Conducting polyaniline–montmorillonite composites

Polyaniline (PANI)–montmorillonite (MMT) composites were prepared in two ways: (a) by the polymerization of aniline hydrochloride with ammonium peroxydisulfate (APS) in aqueous suspensions of MMT, (b) by the intercalation of aniline hydrochloride into MMT in aqueous suspension followed by the oxidation with APS, i.e. by the surface and intercalative polymerizations of aniline. The products were analyzed by SEM, XRD, TGA, FTIR and Raman spectroscopies. The formation of red coloration after interaction of MMT with aniline is discussed. The conductivity of PANI–MMT composites increased to units S cm^?1 as the content of PANI reached 50–60 wt.%. The intercalation of aniline into MMT before the polymerization had no marked effect on the conductivity of resulting composites, which was determined mainly by the PANI present at the MMT particles surfaces.     

Polyaniline–silver composites prepared by the oxidation of aniline with silver nitrate in acetic acid solutions

The reaction between two non‐conducting chemicals, aniline and silver nitrate, yields a composite of two conducting components, polyaniline and metallic silver. Such conducting polymer composites combine the electrical properties of metals and the materials properties of polymers. In the present study, aniline was oxidized with silver nitrate in solutions of acetic acid; in this context, aniline oligomers are often a major component of the oxidation products. An insoluble precipitate of silver acetate is also present in the samples. The optimization of reaction conditions with respect to aniline and acetic acid concentrations leads to a conductivity of the composite as high as 8000 S cm^?1 at ca 70 wt% (ca 21 vol%) of silver. A sufficient concentration of acetic acid, as well as a time extending to several weeks, has to be provided for the successful polymerization of aniline. Polyaniline is present as nanotubes or nanobrushes composed of thin nanowires. The average size of the silver nanoparticles is 30–50 nm; silver nanowires are also observed. Copyright © 2009 Society of Chemical Industry     

Development of an Efficient Dual‐Action GST‐Inhibiting Anticancer Platinum(IV) Prodrug

The cytotoxicity of cisplatin (cDDP) is enhanced when co‐administered with ethacrynic acid (EA), a glutathione S‐transferase (GST) inhibitor. A Pt^IV–EA conjugate containing a cDDP core and two axial ethacrynate ligands (compound 1 ) was shown to be an excellent inhibitor of GST, but did not readily release a Pt^II species to exert a synergistic cytotoxic effect. In this study, a redesigned Pt^IV construct composed of a cDDP core with one axial ethacrynate ligand and one axial hydroxido ligand (compound 2 ) was prepared and shown to overcome the limitations of compound 1 . The EA ligand in 2 is readily released in vitro together with a cytotoxic Pt^II species derived from cisplatin, working together to inhibit cell proliferation in cDDP‐resistant human ovarian cancer cells. The in vitro activity translates well in vivo with 2 , showing effective (～80 %) inhibition of tumor growth in a human ovarian carcinoma A2780 tumor model, while showing considerably lower toxicity than cisplatin, thus validating the new design strategy.     

Olefin Metathesis of Vinylgermanium Derivatives as Method for the Synthesis of Functionalized Cubic and Double‐Decker Germasilsesquioxanes

For the first time, olefin cross metathesis has been developed for vinylgermanium compounds. This paper also marks the first case of transition metal‐catalyzed functionalization of heterosilsesquioxanes, which in our case are cubic vinylgermasilsesquioxanes and newly synthesized di(vinylgermyl)substituted double‐decker silsesquioxane. These processes lead to a series of new molecular, unsaturated mono‐ and divinyl‐substituted germasilsesquioxanes, which can be potentially applied as precursors for optoelectronics and for the synthesis of new advanced materials. Additionally, preliminary tests of metathetic copolymerization of divinylsubstituted double‐decker digermasilsesquioxanes (DDSQ‐2ViGe) with selected diolefins proved to be very promising and resulted in the synthesis of novel stereoregular trans‐germasilsesquioxyl‐vinylene‐phenylene macromolecular derivatives. All newly obtained compounds were isolated and characterized by mass and spectroscopic methods.

     

The Importance of CXCL1 in the Physiological State and in Noncancer Diseases of the Oral Cavity and Abdominal Organs

CXCL1 is a CXC chemokine, CXCR2 ligand and chemotactic factor for neutrophils. In this paper, we present a review of the role of the chemokine CXCL1 in physiology and in selected major non-cancer diseases of the oral cavity and abdominal organs (gingiva, salivary glands, stomach, liver, pancreas, intestines, and kidneys). We focus on the importance of CXCL1 on implantation and placentation as well as on human pluripotent stem cells. We also show the significance of CXCL1 in selected diseases of the abdominal organs, including the gastrointestinal tract and oral cavity (periodontal diseases, periodontitis, Sjögren syndrome, Helicobacter pylori infection, diabetes, liver cirrhosis, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), HBV and HCV infection, liver ischemia and reperfusion injury, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), obesity and overweight, kidney transplantation and ischemic-reperfusion injury, endometriosis and adenomyosis).     

Towards Light-Activated Ruthenium–Arene (RAPTA-Type) Prodrug Candidates

Cancer is currently one of the deadliest diseases worldwide. Based on the high incidence of this disease, the side effects associated with current chemotherapies and the appearance of drug resistance, considerable efforts have been directed towards the development of new anticancer drugs with new modes of action. Metal-based compounds are particularly attractive candidates due to their metabolic mechanisms, which differ substantially from those of organic drugs. Of special interest in this context are organometallic ruthenium(II) complexes of the type [Ru(η⁶-arene)(pta)Cl₂] (arene: p-cymene, toluene, benzene, etc.; pta: 1,3,5-triaza-7-phosphaadamantane), which are abbreviated to RAPTA. Complementary to chemotherapy, photoactivated chemotherapy is a technique that has received increasing attention towards the development of treatment for numerous kinds of cancer. With this in mind, a photoactive RAPTA-type complex bearing azide ligands has been designed. The diazide complex, [Ru(η⁶-p-cymene)pta-(N₃)₂], is inert in water, but slowly releases the azide ligand upon exposure to light. Consequently, the in vitro cytotoxicity of the complex in the dark and upon light exposure at λ=450 nm in human cervical carcinoma (HeLa) and noncancerous retinal pigment epithelium (RPE-1) cells was investigated. Although the cytotoxicity of the complex was found to be modest in the dark, an increase in toxicity upon light exposure was observed.     

Gastrointestinal Dopamine in Inflammatory Bowel Diseases: A Systematic Review

Background: an increased prevalence of gastro-duodenal ulceration was described almost sixty years ago as prodromal to idiopathic Parkinson’s disease, while duodenal ulcers have been rarely diagnosed in patients with schizophrenia. The cytoprotective role of dopamine in animal models of gastrointestinal ulcerations has also been described. Interestingly, Parkinson’s disease (PD) might share common pathophysiological links with inflammatory bowel disease (IBD) as epidemiological and genetic links already suggest. Thus, the aim of our study was to review the existing literature on the role of the gastrointestinal dopaminergic system in IBD pathogenesis and progression. Methods: a systematic search was conducted according to the PRISMA methodology. Results: twenty-four studies satisfied the predetermined criteria and were included in our qualitative analysis. Due to different observations (cross-sectional studies) as well as experimental setups and applied methodologies (in vivo and in vitro studies) a meta-analysis could not be performed. No ongoing clinical trials with dopaminergic compounds in IBD patients were found. Conclusions: the impairment of the dopaminergic system seems to be a significant, yet underestimated, feature of IBD, and more in-depth observational studies are needed to further support the existing preclinical data.     

Rotating Magnetic Field Increases β-Lactam Antibiotic Susceptibility of Methicillin-Resistant Staphylococcus aureus Strains

Methicillin-resistant strains of Staphylococcus aureus (MRSA) have developed resistance to most β-lactam antibiotics and have become a global health issue. In this work, we analyzed the impact of a rotating magnetic field (RMF) of well-defined and strictly controlled characteristics coupled with β-lactam antibiotics against a total of 28 methicillin-resistant and sensitive S. aureus strains. The results indicate that the application of RMF combined with β-lactam antibiotics correlated with favorable changes in growth inhibition zones or in minimal inhibitory concentrations of the antibiotics compared to controls unexposed to RMF. Fluorescence microscopy indicated a drop in the relative number of cells with intact cell walls after exposure to RMF. These findings were additionally supported by the use of SEM and TEM microscopy, which revealed morphological alterations of RMF-exposed cells manifested by change of shape, drop in cell wall density and cytoplasm condensation. The obtained results indicate that the originally limited impact of β-lactam antibiotics in MRSA is boosted by the disturbances caused by RMF in the bacterial cell walls. Taking into account the high clinical need for new therapeutic options, effective against MRSA, the data presented in this study have high developmental potential and could serve as a basis for new treatment options for MRSA infections.