B. A. Albiss

Magnetic nanoparticles sensitize MCF-7 breast cancer cells to doxorubicin-induced apoptosis

BackgroundResistance of breast cancer cells to the available chemotherapeutics is a major obstacle to successful treatment. Recent studies have shown that magnetic nanoparticles might have significant application in different medical fields including cancer treatment. The goal of this study is to verify the ability of magnetic nanoparticles to sensitize cancer cells to the clinically available chemotherapy.MethodsThe role of iron oxide nanoparticles, static magnetic field, or a combination in the enhancement of the apoptotic potential of doxorubicin against the resistant breast cancer cells, MCF-7 was evaluated using the MTT assay and the propidium iodide method.ResultsIn the present study, results revealed that pre-incubation of MCF-7 cells with iron oxide nanoparticles before the addition of doxorubicin did not enhance doxorubicin-induced growth inhibition. Pre-incubation of MCF-7 cells with iron oxide nanoparticles followed by a static magnetic field exposure significantly (P < 0.05) increased doxorubicin-induced cytotoxicity. Sensitization with pre-exposure to the magnetic field was dose-dependent where the highest cytotoxicity was seen at 1 tesla. Further experiments revealed that the anti-proliferative effect of this treatment procedure is due to induction of apoptotic cell death.ConclusionsThese results might point to the importance of combining magnetic nanoparticles with a static magnetic field in treatment of doxorubicin-refractory breast cancer cells.

Cerium oxide and iron oxide nanoparticles abolish the antibacterial activity of ciprofloxacin against gram positive and gram negative biofilm bacteria

Metal oxide nanoparticles have been suggested as good candidates for the development of antibacterial agents. Cerium oxide (CeO2) and iron oxide (Fe2O3) nanoparticles have been utilized in a number of biomedical applications. Here, the antibacterial activity of CeO2 and Fe2O3 nanoparticles were evaluated on a panel of gram positive and gram negative bacteria in both the planktonic and biofilm cultures. Additionally, the effect of combining CeO2 and Fe2O3 nanoparticles with the broad spectrum antibiotic ciprofloxacin on tested bacteria was investigated. Thus, minimum inhibitory concentrations (MICs) of CeO2 and Fe2O3 nanoparticles that are required to inhibit bacterial planktonic growth and bacterial biofilm, were evaluated, and were compared to the MICs of the broad spectrum antibiotic ciprofloxacin alone or in the presence of CeO2 and Fe2O3 nanoparticles. Results of this study show that both CeO2 and Fe2O3 nanoparticles fail to inhibit bacterial growth and biofilm biomass for all the bacterial strains tested. Moreover, adding CeO2 or Fe2O3 nanoparticles to the broad spectrum antibiotic ciprofloxacin almost abolished its antibacterial activity. Results of this study suggest that CeO2 and Fe2O3 nanoparticles are not good candidates as antibacterial agents, and they could interfere with the activity of important antibiotics.

Temperature dependence of the vortex pinning enhancement by γ irradiation of Bi1.6Pb0.4Sr2Ca2Cu3O10 polycrystals

Abstract The saturation remanent magnetization M RS , taken to represent the vortex pinning strength, was measured at various temperatures from 4.2 K up to near T c on two similarly prepared polycrystalline samples of B 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3 O 10 (BPSCCO), one of which had been subsequently γ-irradiated. For both samples, the decrease of M RS with rising temperature ( T ) is found to consist of two distinct components, one of which varies linearly with t (=1− T / T c ) up to T c , and the other decays very rapidly, essentially as t β with β just under 10. The γ irradiation is seen to produce a threefold enhancement of the linear- t component, but its major effect is a 10-fold enhancement of the exponential- t β component. The direct connection between M RS and the vortex pinning strength is tested and confirmed by sample-rotational magnetization measurements. Hence, the M RS component whose temperature decay is exponentially rapid can be attributed to a thermal decoupling of vortices from localized pinning sites. The pronounced irradiation-enhancement of this component thus implies that the defects produced by the γ-rays are acting primarily as vortex pinning sites that are effectively very restricted in size.

Hybrid Zinc Oxide Nanorods/Carbon Nanotubes Composite for Nitrogen Dioxide Gas Sensing

This study reports on the synthesis and fabrication of hybrid nanocomposite based on single-walled carbon nanotubes–ZnO nanorods (SWCNT-ZnONR) as resistive gas sensors for NO2 detection. The sensor was prepared using the standard simple and cost-effective hydrothermal process. The sensor was characterized by x-ray diffraction (XRD) and scanning electron microscopy. The findings revealed enhanced porous SWCNT-ZnONR nanocomposites due to the high porosity of the SWCNT. It was also found that the sensor exhibited average response and recovery times of about 70 s and 100 s, respectively. The XRD peak at 26° indicated that the SWCNT pattern was not disturbed, while sensitivity increased with temperature up to 150°C, at which the sensitivity was maximum. Similarly, the sensor sensitivity increased with NO2 concentration at all levels examined. Moreover, the results indicate that the sensor shows significant promise for NO2 gas sensing applications.

Mössbauer and structural studies of Fe0.7−xVxAl0.3 alloys

Abstract We report the Mossbauer and structural studies of the alloy system Fe 0.7− x V x Al 0.3 where x =0, 0.02, 0.06, 0.1, 0.2, and 0.3. X-ray diffraction indicates that all the samples studied have single phase with body center cubic structure. The lattice parameter ( a ) increases with increasing the vanadium concentration. Room temperature Mossbauer studies show magnetic ordering for small values of x and paramagnetic behavior for large values of x . The Mossbauer spectra were fitted by a distribution of magnetic hyperfine fields for small values of x and two singlets were added for large values of x . The relation between the hyperfine field and the isomer shift in the hyperfine field distribution is linear. The average hyperfine field and isomer shift were found to decrease with increasing V concentration. The results are interpreted in terms of local environmental effects on the hyperfine interactions.

Ultraviolet photodetector based on ZnO nanorods grown on a flexible PDMS substrate

A flexible, reproducible, sensitive and low-cost ultraviolet (UV) detector has been fabricated based on zinc oxide (ZnO) nanorods grown on a patterned polydimethylsiloxane (PDMS) substrate. The substrate was seeded with ZnO nanoparticles synthesised via simple low-temperature hydrothermal method using pomegranate peel extract as a reducing agent. The produced ZnO-nanorods/PDMS (ZnO-NR/PDMS) samples were tested for their UV-sensing properties. Samples were characterised using scanning electron microscopy, X-ray diffraction, I–V characteristics, UV-Vis spectroscopy and photoluminescence measurements. The UV photoresponse mechanism of prototype UV detector was analysed. The detector exhibited quite high on/off ratios between photoresponse current and dark current. With the flexible PDMS substrate, the detector photoresponse was tested with and without bending and exhibited a very slight change in the photoresponse current. The detector current–time response was also tested under various UV light intensities for three test cycles to examine the detector stability, hysteresis behaviour and performance. It is anticipated that the fabrication of ZnO-NR/PDMS UV detector may have significant potential application in flexible optoelectronic devices.

Dissipative behavior and γ-irradiation of silver-sheathed Bi1.8Pb0.4Sr2Ca2Cu3Ox tape

Abstract Dissipative mechanisms in Bi 1.8 Pb 0.4 Sr 2 Ca 2 Cu 3 O x tapes were investigated using magnetoresistance measurements and V – I characteristics. A considerable broadening of the resistive transition in applied magnetic field was observed up to a field of 0.5 T. The temperature and magnetic field dependence of the resistance R ( T , B ) were fitted to the Arrhenius relation and from which the magnetic field dependence of the pinning energy U 0 ( B )∼ B − α with α ≈0.9 was derived. The variations of the critical current densities J c with temperature and magnetic field before and after γ-irradiation were also studied. The temperature dependence of J c ( T ) was fitted to the relation J c ( T )∼(1− T / T c ) n with n =1.9 and discussed in terms of thermally activated flux flow (TAFF). However, J c ( B ) results were explained based on the weak links, grain boundaries, and Josephson junctions in which it shows a power law behaviour J c ( B )∼ B −0.5 . At relatively low temperatures and magnetic fields, the critical current density was increased with a γ-irradiation up to a dose of 100 MR.

A prototype Ultraviolet Light Sensor based on ZnO Nanoparticles/Graphene Oxide Nanocomposite Using Low Temperature Hydrothermal Method

A new prototype UV nanosensor using ZnO nanoparticles (NPs)/graphene oxide (GO) nanocomposite (ZnO-NP/GO) on silicon substrate is reported in this paper. The hybrid nanocomposite structure has been developed by an optimized hydrothermal process at low growth temperature (~50 °C). In this hybrid nanosensor, the ZnO nanoparticles act as UV- absorbing and charge carrier generating material, while graphene with its superior electrical conductivity has been used as a charge transporting material. Various nanostructure characterization techniques were intensively utilized including SEM, EDX, XRD, FTIR and UV-VIS. Also, the I-V measurement was employed to evaluate the prototype sensor. The morphological SEM analysis showed that the ZnO-NPs (average diameter of 20 nm) were dispersed evenly on the GO sheets. As well, the EDX spectra confirmed the exact chemical composition of the intended structure. The room temperature UV-VIS measurement revealed an enhanced optical absorption of UV-light at an absorption band centered on 375 nm. The improved optical and electrical properties were observed at an optimum relative concentration of 1:10. Under UV light illumination, the measured I-V characteristic of the prototype detector exhibited a considerable photocurrent increase of the ZnO-NP/GO nanocomposite compared to pristine ZnO nanostructure. These results can be promising for future enhanced UV- sensing applications.

Levitation Force Between Monolayer of Magnetic Particles and Superconducting Plane in Meissner State

We have calculated the levitation force and the interaction energy between a thin monolayer of super-paramagnetic fine ferromagnetic particles system and a large flat superconductor in the Meissner state. Both energy and force depend on the temperature and the levitation height of the monolayer. Our results show that the interaction energy and the levitation force increases as the temperature of the momolayer increases. In the limit of zero Kelvin temperature, we found that our results for the levitation force goes over to the case where all the moments of the fine-particle system are parallel to the superconductor surface, which has the lowest interaction energy.

Effect of γ-irradiation on polycrystalline Tl1Ba2Ca2Cu3Oy superconductor

Specimens of polycrystalline T1 1 Ba 2 Ca 2 Cu 3 O y superconductor (T1-1223) have been irradiated at room temperature by γ-rays. The variations of the normal state resistance, transition width and the critical current densities with γ-irradiation up to about 400 MR were studied. The normal state resistivity ρ(T) increases gradually up to a dose of 100 MR, whereas at higher doses, the effect of irradiation becomes rather negligible. The transition temperature T c decreases slightly and the transition temperature width AT broadens at doses below 100 MR with almost no change at higher doses up to 400 MR. At relatively low temperatures and low γ-doses, the critical current densities J c (T) increase with γ-irradiation, while the effect of γ-irradiation at temperatures very close to T c is rather negligible. Obtained results confirmed the high sensitivity of (T1-1223) superconductor to γ-irradiation at relatively low γ-doses. These results are discussed and explained in terms of the effect of γ-rays on the weak links and Josephson junctions between the grains.