Scaffolds with Magnetic Nanoparticles for Tissue Stimulation

Magnetic nanoparticles (MNPs) have been used in several medical applications, including targeted hyperthermia, resonance tomography, diagnostic sensors, and localized drug delivery. Further applications of magnetic field manipulation through MNPs in tissue engineering have been described. The current study aims to develop tissue-engineered polymeric scaffolds with incorporated MNPs for applications that require stimulation of the tissues such as nerves, muscles, or heart. Electrospun scaffolds were obtained using 14%w/v polycaprolactone (PCL) in 2,2,2-Trifluoroethanol (TFE) at concentrations of 5% & 7.5%w/v of dispersed MNPs (iron oxide, Fe3O4, or cobalt iron oxide, CoFe2O4). Scaffolds were analyzed using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, uniaxial tensile testing, and cell seeding for biocompatibility. Human bone marrow mesenchymal stem cells (bmMSCs) were seeded on the scaffolds. Biocompatibility was assessed by metabolic activity with Resazurin reduction assay on day 1, 3, 7, 10. Cell-cell and cell-scaffold interactions were analyzed by SEM. Electrospun scaffolds containing MNPs showed a decrease in fiber diameter as compared to scaffolds of pure PCL. The maximum force increases with the inclusion of MNPs, with higher values revealed for iron oxide. The metabolic activity decreased with MNPs, especially for cobalt iron oxide at a higher concentration. On the other hand, the cells developed good cell-scaffold and cell-cell interactions, making the proposed scaffolds good prospects for potential use in tissue stimulation.

Synthesis of Cobalt Iron Oxide Doped by Chromium Using Sol-Gel Method and Application to Remove Malachite Green Dye

In the current paper, the nanoparticles of cobalt iron oxide doped by chromium (CIC) of (CrxCoFe2-xO4) formula were prepared by sol-gel method using the nitrate salts of the elements composed of this nanomaterial. The characteristic properties of CIC nanoparticles prepared were determined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) in addition to scanning electron microscopy (SEM) and also examination of the surface area (BET). These tests showed that the CIC nanoparticle prepared was in a pure phase, in addition to having various functional groups; moreover their structural framework includes multiple pores, which was the reason for the high surface area, reached to 223.36 m2.g-1. The prepared CIC nanoparticle was applied as an adsorbent to recover the malachite green dye from aqueous contaminated solutions in a batch mode adsorption unit and under different operating conditions. Designing factors used to determine the efficiency of the CIC as an adsorption media for the organic dye included the acidic function (pH), contact time and amount of nanomaterial CIC. The obtained practical results showed that the removal efficiency of the malachite green dye using CIC nanoparticle was 88.519% at 50 ppm of the initial concentration of the contaminated solution and that the percentage removal was directly proportional to the amount of adsorbent, contact time and acidic function.

Preparation and physical characterization of cobalt iron oxide magnetic nanoparticles loaded polyvinyl alcohol

A solvent thermal method which depends on a thermal process under critical temperature and pressure was used to prepare cobalt iron oxide magnetic nanoparticles with a molar ratio 2. The prepared particles were in the form of nanoparticles with diameter ranging from 5 to 10 nm and with amorphous structure. Magnetic hysteresis behavior with saturation magnetization 36.31 emu/g and coercivity 4 Oe were observed for the nanoparticles. Polyvinyl alcohol was loaded with different concentrations of cobalt iron oxide nanoparticles using casting technique. Hysteresis loops for the polymer films were observed and both the saturation magnetization and coercivity were increased from 0.36 to 16.03 emu/g and 115 to 293 Oe for samples containing 5 and 20 wt% of nanoparticles, respectively. The elastic modulus of films was increased from 2.7 to 4.9 GPa for unloaded and loaded samples with 20 wt%, respectively. The storage modulus of the polymer films was found to obey the percolation behavior.

Integration of adsorption and catalysis active sites in cobalt iron oxide nanorods for excellent performance Li-S Battery with a wide temperature range

Whether Li-S batteries can be worked in a wider temperature range is particularly important. Here, we report a micronano structure CoFe2O4 rods accompanied with both catalytic site (Co) and adsorption...

Characterization and Nanofluid Stability of CoFe2O4-APTES and CoFe2O4-PVA Nanoparticles

Nanofluid contains nanoparticles that enhanced the property of the base fluid. However, the separating layer between the nanoparticles and base fluids may interfere the nanofluids performance. Studies have been made that surface modification of nanoparticles may improve the dispersion of nanoparticles in base fluids. This paper reports the study of the colloidal stability of surface modified nanoparticles using a polymer and an amino-silane. The nanoparticles were prepared by one-step and two-step methods using cobalt iron oxide nanoparticles with brine solution and deionized water as the base fluids. Functionalization by surface modification of the nanoparticles to enhance the nanofluids stability was carried out using (3-aminopropyl) triethoxysilane (APTES) and polyvinyl alcohol (PVA). Characterization using Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and X-ray Powder Diffraction (XRD) were performed to study the functionality and morphology of the synthesized nanoparticles. The extra IR peaks such as Si-O-Si at 1063 cm-1 for CoFe2O4-APTES and C=O at 1742 cm-1 for CoFe2O4-PVA showed that there are additional elements in the cobalt ferrite due to functionalization. The size of synthesized CoFe2O4-APTES ranged between 15.99 nm to 26.89 nm while CoFe2O4-PVA is from 25.70 nm to 54.16 nm. The stability of the nanofluid were determined via zeta potential measurements. CoFe2O4-APTES nanofluid has zeta potential of -35.7 mV compared to CoFe2O4-PVA at -15.5 mV.

Microwave Absorbing properties of metal functionalized-CNT-polymer composite for stealth applications

In this study, we report on the electrical properties of multi-wall carbon nanotubes (MWCNT) composites functionalized with metal or metal alloy oxides and embedded in a polyurethane matrix to develop a lightweight material for microwave absorption and shielding. The CNT nanoparticles are functionalized with metallic oxides such as Cobalt oxide, Iron oxide, and Cobalt Iron oxide, at three different concentrations. Metallic oxides are used at 5%, 10%, and 20% concentration of the total CNT percentage weight. The resulting functionalized CNT is mixed with polyurethane polymer at 5% wt of the total composite weight. Three sets of cylindrical samples are developed, and each set contains three different metal oxide concentrations. The dielectric properties of the nine developed samples are obtained by measuring their permittivity spectra using an open-ended coaxial probe technique in the spectral range 5–50 GHz. The absorption efficiency of the composites is then obtained by calculating the reflection loss at normal incidence. The results show that the spectral range of absorption can be tuned by changing the CNT concentration, and the material thickness. Functionalized CNT with different alloyed metal oxides enhanced the absorption efficiency of the polyurethane/CNT composites. Such functionalized composites can be used to replace the common heavyweight materials used for microwave applications.