Nicotinic Acid Coated Magnetite Nanorods Evaluation by Lipid Profile Analysis and Genetic Tests

In our present work some biological tests were carried out to assess the biocompatibility of nicotinic acid coated magnetite nanorods. Pure and coated nanorods were injected intraperitoneally to cholesterol fed mice with dose values of 25, 50 mg/Kg. Investigations were done on treated mice with/without exposure to low frequency electromagnetic field (EMF) and samples were collected fourteen days post treatment. Toxicological effects were evaluated using Micronucleus and DNA fragmentation analysis. The results indicated that low dose (25 mg/Kg) nicotinic acid coated nanorods had insignificant toxicological effects in comparison to that of control group. Lipid profile analysis and gene expression of atheroprotective (eNOS) and atherogenic (p65) genes were also investigated. It was found that experimental groups treated with low dose nicotinic acid coated magnetite nanorods and exposed to EMF showed interesting alterations in mice lipid profile. As a result, an insignificant but slight increase in gene expression levels of eNOS and a significant decrease in p65 gene expression were observed. Our study suggests that our proposed magnetic nanosystem in combination with EMF has good biocompatibility and can be a potential drug precursor with therapeutic values.

Hybrid Plasmonic Nanostructures

Plasmonic hybrid nanostructure including Semiconductor-metallic nanoparticles, and graphene-plasmonic nanocomposites have great potential to be used as photocatalyst for hydrogen production and for photodegradation of organic waste. Also, they are potential candidate as active materials in photovoltaic devices. Plasmonic-magnetic nanocomposites could be used in photothermal therapy and biomedical imaging. This chapter will focus on the environmental impact of these materials and their in-vitro and in-vivo toxicity. In addition, the applications of these hybrid nanostructures in energy and environment will be discussed in details.

Hybrid magnetic–plasmonic nanocomposite: embedding cobalt clusters in gold nanorods

Preparation of Plasmonic–magnetic hybrid nanorods via modified seed mediated method: using cobalt seeds instead of gold to prepare Au–Co NRs.

Buried nanoantenna arrays: versatile antireflection coating

Reflection is usually a detrimental phenomenon in many applications such as flat-panel-displays, solar cells, photodetectors, infrared sensors, and lenses. Thus far, to control and suppress the reflection from a substrate, numerous techniques including dielectric interference coatings, surface texturing, adiabatic index matching, and scattering from plasmonic nanoparticles have been investigated. A new technique is demonstrated to manage and suppress reflection from lossless and lossy substrates. It provides a wider flexibility in design versus previous methods. Reflection from a surface can be suppressed over a narrowband, wideband, or multiband frequency range. The antireflection can be dependent or independent of the incident wave polarization. Moreover, antireflection at a very wide incidence angle can be attained. The reflection from a substrate is controlled by a buried nanoantenna array, a structure composed of (1) a subwavelength metallic array and (2) a dielectric cover layer referred to as a superstrate. The material properties and thickness of the superstrate and nanoantennas' geometry and periodicity control the phase and intensity of the wave circulating inside the superstrate cavity. A minimum reflectance of 0.02% is achieved in various experiments in the mid-infrared from a silicon substrate. The design can be integrated in straightforward way in optical devices. The proposed structure is a versatile AR coating to optically impedance matches any substrate to free space in selected any narrow and broadband spectral response across the entire visible and infrared spectrum.

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.

Genotoxicity evaluation of nanomaterials: dna damage, micronuclei, and 8-hydroxy-2-deoxyguanosine induced by magnetic doped CdSe quantum dots in male mice

Quantum dots (QDs) are a novel class of inorganic fluorophores which are gaining widespread recognition as a result of their exceptional photophysical properties and their applications as a biomarker and in molecular biomedical imaging. The aim of this study was to evaluate the in vivo genotoxicity in mice exposed to CdSe quantum dots of average size 5.0 ± 0.2 nm and CdSe doped with 1% cobalt ions of similar size. The quantum dots are surface modified using mercaptoacetic acid (MAA) in order to be biocompatible and water-soluble. The MAA-QDs were given to the mice orally at doses of 500, 1000, and 2000 mg/kg by weight of MAA-QDs. Bone marrow and liver samples were collected after two and seven days of treatment. The results indicated that after two days of treatment, the high dose of doped MAA-QDs was significantly able to induce DNA damage, formation of micronuclei (MNs), and generation of DNA adduct (8-hydroxy-2-deoxyguanosine, 8-OHdG). However, increasing DNA damage and the frequency of MNs formation as well as the generation of DNA adducts were observed with both the undoped MAA-QDs (2000 mg/kg) and doped MAA-QDs (1000 and 2000 mg/kg) after seven days of treatment. The results of our study indicate that exposure to high doses of pure MAA-QDs or MAA-QDs doped with cobalt has the potential to cause indirect in vivo genetic damage, which may be attributed to free radical-induced oxidative stress in mice.

Effects of surface topography on magnetization reversal of magnetic thin films

The influence of the created surface roughness on the coercivity of magnetic thin films has been investigated. The magnetic thin films (CoFe and alternatively NiFe) are sputtered on top of smooth substrates that were previously covered with an array of considerably rougher lines with one of these materials Pt, Cu, CoFe, and NiFe. The lines have been patterned using optical lithography into arrays that are deposited with different thicknesses varying between 5 nm-15 nm. The lines have been designed to have a very rough edge and seated in two different angles relative to the wafer edge (zero and 45 degrees). Magneto-optic Kerr effect (MOKE) measurements showed two distinct switching fields in the hysteresis loops that are due to magnetic domain wall trapping created by the surface roughness. The magnetization reversal showed a strong dependence on the height, the orientation angle, and the material's type of the created surface roughness (the lines).

Tunneling anisotropic magnetoresistance: a spin-valve-like tunnel magnetoresistance using a single magnetic layer

We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material.

Enhanced asymmetric magnetization reversal in nanoscale Co/CoO arrays: competition between exchange bias and magnetostatic coupling

Magnetization reversal was studied in square arrays of square Co/CoO dots with lateral size varying between 200 and 900 nm. While reference nonpatterned Co/CoO films show the typical shift and increased width of the hysteresis loop due to exchange bias, the patterned samples reveal a pronounced size dependence. In particular, an anomaly appears in the upper branch of the magnetization cycle and becomes stronger as the dot size decreases. This anomaly, which is absent at room temperature in the patterned samples, can be understood in terms of a competition between magnetostatic interdot interaction and exchange anisotropy during the magnetic switching process.

Potent graft antitumor effect in natural killer-resistant disseminated tumors by transplantation of interleukin 2-activated syngeneic bone marrow in mice

The current study is a continuation of our previous work showing that bone marrow activated in interleukin 2 has antitumor and antiviral activity in vitro. The antitumor efficacy of IL-2-activated bone marrow cells in vivo was assessed here. Our results indicated that bone marrow cells activated in IL-2 for 3 days (ABM) have antitumor activity in vivo and cause significant tumor regression in mice being treated with ABM and concurrent i.p. administration of IL-2. In mice also bearing larger tumor burdens, those receiving ABM and i.p. IL-2 showed the most significant tumor regression. The ABM seem to be more potent than conventional IL-2-activated spleen lymphokine-activated killer cells. In studies done using lower dosages of IL-2 or log lower number of cells, the ABM caused more significant tumor regression than lymphokine-activated killer cells. We also assessed the antitumor efficacy of short term (1 day) IL-2-activated bone marrow, the short term-activated bone marrow being preferred in bone marrow, transplantation because of the minimum amount of cells lost due to its shorter incubation period. We also showed that short term-activated bone marrow caused tumor regression similar to ABM and could reconstitute lethally irradiated mice similar to fresh bone marrow. Therefore, the biomodulation of bone marrow cells could be used as an active therapeutic tool in autologous bone marrow transplantation, producing graft versus tumor effects without any graft versus host effect.

Therapy of disseminated NK-resistant tumor by the synergistic effects of recombinant interleukin-2 and tumor necrosis factor

Tumor necrosis factor and interleukin-2 each in recombinant form have antitumor activity against established tumors if used in high enough dosages. The problem associated with such high dosages is the high degree of toxicity and expense encountered. Therefore, this study was undertaken to look at the antitumor efficacy of these two lymphokines when used together at dosages well below the toxic levels. Our results using recombinant human interleukin-2 (IL-2) and recombinant human tumor necrosis factor (TNF) against established methylcholanthrene-induced fibrosarcoma (MCA sarcoma) pulmonary metastases showed that TNF and IL-2 therapy at low nontoxic dosages alone did not produce significant tumor regression, but when combined at the same dosage synergize producing significant antitumor effects in mice induced with MCA sarcoma. This was also evident from histopathological examination of the lungs where the maximum tumor reduction along with the maximum lymphocytic infiltration into tumor was seen when TNF and IL-2 were combined. In this tumor regression, inherent immunity of the treated mice was needed, since in those mice in which we induced immunosuppression by using radiation, tumor regression was not seen when TNF and IL-2 therapy was combined in the doses efficacious in immunocompetent mice. Tumor regression is also dependent on the sequence of administration of IL-2 and TNF, since when IL-2 was administered before TNF, the tumor regression was more significant than when TNF was administered before IL-2 or when both were administered simultaneously to mice with established pulmonary tumors. Therefore the synergistic effect of IL-2 and TNF could be used as an efficacious but inexpensive and nontoxic alternative to therapy with lymphokine activated killer (LAK) cells + IL-2.