and is in stark contrast to the existing knowledge on homogeneous particles