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The incorporation of small amounts of nanofillers in polymeric matrices has enabled new applications in several industrial sectors. The nanofiller dispersion can be improved by modifying the nanomaterial (NM) surface or predispersing the NMs to enhance compatibility. This study evaluates the effect of these compatibilization strategies on migration/release of the nanofiller and transformation of polyamide-6 (PA6), a thermoplastic polymer widely used in industry during simulated outdoors use. Two nanocomposites (NCs) containing SiO2 nanoparticles (NPs) with different surface properties and two multiwalled carbon nanotube (MWCNT) NCs obtained by different addition methods were produced and characterized, before and after accelerated wet aging conditions. Octyl-modified SiO2 NPs, though initially more aggregated than uncoated SiO2 NPs, reduced PA6 hydrolysis and, consequently, NM release. Although no clear differences in dispersion were observed between the two types of MWCNT NCs (masterbatch vs direct addition) after manufacture, the use of the MWCNT masterbatch reduced PA6 degradation during aging, preventing MWCNT accumulation on the surface and further release or potential exposure by direct contact. The amounts of NM released were lower for MWCNTs (36 and 108 mg/m(2)) than for SiO2 NPs (167 and 730 mg/m(2)), being lower in those samples where the NC was designed to improve the nanofiller-matrix interaction. Hence, this study shows that optimal compatibilization between NM and matrix can improve NC performance, reducing polymer degradation and exposure and/or release of the nanofiller.

Cancer cells display an overproduction of reactive oxygen species resulting from an exaggerated intrinsic oxidative stress. However, the concept of deleterious oxidants versus beneficial antioxidants has recently evolved. Indeed, molecules like natural coumarins have shown anti-oxidant or pro-oxidant properties depending on their intracellular concentration. Therefore, we have investigated the structure-activity relationship of a variety of coumarin derivatives in terms of cytotoxicity towards human and murine carcinoma cell lines (HT29, HepG2, A549, MCF7, OVCAR and CT26). Amongst those compounds, (E)-7-methoxy-4-(3-oxo-3- phenylprop-1-enyl)-2H-chromen-2-one and (E)-7-hydroxy-4-(3-(4-hydroxyphenyl)-3-oxoprop-1-enyl)-2H-chromen-2-one displayed the most potent cytotoxic effect on colon cancer cells, CT26, (IC50=4.9µM) linked to their pro-oxidant properties. Those compounds triggered the in vitro production of reactive oxygen species by tumor cells, leading to their death through a necrotic process. In vivo, molecules also slowed down tumor growth by 65.7% and 35.4%, respectively, without inducing significant side effects.

Introduction: The aim of this study was to test the naturally occurring organosulfur compound dipropyltetrasulfide (DPTTS), found in plants, which has antibiotic and anticancer properties, as a treatment for HOCl-induced systemic sclerosis in the mouse., Methods: The prooxidative, antiproliferative, and cytotoxic effects of DPTTS were evaluated ex vivo on fibroblasts from normal and HOCl mice. In vivo, the antifibrotic and immunomodulating properties of DPTTS were evaluated in the skin and lungs of HOCl mice., Results: H2O2 production was higher in fibroblasts derived from HOCl mice than in normal fibroblasts (P < 0.05). DPTTS did not increase H2O2 production in normal fibroblasts, but DPTTS dose-dependently increased H2O2 production in HOCl fibroblasts (P < 0.001 with 40 μM DPTTS). Because H2O2 reached a lethal threshold in cells from HOCl mice, the antiproliferative, cytotoxic, and proapoptotic effects of DPTTS were significantly higher in HOCl fibroblasts than for normal fibroblasts. In vivo, DPTTS decreased dermal thickness (P < 0.001), collagen content in skin (P < 0.01) and lungs (P < 0.05), αSMA (P < 0.01) and pSMAD2/3 (P < 0.01) expression in skin, formation of advanced oxidation protein products and anti-DNA topoisomerase-1 antibodies in serum (P < 0.05) versus untreated HOCl mice. Moreover, in HOCl mice, DPTTS reduced splenic B-cell counts (P < 0.01), the proliferative rates of B-splenocytes stimulated by lipopolysaccharide (P < 0.05), and T-splenocytes stimulated by anti-CD3/CD28 mAb (P < 0.001). Ex vivo, it also reduced the production of IL-4 and IL-13 by activated T cells (P < 0.05 in both cases)., Conclusions: The natural organosulfur compound DPTTS prevents skin and lung fibrosis in the mouse through the selective killing of diseased fibroblasts and its immunomodulating properties. DPTTS may be a potential treatment for systemic sclerosis.

Many sulfur compounds are known to exhibit widespread antimicrobial activity. The latter is often the result of an intricate redox biochemistry whereby reactive sulfur species, such as organic polysulfanes, interact with pivotal cellular signaling pathways. The S8 unit in elemental sulfur resembles certain aspects of the chemistry of polysulfanes. As a consequence, water-soluble S8-sulfur nanoparticles are active against some smaller organisms, including nematodes, yet are non-toxic against human cells. In contrast, selenium and tellurium nanoparticles are less active. Together, the ease of production of the sulfur nanoparticles, their chemical stability in aqueous dispersion, amenable physical properties and selective toxicity, turn sulfur nanoparticles into promising antimicrobial prototypes for medical as well as agricultural applications.

Various secondary metabolites from plants, bacteria and fungi are redox active and able to modulate the intracellular redox equilibrium in living cells. Many of these compounds behave as antioxidants, yet some of them also cause oxidative modifications, which may ultimately result in cell death. Natural isothiocyanates and xanthohumol, for instance, appear to act specifically in and against cells with a disturbed redox balance, such as certain cancer cells. Similarly, polysulfane and pyocyanin derivatives employ the glutathione antioxidant defense system of cells to generate a lethal cocktail of reactive oxygen species. Together, these redox-modulating metabolites provide promising new leads to target selectively certain cancer cells. They may also be useful in the treatment of autoinflammatory diseases., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Tellurium has long appeared as a nearly 'forgotten' element in Biology, with most studies focusing on tellurite, tellurate and a handful of organic tellurides. During the last decade, several discoveries have fuelled a renewed interest in this element. Bioincorporation of telluromethionine provides a new approach to add heavy atoms to selected sites in proteins. Cadmium telluride (CdTe) nanoparticles are fluorescent and may be used as quantum dots in imaging and diagnosis. The antibiotic properties of tellurite, long known yet almost forgotten, have attracted renewed interest, especially since the biochemical mechanisms of tellurium cytotoxicity are beginning to emerge. The close chemical relationship between tellurium and sulfur also transcends into in vitro and in vivo situations and provides new impetus for the development of enzyme inhibitors and redox modulators, some of which may be of interest in the field of antibiotics and anticancer drug design.

Various human diseases, including different types of cancer, are associated with a disturbed intracellular redox balance and oxidative stress (OS). The past decade has witnessed the emergence of redox-modulating compounds able to utilize such pre-existing disturbances in the redox state of sick cells for therapeutic advantage. Selenium- and tellurium-based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species that push these cells over a critical redox threshold and ultimately kill them through apoptosis. This kind of toxicity is highly selective: normal, healthy cells remain largely unaffected, since changes to their naturally low levels of oxidizing species produce little effect. To further improve selectivity, multifunctional sensor/effector agents are now required that recognize the biochemical signature of OS in target cells. The synthesis of such compounds provides interesting challenges for chemistry in the future.