Influence of Magnetite Nanoparticles Shape and Spontaneous Surface Oxidation on the Electron Transport Mechanism

P, Alshehri M, Shah NA. Synthesis, Characterization and Investigation of Optical and Electrical Properties of Polyaniline/Nickel Ferrite Composites

Nickel ferrite nanoparticles are prepared by using a low-temperature self-propagating solution combustion method using urea as fuel. The prepared nickel ferrite nanoparticles were doped with polyaniline in the three different weight ratios of 10%, 30% and 50% by using an in situ polymerization method and by adding ammonium persulfate as an oxidizing agent. The obtained samples were characterized by using XRD, FTIR, SEM and a UV-visible spectrophotometer. XRD examined crystalline peaks of ferrites and amorphous peak of polyaniline and confirmed the formation of the composites. FTIR examined the chemical nature of samples and showed peaks due to polyaniline and the characteristic peaks that were less than 1000 cm-1 wavenumber were due to metal-oxygen bond vibrations of ferrites. AC conductivity increased with frequency in all samples and the highest AC conductivity was seen in polyaniline/nickel ferrite 50%. DC conductivity increased in all samples with the temperature showing the semiconducting nature of the samples. Activation energy was evaluated by using Arrhenius plots and there was a decrease in activation energy with the addition of ferrite content. The UV-visible absorption peaks of polyaniline showed shifting in the composites. The optical direct and indirect band gaps were evaluated by plotting Tauc plots and the values of the optical band gap decreased with addition of ferrite in polyaniline and the Urbach energy increased in the samples with 10%, 30% and 50% polyaniline/nickel ferrite composites. The optical properties of these composites with a low band gap can find applications in devices such as solar cells.

Capacitive Electrode-Based Electric Field Treatments on Redox-Toxic Iron Deposits in Transgenic AD Mouse Models: The Electroceutical Targeting of Alzheimer's Disease Feasibility Study

Iron accumulation in the brain accelerates Alzheimer's disease progression. To cure iron toxicity, we assessed the therapeutic effects of noncontact transcranial electric field stimulation to the brain on toxic iron deposits in either the Aβ fibril structure or the Aβ plaque in a mouse model of Alzheimer's disease (AD) as a pilot study. A capacitive electrode-based alternating electric field (AEF) was applied to a suspension of magnetite (Fe₃O₄) to measure field-sensitized reactive oxygen species (ROS) generation. The increase in ROS generation compared to the untreated control was both exposure-time and AEF-frequency dependent. The frequency-specific exposure of AEF to 0.7-1.4 V/cm on a magnetite-bound Aβ-fibril or a transgenic Alzheimer's disease (AD) mouse model revealed the degradation of the Aβ fibril or the removal of the Aβ-plaque burden and ferrous magnetite compared to the untreated control. The results of the behavioral tests show an improvement in impaired cognitive function following AEF treatment on the AD mouse model. Tissue clearing and 3D-imaging analysis revealed no induced damage to the neuronal structures of normal brain tissue following AEF treatment. In conclusion, our results suggest that the effective degradation of magnetite-bound amyloid fibrils or plaques in the AD brain by the electro-Fenton effect from electric field-sensitized magnetite offers a potential electroceutical treatment option for AD.

An Overview of the Production of Magnetic Core-Shell Nanoparticles and Their Biomedical Applications

Several developments have recently emerged for core-shell magnetic nanomaterials, indicating that they are suitable materials for biomedical applications. Their usage in hyperthermia and drug delivery applications has escalated since the use of shell materials and has several beneficial effects for the treatment in question. The shell can protect the magnetic core from oxidation and provide biocompatibility for many materials. Yet, the synthesis of the core-shell materials is a multifaceted challenge as it involves several steps and parallel processes. Although reviews on magnetic core-shell nanoparticles exist, there is a lack of literature that compares the size and shape of magnetic core-shell nanomaterials synthesized via various methods. Therefore, this review outlines the primary synthetic routes for magnetic core-shell nanoparticles, along with the recent advances in magnetic core-shell nanomaterials. As core-shell nanoparticles have been proposed among others as therapeutic nanocarriers, their potential applications in hyperthermia drug delivery are discussed.