SPIN

Assemblies of magnetic nanoparticles show a great potential for application in biomedicine, particularly, magnetic hyperthermia. However, to achieve desired therapeutic effect in magnetic hyperthermia, the assembly of nanoparticles should have a sufficiently high specific absorption rate (SAR) in alternating magnetic field of moderate amplitude and frequency. Using the Landau–Lifshitz stochastic equation, it is shown that dilute assemblies of iron oxide nanoparticles of optimal diameters are capable of providing SAR of the order of 400–600W/g in alternating magnetic field with the amplitude $H_0=100$Oe in the frequency range f = 300–500kHz. Unfortunately, in dense clusters of magnetic nanoparticles, which are often formed in a biological medium, there is a sharp decrease in SAR due to the influence of strong magneto-dipole interaction of closest nanoparticles. To overcome this difficulty, it is suggested covering the nanoparticles with nonmagnetic shells of sufficient thickness or using non-single-domain nanoparticles being in magnetization curling states.

In this review, we introduce various magnetic biosensors that have been developed. We first explain the advantages of magnetic biosensing and their general operating principles as well as the biolabeling technique for magnetic nanoparticles. Next, we focus on magnetoresistive biosensing technologies because magnetoresistive biosensors will be an essential development direction due to the demand for miniaturization and portable lab-on-a-chip devices. The magnetoresistive effects employed in biosensing include anisotropic magnetoresistance, giant magnetoresistance and tunneling magnetoresistance. In addition to magnetoresistive sensors, the advantages and disadvantages of some nonmagnetoresistive magnetic biosensors are discussed and compared. Finally, we introduce research on integrating magnetic biosensors into the microfluidic laboratory-on-a-chip systems and comment on future development trends.

Iron oxide nanoparticles (NPs) have been a very appealing choice in magnetic-mediated hyperthermia for cancer therapy. The responses of NPs to hyperthermia as a cancer treatment method are complex and variable. Herein, the heating properties of the casein-coated magnetic NPs (MNPs) under an alternating magnetic field were investigated. The casein-coated MNPs were synthesized via one-pot chemical method. The casein-coated MNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), and vibrating sample magnetometer (VSM) analysis. TEM images of casein-coated MNPs show that their shapes are spherical and their core sizes are between 20nm and 25nm. The FTIR and EDAX results confirmed the presence of casein on the surface of MNPs. The VSM shows the superparamagnetic nature of iron oxide and casein-coated iron oxide NPs with the magnetic saturation of 60emu/g and 44.86emu/g, respectively, at room temperature. Furthermore, hyperthermia tests for casein-coated MNPs with various concentrations and frequencies are performed. Hyperthermia results show that lower concentrations of casein-coated MNPs dispatch higher heating into their surrounding medium, whereas maximum specific absorption rate occurs at the concentration of 1mg/mL for the frequency of 150kHz. Findings of this study suggest that casein-coated MNPs have great potential as an anticancer agent in hyperthermia cancer therapy.

Hereby, a sonochemical method for synthesis of pure magnetic Fe₃O₄ nanoparticles (Fe₃O₄-NPs) in large scale is being introduced. Synthesis proceeds via simple approach, at room temperature, under sonication, using cheap reagents, green antioxidant-reductant reagent and without using inert gas purge as protective atmosphere condition. During this procedure, hydrogen gas releases continuously as valuable byproduct at the anaerobic step of reaction. Characterizations’ results indicate that the final product is pure spherical Fe₃O₄-NPs, with narrow size distribution and about less than 32nm in mean diameter while more than 99% of particles size were less than 40nm. According to Vibrational Sampling Magnetometer (VSM) result, NPs pose high saturation magnetization of about 77 (emu/g) and magnetization curve shows superparamagnetic behavior with no hysteresis loop. Also by various weight ratios, these NPs performed stable dispersion in aqueous media for long times. Iron oxide NPs show nontoxicity for lower dosage of 10$\mu$g/mL in 24h on fibroblast cell. Hyperthermia results show maximum heating efficiency in 100KHz for 1mg/mL of NPs.

Superparamagnetic iron oxide (SPIO) has been used as a contrast agent for magnetic resonance imaging (MRI) since the late 20th century. With the development of SPIO, cellular MRI has been recognized as a suitable and highly sensitive noninvasive modality with great potential to benefit translational research. In addition to its traditional diagnostic property, latest advances have conferred SPIO with multifunctionality. Several SPIO-based theranostic probes with targeting, therapeutic and diagnosis components have been successfully developed. The objective of this brief review is to summarize the characteristics, synthesizing methods, labeling approaches and current applications of SPIO-based cellular MRI in oncology. Herein, we first depict the history, classification and advantages of and the differences between T1- and T2/T2*-based SPIO contrast agents for cancer treatment. Second, we outline current coating materials that render SPIO less toxic and more biocompatible to mammalian cells. Finally, the cell labeling techniques and applications of SPIO-based MRI for tracking mesenchymal stem cell tumor–homing in preclinical models are introduced.

In this work, we used the modified Hummers method to synthesize graphene oxide, and the redox reaction of FeCl${}_3\cdot 6$H₂O with the carboxyl group on the surface of acidified graphene was carried out to prepare magnetic nanoparticles modified on the surface of graphene (magnetic graphene nanocomposite). X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM) and Brunauer–Emmett–Teller measurement (BET) analyses were used to characterize the nanocomposite properties. SEM and TEM images of the nanocomposite show that the magnetic nanoparticles are distributed on both sides of the graphene, and the magnetic nanoparticles diameter is between 100 and 150nm. The XRD pattern indicates that the magnetic nanoparticles are Fe₃O₄ nanoparticles. Based on the VSM, the nanocomposite exhibits a saturation magnetization value of 14.94$\mathrm{\text{emu}}\cdot {\mathrm{\text{g}}}^{-1}$. By BET measurement, the specific surface area of the nanocomposite is 26.54m${}^2\cdot {\mathrm{\text{g}}}^{-1}$, and the surface of the nanocomposite is highly porous. In the experiment of dyes adsorption, the adsorption efficiency in the solution was close to 100%. It can be applied in biomedical and environmental fields such as water purification owing to its high surface, magnetic attraction properties and good adsorption efficiency.

The three-dimensional (3D) nano scaffold of the cellulose acetate (CA) containing graphene/cobalt nanocomposite (0.1wt.%) was fabricated via electrospinning technique, and its impact on bone regeneration was investigated. Through this aim, bone marrow mesenchymal stem cells are cultured on the CA, and graphene/cobalt (rGO/Co)/CA nanocomposite scaffold surfaces and the samples are treated under low frequency alternative magnetic field (75Hz). The scaffolds are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal studies (TG/DSC). The proliferation behavior of stem cells on CA, and rGO/Co/CA nano scaffolds are studied by MTT assay, show their biocompability after 14 days of cell seeding. The 6-diamidino-2-phenylindole (DAPI) staining is used to confirm the morality of stem cell for duration of seven days. The nanocomposite scaffold is enhanced for extremely higher proliferation compared to the bare CA scaffold. The acceleration on osteogenic differentiation on the bone mesenchymal stem cell is enhanced within 48h when rGO/Co/CA scaffold is placed under alternative current magnetic field (ACMF). Furthermore, the acceleration of the stem cells differentiation for the rGO/Co/CA scaffold under ACMF corresponds to the induced scaffold surface roughness caused by graphene sheets, the metallic behavior of graphene and the responding of the nanocomposite magnetic parts (i.e., cobalt nanoparticles) while applying 75Hz frequency. Using reverse transcription polymerase chain reaction (RT-PCR) analysis, the superior effect of ACMF on scaffold contain magnetic graphene nanocomposite is confirmed to produce bone related genes within 14 days.

Various routes to low energy consumption magnetic electronics and magnetic memory are reviewed including field effect spintronics, magnetoelectric magnonics and straintronics. The new idea of biologically inspired straintronic image processing scheme as well as the new experimental results on electric field induced magnetic anisotropy modulation in iron garnet films are presented.

The magnetic community continues to discuss the possibility of observing the magnetic superfluidity, despite the fact that it has been discovered a long time ago. It was observed in antiferromagnetic states of superfluid ³He in 1984. In this paper, we reiterate the main principles of spin superfluidity and related Bose–Einstin magnon condensation. We discuss applications of this phenomenon in supermagnonic devises.