Cell damage induced by asbestos similar particles

The presence, in nature, of asbestos similar particles, highly toxic and potentially cancerogenic for human healthy is well known (1). Inhalation of the fibrous form of erionite, has been shown to cause effects compared to those observed with mineral fibers classified as ‘‘asbestos,’’ including malignant mesothelioma, a disease typically associated with occupational and environmental exposures to asbestos (2). In this work various zeolite materials have been considered because of their suspected carcinogenic activity and, the possible interactions occurring between asbestiform fibers and U937 cell, a human hemopoietic cell line, have been evaluated. Chemical and morpho-functional analyses have been carried out, both to characterize fiber structure and cell response. Cells showed the ability to internalize the minerals, as observed after TEM analyses. With zeolite exposure time increasing, a diffuse cell damage with features of apoptotic and necrotic death can be evidenced (3). These findings suggest that the fibrous form of scolecite or offretite too can be considered potentially toxic for cell culture in vitro

Cationic Imidazolium Polythiophenes: Effects of Imidazolium-Methylation on Solution Concentration-Driven Aggregation and Surface Free Energy of Films Processed from Solvents with Different Polarity

Cationic imidazolium-functionalized polythiophenes with single- or double-methylation of the imidazolium ring were used to study the impact of imidazolium-methylation on (i) the solution concentration-driven aggregation in the presence of paramagnetic probes with different ionic and hydrophobic constituents and (ii) their surface free energy (SFE) as spin-coated films deposited on plasma-activated glass. Electron paramagnetic resonance spectroscopy shows that the differences in film structuration between the polymers with different methylations originate from the early stages of aggregation. In the solid state, higher degree of imidazolium-methylation generates smaller values of total SFE, gamma S, (by around 2 mN/m), which could be relevant in optoelectronic applications. Methylation also causes a decrease in the polar contribution of gamma S (gamma Sp), suggesting that methylation decreases the polar nature of the imidazolium ring, probably due to the blocking of its H-bonding capabilities. The values of gamma S obtained in the present work are similar to the values obtained for doped films of neutral conjugated polymers, such as polyaniline, poly(3-hexylthiophene), and polypyrrole. However, imidazolium-polythiophenes generate films with a larger predominance of the dispersive component of gamma S (gamma Sd), probably due to the motion restriction in the ionic functionalities in a conjugated polyelectrolyte, in comparison to regular dopants. The presence of 1,4-dioxane increases gamma Sp, especially, in the polymer with larger imidazolium-methylation (and therefore unable to interact through H-bonding), probably by a decrease of the imidazolium-glass interactions. Singly-methylated imidazolium polythiophenes have been applied as electrode selective ("buffer") interlayers in conventional and inverted organic solar cells, improving their performance. However, clear structure-function guidelines are still needed for designing high-performance polythiophene-based interlayer materials. Therefore, the information reported in this work could be useful for such applications

Dendronized Anionic Gold Nanoparticles: Synthesis, Characterization and Antiviral Activity

Anionic carbosilane dendrons decorated with sulfonate functions and with a thiol moiety at the focal point have been used to synthesize water soluble gold nanoparticles (AuNPs) by direct reaction of dendrons, gold precursor and reducing agent in water and also by place-exchange reaction. These nanoparticles have been characterized by nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), UV, elemental analysis, and Z potential. Also, the interacting ability of the anionic sulfonate functions was investigated by electron paramagnetic resonance (EPR) using copper(II) as a probe. It was found that the different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups to be complexed by copper(II). Toxicity assays of AuNPs showed that those produced by direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV-1 infection was higher for dendronized AuNPs than for dendrons.Ministerio de Economía y EmpresaComunidad de MadridUniversidad de Alcal

Analysis of Volatile Aromatic Compounds in Heavy Fuel Oils Using Purge and Trap Extraction and A Gas Chromatographic-Mass Spectrometric Technique

The volatile fraction of heavy fuel oils used in thermal power plants is characterized by the presence of trace amounts of potentially carcinogenic compounds, i.e. benzene and toluene, ethylbenzene and the xylenes (BTEX). In this paper, an original methodology for the determination of these compounds in such a complex matrix is presented. It consists of a capillary gas chromatographic-quadrupole mass spectrometric method preceded by the extraction and enrichment of the substituted benzenes by using a “purge and trap” technique. Results obtained analyzing heavy fuel oil actual samples are reported as well

EPR, TEM and cell viability study of asbestiform zeolite fibers in cell media

tHuman monocyte U937 cell line was used as a model to verify the toxicity of erionite and offretiteasbestiform zeolite fibers. As a presumed non-toxic reference, a fibrous scolecite zeolite was also used.To analyze the process of fiber ingestion into cells and the cells-fibers interactions, a spin-probe electronparamagnetic resonance (EPR) analysis was performed supported by transmission electron microscopy(TEM) and cell viability measurements as a function of the incubation time. Erionite fibers were fastinternalized in the membrane mainly as aggregates with radical-solution drops trapped inside, and werefound in the cytosol and at the nucleus. In 24 h, first erionite fibers rich in sodium and potassium, and thencalcium-rich erionite fibers, induced cell necrosis. The offretite fibers formed rounding electron-densefilaments which transformed in curved filaments, initially perturbing the cell structure and interacting atthe external surface more than erionite fibers. Such interactions probably diminished the toxic effect ofoffretite on cells. Interestingly, the presumed non-toxic scolecite fibers were partially internalized, induc-ing formation of swollen mitochondria and squared cells. Overall, the toxic effect of the fibrous zeoliteswas related to fiber morphology, chemical distribution of sites, structural variations and formation ofaggregates

Electron paramagnetic resonance and transmission electron microscopy study of the interactions between asbestiform zeolite fibers and model membranes

Different asbestiform zeolite fibers of the erionite (termed GF1 and MD8, demonstrated carcinogenic) and offretite (termed BV12, suspected carcinogenic) families were investigated by analyzing the electron paramagnetic resonance (EPR) spectra of selected surfactant spin probes and transmission electron microscopy (TEM) images in the presence of model membranes—cetyltrimethylammonium (CTAB) micelles, egg-lecithin liposomes, and dimyristoylphosphatidylcholine (DMPC) liposomes. This was undertaken to obtain information on interactions occurring at a molecular level between fibers and membranes which correlate with entrance of fibers into the membrane model or location of the fibers at the external or internal membrane interfaces. For CTAB micelles, all fibers were able to enter the micelles, but the hair-like structure and chemical surface characteristics of GF1 modified the micelle structure toward a bilayer-like organization, while MD8 and BV12, being shorter fibers and with a high density of surface interacting groups, partially destroyed the micelles. For liposomes, GF1 fibers partially penetrated the core solution, but DMPC liposomes showed increasing rigidity and organization of the bilayer. Conversely, for MD8 and BV12, the fibers did not cross the membrane demonstrating a smaller Q1 membrane structure perturbation. Scolecite fibers (termed SC1), used for comparison, presented poor interactions with the model membranes. The carcinogenicity of the zeolites, as postulated in the series SC1<BV12<MD8<GF1, may be related to the structural modifications of the model membranes when interacting with these zeolite fibers

Characterization of the Surface Interacting Ability of Carbon Black by Means of Electron Paramagnetic Resonance Analysis of Adsorbed Cu2+, Supported by Surface Analysis and Atomic Absorption

Electron paramagnetic resonance (EPR) has been used to investigate the adsorption capability and the surface interacting ability towards Cu(II) solutions (CuCl2, Cu(NO3)(2), CuSO4 in water or ethanol) of various carbon blacks, both graphitized and ungraphitized, selected on the basis of the surface area, namely, Carbograph1 (area = 100 m(2)/g), Carbograph4 (area=210 m(2)/g), and Carbograph5 (area=560 m(2)/g), which were indicated as C1g, C4g, C5g (g = graphitized), and C1ng, C4ng, C5ng (ng = ungraphitized). The EPR analysis was supported by surface analysis, for evaluating the surface area, the pore volume and the porosity, and by atomic absorption to obtain the adsorbed Cu(If) amounts. Graphitization provokes a decrease in surface area, but C1g, at low surface area, showed a unexpected increase of the adsorption ability ascribed to the formation of new surface porosity closed by graphite layers. The carbon samples showed a broad unresolved EPR signal due to mobile unpaired electrons in the carbon matrix. Graphitized samples presented a narrower signal than ungraphitized samples, which increases in width with the increase in surface area (with the exception of C5ng due to the high exposition of the wide surface to oxydizing external agents) and upon prolonged thermal treatment. The signal intensity of the carbon paramagnetic centers decreases upon Cu(II) adsorption. Computer aided analysis of the EPR spectra of the solids after Cu(II) adsorption allowed to extract structural information on the Cu-surface site complexes. The Cu2+ ions coordinated with surface polar sites, mainly oxygenated. Adsorption depends on the different Cu(II) salts, caused by the salt solubility and the interacting ability of the counter-ion. In several cases the solutions concentrated in the carbon porosity leading to precipitation of the salt. Ethanol solutions are more adsorbed at the carbon surface than water solutions; Cu(II) partially retains its solvation shell and partially presents electron transfer to the carbon surface. Adsorption is favored to ungraphitized carbons with respect to the graphitized ones due to both the higher surface area, and the higher hydrophilicity of the surface. In summary, these carbon powders, widely used for chromatographic applications, show an adsorption capability towards Cu(11) solutions higher than expected due to both a definite porosity, and the presence of polar groups which are not eliminated with chemical surface treatments. (C) 2002 Elsevier Science B.V. All rights reserved