Spray Deposited Nanocrystalline ZnO Transparent Electrodes: Role of Precursor Solvent

Nanocrystalline ZnO thin films were deposited by intermittent spray pyrolysis using different alcoholic and aqua-alcoholic precursor solvents. The XRD analysis reveals the polycrystallinity of hexagonal wurtzite type ZnO films with preferred c-axis orientation along [002] direction. The polycrystallinity increased due to use of aqua-alcoholic precursor solvent. The crystallite size was found to vary from 41.7 nm to 59.4 nm and blue shift in band-gap energy (3.225 eV to 3.255 eV) was observed due to aqua-alcoholic to alcoholic precursor solvent transition. The films deposited using alcoholic precursor solvent exhibited high transmittance (> 92 %) with low dark resistivity (10 – 3 Ω·cm) as compared to aqua-alcoholic precursor solvent. The effect of precursor solvent on resistivity, carrier concentration (η – /cm3), carrier mobility (μ – cm2V – 1s – 1), sheet resistance (Ω/) and figure of merit (ΦTC) is also reported. We recommend ethanol or methanol as a superior precursor solvent over aqua-alcoholic precursor solvent for deposition of device quality ZnO thin films

Biocompatibility of Fe(3)O(4) nanoparticles evaluated by in vitro cytotoxicity assays using normal, glia and breast cancer cells

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cytotoxicity and genotoxicity of size-fractionated iron oxide (magnetite) in a549 human lung epithelial cells: role of ROS, JNK, and NF-κB

Airborne particulate matter (PM) of varying size and composition is known to cause health problems in humans. The iron oxide Fe₃O₄ (magnetite) may be a major anthropogenic component in ambient PM and is derived mainly from industrial sources. In the present study, we have investigated the effects of four different size fractions of magnetite on signaling pathways, free radical generation, cytotoxicity, and genotoxicity in human alveolar epithelial-like type-II cells (A549). The magnetite particles used in the exposure experiments were characterized by mineralogical and chemical techniques. Four size fractions were investigated: bulk magnetite (0.2–10 μm), respirable fraction (2–3 μm), alveolar fraction (0.5–1.0 μm), and nanoparticles (20–60 nm). After 24 h of exposure, the A549 cells were investigated by transmission electron microscopy (TEM) to study particle uptake. TEM images showed an incorporation of magnetite particles in A549 cells by endocytosis. Particles were found as agglomerates in cytoplasm-bound vesicles, and few particles were detected in the cytoplasm but none in the nucleus. Increased production of reactive oxygen species (ROS), as determined by the 2′,7′-dichlorfluorescein-diacetate assay (DCFH-DA), as well as genotoxic effects, as measured by the cytokinesis block-micronucleus test and the Comet assay, were observed for all of the studied fractions after 24 h of exposure. Moreover, activation of c-Jun N-terminal kinases (JNK) without increased nuclear factor kappa-B (NF-κB)-binding activity but delayed IκB-degradation was observed. Interestingly, pretreatment of cells with magnetite and subsequent stimulation with the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFα) led to a reduction of NF-κB DNA binding compared to that in stimulation with TNFα alone. Altogether, these experiments suggest that ROS formation may play an important role in the genotoxicity of magnetite in A549 cells but that activation of JNK seems to be ROS- independent