CoNiZn and CoNiFe Nanoparticles: Synthesis, Physical Characterization, and In Vitro Cytotoxicity Evaluations

The polyol method has been used to synthesize CoNiFe and CoNiZn alloy nanoparticles (NPs). The magnetic characteristics of the products have been measured by vibration sample magnetometry (VSM) analysis. At the same time, the microstructure and morphology were inspected by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Magnetic measurement of samples by the VSM indicated that samples have soft ferromagnetic behavior. Spherical-shaped grains for samples were confirmed by the SEM. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and lactate dehydrogenase (LDH) assays were used to determine the cytotoxic effects of the synthesized NPs. Cytotoxic evaluations showed that treatment with 25 to 400 µg/mL of CoNiZn and CoNiFe NPs exerted a significant time- and concentration-dependent toxicity in MCF7 and HUVEC cells and markedly enhanced the LDH leakage after 48 h of exposure (p < 0.05 compared with untreated cells). Furthermore, NPs with concentrations higher than 12.5 µg/mL induced evident morphological changes in the studied cell lines. Treatment with 12.5 µg/mL of CoNiZn and CoNiFe NPs was safe and did not affect normal human cell survival. The results of in vitro cytotoxicity assessments show promise in supporting the suitability of the synthesized NPs to build high-performance theranostic nanoplatforms for simultaneous cancer imaging and therapy without affecting normal human cells.

Synthesis and characterization of high-temperature resistant and thermally conductive magnetic PBI/Fe3O4 nanofibers

In the present study, magnetite nanoparticles were added to an electrospinning solution of polyvinylidene fluoride (PVDF)/polybenzimidazole (PBI) polymers to prepare PBI/Fe3O4 nanofibers (NFs). The operating voltage of the electrospinning device was set to 15 kV, the distance between the needle and the plate was 10 cm, and the feed rate was set to 0.3 mL h−1. The microstructures of the as-prepared NFs were investigated by Fourier transform infrared spectrophotometry, atomic force microscopy, thermogravimetric analysis, and vibration sample magnetometry. Magnetite-doped PVDF/PBI NFs exhibited superior magnetism and saturation magnetization in the range of 1.5–5 emu g−1. It was observed that the thermal resistance of the fibers increased with the increasing amount of magnetic particles and nanocomposite fiber (NCF) 1 and NCF2 exhibited excellent thermal resistance up to 415°C and 450°C, respectively. The heat conduction coefficient of the fibers was measured at 4, 6, and 8 W. The thermal conductivity of the NFs increased with the increasing amount of magnetite nanoparticles, and the highest thermal conductivity coefficient for NCF2 (1.83 W mK−1) was measured at 4 W.

Secondary recycled acrylonitrile–butadiene–styrene and graphene composite for 3D/4D applications: Rheological, thermal, magnetometric, and mechanical analyses

This study reports investigation on nano-sized (5–10 nm) graphene (Gr)-reinforced, secondary (2°) recycled acrylonitrile–butadiene–styrene (ABS) as a smart composite material for 3D and 4D applications. Gr was blended (in different weight proportions) with 2°-recycled ABS granules mechanically for selection of composition/proportion after ascertaining rheological property (based upon melt flow index according to ASTM D 1238), thermal stability based upon differential scanning calorimetry, and magnetic property based upon vibration sample magnetometry. The selected compositions/proportions of ABS-Gr composite was further processed with a twin-screw extruder by varying screw temperature and torque. The results of the study suggest that as regards to mechanical properties (peak strength and Shore D hardness) are concerned, the best settings are 20 wt% Gr reinforcement in ABS at a screw temperature 210°C with torque of 0.4 Nm. The corresponding heat capacity and magnetization for the selected composition/proportion was observed as 0.77 J/g and 0.10 × 10−5 emu (+magnetization), 0.080 × 10−5 emu (−magnetization), respectively. The coercivity of the selected compositions ranges from 79.19 Oe to 1260.34 Oe (+coercivity) and 4.64 Oe to 639.50 Oe (−coercivity), whereas the retentivity of the investigated compositions ranges from 2.36 × 10−5 G to 5.44 × 10−4 G (+retentivity) and 4.31 × 10−5 G to 3.48 × 10−5 G (−retentivity). The results have been counter verified based upon optical photo micrographs, porosity analysis, scanning electron microscopy analysis, and energy-dispersive spectroscopy analysis.

Facile method for the selective recover of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

Rare earth elements (REE) are essential for the production of technological devices. However, their high demand and low availability, together with an increase in electronic waste generation, compel the development of efficient, economic and green methods for recovering these elements from electronic waste. In this work, a facile method for selective recovering of REE from Liquid Crystal Display (LCD) screen wastes, employing ultrasound assisted leaching is presented. The screen wastes were milled and sieved to pass through − 325 mesh sieve. The milled powder was summited to ultrasound-assisted leaching in aqueous medium, at room temperature (25 °C) and pH 6 for 60 minutes. Subsequently, a magnetic separation was applied into the leach residue. ICP was employed to quantitatively analyze the composition of the LCD powders and the effectiveness of the extraction process. SEM-EDS allowed qualitatively analyzing the chemical composition of the solid materials. The results shown that the LCD screen wastes are formed, mainly, by amorphous oxides of Si, Fe, In, Sn and REE. The amount of Gd and Pr in the wastes were 93 mg/kg and 24 mg/kg, respectively; It represents enough reason to recover it. X-ray diffraction analysis of the magnetic portion of the leaching residue, confirmed the presence of an amorphous phase together with crystalline metallic iron alloy. The magnetic behavior, obtained by Vibration Sample Magnetometry, helped to understand the nature of the residues. The formation of this metallic alloy is attributed to the effect of high power ultrasonic during the leaching. It was confirmed that the magnetic residues concentrates and recovers 87 wt. % of Gd and 85 wt. % of Pr of the total content of these REE in the magnetic residue. Therefore, ultrasound-assisted leaching is a selective and facile method for recovering Gd and Pr from a screen wastes.

Effective degradation of tetracycline by magnetic palygorskite synthesized with different dosages of NaOH

In the process of preparing magnetic palygorskite from waste pickling liquor of the steel industry, the dosage of NaOH will affect the properties of the magnetic palygorskite. The experimental results showed that magnetic palygorskite can be effectively prepared when NaOH dosage is between 255 and 330 g/L. Vibration sample magnetometry proved that different NaOH dosages can affect the saturation magnetization of magnetic palygorskite. The catalytic performance of five catalysts synthesized with different NaOH dosages hardly changed after five cycles of Fenton-like catalytic degradation of tetracycline (TC). The magnetic palygorskite prepared by this method had good catalytic performance even when the catalyst preparation conditions were magnified ten times, which can provide a reference for large-scale preparation of magnetic palygorskite.

Temperature Dependence of the Magnetic Properties of IrMn/CoFeB/Ru/CoFeB Exchange Biased Synthetic Antiferromagnets

Synthetic antiferromagnets (SAF) are widely used for a plethora of applications among which data storage, computing, and in the emerging field of magnonics. In this framework, controlling the magnetic properties of SAFs via localized thermal treatments represents a promising route for building novel magnonic materials. In this paper, we study via vibration sample magnetometry the temperature dependence of the magnetic properties of sputtered exchange bias SAFs grown via magnetron sputtering varying the ferromagnetic layers and spacer thickness. Interestingly, we observe a strong, reversible modulation of the exchange field, saturation field, and coupling strength upon heating up to 250 °C. These results suggest that exchange bias SAFs represent promising systems for developing novel artificial magnetic nanomaterials via localized thermal treatment.

Synthesis of Poly(N-vinylcaprolactam)-Grafted Magnetite Nanocomposites for Magnetic Hyperthermia

In this study, the synthesis, characterization, and application of poly(N-vinylcaprolactam)-grafted magnetite nanocomposites for magnetic hyperthermia are reported. Superparamagnetic magnetite nanoparticles (MagNPs) with sizes in the range of 10–16 nm were synthesized by the coprecipitation method and then functionalized with vinyltrimethoxysilane (VTMS). MagNPs-VTMS coated with poly(N-vinylcaprolactam) (PNVCL) were prepared by free radical polymerization. The obtained materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibration sample magnetometry (VSM), and Fourier transform infrared spectroscopy (FT-IR). The heating ability was evaluated under a magnetic field using a solid state induction heating equipment at 10.2 kA/m and 362 kHz. The MagNPs-PNVCL nanocomposites showed a behavior close to superparamagnetic materials, which is appropriated for magnetic hyperthermia treatment; in concentrations of 8 mg/mL, they were able to heat up, increasing the temperature up to 42°C in a period of time lower than 10 minutes.

The synthesis of Ba2+-doped multiferroic BiFeO3 nanoparticles using co-precipitation method in the presence of various surfactants and the investigation of structural and magnetic features

In this paper, doped bismuth ferrite nanoparticles with barium (Bi[Formula: see text]Ba[Formula: see text]FeO[Formula: see text], [Formula: see text] = 0.1, 0.15, 0.2) were synthesized by co-precipitation method in the presence of various surface activators. Structural properties, magnetic properties and the size of synthesized nanoparticles were investigated by different techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), dynamic light scattering (DLS) and vibration sample magnetometry (VSM). The data obtained from XRD analysis showed a phase shift from rhombohedral to tetragonal structure by the enhancement of Barium amount in Bismuth ferrite structure. The results of TEM exhibit that the size of particles are 10 nm in average for the synthesized Bi[Formula: see text]Ba[Formula: see text]FeO[Formula: see text] and SEM analysis clarifies the uniform shape of particles which confirms the benign purity of the obtained material. VSM analysis shows that the best magnetic function will be observed when stoichiometric amount of Barium (Bi[Formula: see text]Ba[Formula: see text]FeO[Formula: see text] is [Formula: see text] = 0.15. The effect of diverse surface activators including Triton X-100, polyvinyl alcohol (PVA), sodium dodecyl sulfate (SDS), and cetyl trimethylammonium bromide (CTAB) was studied in the synthesis of Bi[Formula: see text]Ba[Formula: see text]FeO[Formula: see text] nanoparticles and CTAB presented the best effect on the magnetic properties of these nanoparticles.

Preparation of Fe3O4/Reduced Graphene Oxide Nanocomposites with Good Dispersibility for Delivery of Paclitaxel

The Fe3O4/reduced graphene oxide (Fe3O4/RGO) nanocomposites with good dispersibility were synthesized for targeted delivery of paclitaxel (PTX). Firstly, the superparamagnetic Fe3O4/functional GO nanocomposites were prepared via hydrothermal method in which GO sheets were modified by surfactant wrapping. The Fe3O4/RGO nanocomposites were successively prepared through the reduction of graphene oxide. The products were investigated by Fourier-transform infrared spectrum, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and vibration sample magnetometry. It was found that spherical Fe3O4 nanoparticles were uniformly anchored over the RGO matrix and the nanocomposites were superparamagnetic with saturation magnetization (Ms) of 9.39 emu/g. Then PTX was loaded onto Fe3O4/RGO nanocomposites, and the drug loading capacity was 67.9%. Cell viability experiments performed on MCF-7 demonstrated that the Fe3O4/RGO-loaded PTX (Fe3O4/RGO/PTX) showed cytotoxicity to MCF-7, whereas the Fe3O4/RGO displayed no obvious cytotoxicity. The above results indicated that Fe3O4/RGO/PTX nanocomposites had potential application in tumor-targeted chemotherapy.

Adsorption of C.I. Reactive Red 228 and Congo Red dye from aqueous solution by amino-functionalized Fe3O4 particles: kinetics, equilibrium, and thermodynamics

A magnetic adsorbent was synthesized by γ-aminopropyltriethoxysilane (APTES) modification of Fe3O4 particles using a two-step process. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometry were used to characterize the obtained magnetic adsorbent. EDS and XPS showed that APTES polymer was successfully introduced onto the as-prepared Fe3O4/APTES particle surfaces. The saturation magnetization of the magnetic adsorbent was around 65 emu g−1, which indicated that the dye can be removed fast and efficiently from aqueous solution with an external magnetic field. The maximum adsorption capacities of Fe3O4/APTES for C.I. Reactive Red 228 (RR 228) and Congo Red (CR) were 51.4 and 118.8 mg g−1, respectively. The adsorption of C.I. Reactive Red 228 (RR 228) and Congo Red (CR) on Fe3O4/APTES particles corresponded well to the Langmuir model and the Freundlich model, respectively. The adsorption processes for RR 228 and CR followed the pseudo-second-order model. The Boyd's film-diffusion model showed that film diffusion also played a major role in the studied adsorption processes for both dyes. Thermodynamic study indicated that both of the adsorption processes of the two dyes are spontaneous exothermic.