Insights into the Dielectric Loss Mechanism of Bianisotropic FeSi/SiC Composite Materials.

High magnitudes of permittivity with the permeability of the materials help to absorb electromagnetic waves more efficiently. Snoek's limit directly puts a constraint on the enhancement of the permeability of the material. However, the incorporation of the lossy material may help to enhance the permittivity abruptly. In this study, we prepared a FeSi/SiC composite material with the mechanical ball milling method and investigated its enhancement of the dielectric behavior. The bianisotropic nature was observed along with the phase purity in the morphological studies. The Cole-Cole relaxation mechanisms were observed to validate a complex relaxation mechanism with 104 times higher dielectric loss in the composite material. The detection of the Warburg capacitance using the impedance technique sheds new light on the ion diffusion mechanism in the metallic composite materials.

Emerging chemical strategies for imprinting magnetism in graphene and related 2D materials for spintronic and biomedical applications.

Graphene, a single two-dimensional sheet of carbon atoms with an arrangement mimicking the honeycomb hexagonal architecture, has captured immense interest of the scientific community since its isolation in 2004. Besides its extraordinarily high electrical conductivity and surface area, graphene shows a long spin lifetime and limited hyperfine interactions, which favors its potential exploitation in spintronic and biomedical applications, provided it can be made magnetic. However, pristine graphene is diamagnetic in nature due to solely sp2 hybridization. Thus, various attempts have been proposed to imprint magnetic features into graphene. The present review focuses on a systematic classification and physicochemical description of approaches leading to equip graphene with magnetic properties. These include introduction of point and line defects into graphene lattices, spatial confinement and edge engineering, doping of graphene lattice with foreign atoms, and sp3 functionalization. Each magnetism-imprinting strategy is discussed in detail including identification of roles of various internal and external parameters in the induced magnetic regimes, with assessment of their robustness. Moreover, emergence of magnetism in graphene analogues and related 2D materials such as transition metal dichalcogenides, metal halides, metal dinitrides, MXenes, hexagonal boron nitride, and other organic compounds is also reviewed. Since the magnetic features of graphene can be readily masked by the presence of magnetic residues from synthesis itself or sample handling, the issue of magnetic impurities and correct data interpretations is also addressed. Finally, current problems and challenges in magnetism of graphene and related 2D materials and future potential applications are also highlighted.

Polymer Stabilized Fe3O4-Graphene as an Amphiphilic Drug Carrier for Thermo-Chemotherapy of Cancer.

In light of the growing interest in the search for cheap and effective solutions for cancer treatment, we report a simple one pot synthesis of polymer stabilized iron oxide-graphene (PIG) that could be realized on a large scale. The structural (Fe3O4 particle size of ∼11 nm), functional (various oxygen containing moieties), and magnetic (moment of ∼43 emu/g) properties of PIG are explored using various characterization techniques for possible biomedical applications. PIG shows good colloidal stability and is biocompatible even at higher concentrations (2.5 mg/mL) by virtue of cross-linking polymers. The biocompatibility of the composite has been tested using HeLa cell lines by computing the percentage of the reactive oxygen species through the 2,7-dichlorofluorescein (DCF) intensity level. PIG has the ability to load and release both hydrophobic and hydrophilic drugs with a good loading efficiency and capacity. The dug loading efficiency of PIG is measured to be ∼87% and ∼91% for doxorubicin (DOX) and paclitaxel (PTXL), respectively. Under an AC magnetic field, superparamagnetic PIG (2.5 mg/mL) takes less than 16 min to reach the stable hyperthermia temperature, suggesting it as a good anticancer material. A time-dependent cellular uptake of doxorubicin-conjugated PIG has been studied to optimize the parameters for thermo-chemotherapy of cancer. The synergetic effect of both the drug and hyperthermia is observed in the killing of the cancerous cells, verified by computing the cell apoptotic population using a flow cytometer. However, it has been noticed that, even in the absence of chemotherapy, PIG shows good antiproliferative activity with thermotherapy alone.