Synthesis and Characterization of Magnetic Elastomer based PEG-Coated Fe3O4from Natural Iron Sand

Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide

The increasing demand for polymer composites with novel or improved properties requires novel fillers. To meet the challenges posed, nanofillers such as graphene, carbon nanotubes, and titanium dioxide (TiO2) have been used. In the present work, few-layer graphene (FLG) and iron oxide (Fe3O4) or TiO2 were used as fillers in a room-temperature-vulcanized (RTV) silicone rubber (SR) matrix. Composites were prepared by mixing RTV-SR with nanofillers and then kept for vulcanization at room temperature for 24 h. The RTV-SR composites obtained were characterized with respect to their mechanical, actuation, and magnetic properties. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to investigate the composite raw materials and finished composites, and X-ray photoelectron spectroscopy (XPS) analysis was used to study composite surface elemental compositions. Results showed that mechanical properties were improved by adding fillers, and actuation displacements were dependent on the type of nanofiller used and the applied voltage. Magnetic stress-relaxation also increased with filler amount and stress-relaxation rates decreased when a magnetic field was applied parallel to the deformation axes. Thus, this study showed that the inclusion of iron oxide (Fe3O4) or TiO2 fillers in RTV-SR improves mechanical, actuation, and magnetic properties.

In vitro cytotoxicity studies of smart pH-sensitive lamivudine-loaded CaAl-LDH magnetic nanoparticles against Mel-Rm and A-549 cancer cells

In this study, an effective nano-drug delivery system was prepared by the co-precipitation method via two steps; the preparation of Fe₃O₄ magnetic nanoparticles and its surface modification with layered double hydroxide (LDH) and loading lamivudine on this nanocarrier (Fe₃O₄@CaAl-LDH@Lamivudine). The developed nanoparticles (NPs) were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Fourier-transformed infrared spectroscopy, vibrating-sample magnetometry, thermogravimetric analysis, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. The prepared system demonstrated an average size of 130 nm. Also, the drug entrapment efficiency was estimated at ∼70%. In vitro, drug release investigations showed a controlled and pH-dependent lamivudine release over 300 min. The in vitro cytotoxic activity of Fe₃O₄@CaAl-LDH@Lamivudine NPs was explored against Mel-Rm and A-549 cancer cell lines in comparison with lamivudine and nanocarrier using lactate dehydrogenase colorimetric and MTT assay. The results of the MTT assay revealed that the Fe₃O₄@CaAl-LDH@Lamivudine NPs significantly inhibited the proliferation of Mel-Rm and A-549 cells in a dose-dependent manner. The influences of Fe₃O₄@CaAl-LDH@Lamivudine on the cancer cell lines by different therapeutic investigation illustrated the remarkable effect in comparison with free drug. Finally, the achieved consequences confirm the anticancer properties of Fe₃O₄@CaAl-LDH@Lamivudine and indicate that they may be a cost-effective substitute in the treatment of lung and skin cancer.Communicated by Ramaswamy H. Sarma.

Synthesis of magnetite/silica nanocomposites from natural sand to create a drug delivery vehicle

In this study, we report the synthesis of the magnetite/silica nanocomposites and their structural and functional groups, magnetic properties, morphology, antimicrobial activity, and drug delivery performance. The X-ray diffraction characterization showed that magnetite formed a spinel phase and that silica formed an amorphous phase. The particle sizes of magnetite increased from 8.2 to 13.2 nm with increasing silica content, and the particles were observed to be superparamagnetic. The nanocomposites tended to agglomerate based on the scanning electron microscopy images. The antimicrobial activity of the magnetite/silica nanocomposites revealed that the increasing silica content increased the inhibition zones by 74%, 77%, and 143% in case of Gram-positive bacteria (B. subtilis), Gram-negative bacteria (E. coli), and fungus (C. albicans), respectively. Furthermore, doxorubicin was used as the model compound in the drug loading and release study, and drug loading was directly proportional to the silica content. Thus, the increasing silica content increased the drug loading owing to the increasing number of OH- bonds in silica, resulting in strong bonds with doxorubicin. Based on this study, the magnetite/silica nanocomposites could be applied as drug delivery vehicles.

Magnetic Particle Filled Elastomeric Hybrid Composites and Their Magnetorheological Response

The magnetorheological (MR) elastomer as a hard and soft hybrid functional material, a composite material consisting of magnetic hard particles embedded in elastomeric soft matrix, is a branch of MR materials that are functional smart materials rapidly responding to external magnetic fields. These tunable properties of MR elastomers facilitate a variety of applications. In this brief review paper, in addition to general information on the MR elastomers, recent research not only on a wide variety of MR elastomeric systems focusing on various magnetic particles, elastomeric matrices, additives and particle modification methods, but also on their characteristics including MR properties from dynamic oscillation tests is covered along with their mechanical properties such as the Payne effect, tensile strength and engineering applications.