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Eggenstein-Leopoldshafen, Germany

Feng W.,Karlsruhe Institute of Technology | Li L.,Karlsruhe Institute of Technology | Yang C.,Institute of Functional Interfaces IFG | Welle A.,Karlsruhe Institute of Technology | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2015

A UV-induced 1,3-dipolar nucleophilic addition of tetrazoles to thiols is described. Under UV irradiation the reaction proceeds rapidly at room temperature, with high yields, without a catalyst, and in both polar protic and aprotic solvents, including water. This UV-induced tetrazole-thiol reaction was successfully applied for the synthesis of small molecules, protein modification, and rapid and facile polymer-polymer conjugation. The reaction has also been demonstrated for the formation of micropatterns by site-selective surface functionalization. Superhydrophobic-hydrophilic micropatterns were successfully created by sequential modifications of a tetrazole-modified porous polymer surface with hydrophobic and hydrophilic thiols. A biotin-functionalized surface could be fabricated in aqueous solutions under long-wavelength UV irradiation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Schafer A.I.,Institute of Functional Interfaces IFG | Schafer A.I.,Nelson Mandela African Institute of Science and Technology NM AIST | Schafer A.I.,University of Edinburgh | Hughes G.,University of Edinburgh | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

Lack of access to safe drinking water remains a present concern in many developing countries, particularly in rural locations. Membrane water treatment technologies have the potential to remove microbiological and chemical contaminants reliably and simultaneously from a wide range of water sources. When powered by renewable energy, these systems are autonomous and have the ability to 'leapfrog' over installation of traditional infrastructure for electricity and water supply to reach remote communities. In this paper, current estimated costs for water, membrane plants and infrastructure are compared to indicate the window of opportunity for these exciting renewable energy powered membrane (RE-membrane) technologies. General estimated costs for decentralized membrane systems are within the range of some untreated water costs in developing countries. Specific system costs, however, are very process and location dependent. The appropriateness of a successful approach thus depends partially on careful examination of these parameters. In view of the comparisons made here, the biggest hurdle to adoption of the RE-membrane technology in a remote location may not be cost, but rather sustainability issues such as the lack of skilled personnel for operation and maintenance, service networks, availability of spare parts, socio-economic integration and adaptive capacity of communities to transfer and develop technology appropriate to local needs and circumstances. © 2014 Elsevier Ltd. Source

Burck J.,Institute of Biological Interfaces IBG2 | Heissler S.,Institute of Functional Interfaces IFG | Geckle U.,Institute of Applied Materials | Ardakani M.F.,Karlsruhe Institute of Technology | And 4 more authors.
Langmuir | Year: 2013

Electrospinning is a promising method to mimic the native structure of the extracellular matrix. Collagen is the material of choice, since it is a natural fibrous structural protein. It is an open question how much the spinning process preserves or alters the native structure of collagen. There are conflicting results in the literature, mainly due to the different solvent systems in use and due to the fact that gelatin is employed as a reference state for the completely unfolded state of collagen in calculations. Here we used circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) to investigate the structure of regenerated collagen samples and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to illuminate the electrospun nanofibers. Collagen is mostly composed of folded and unfolded structures with different ratios, depending on the applied temperature. Therefore, CD spectra were acquired as a temperature series during thermal denaturation of native calf skin collagen type I and used as a reference basis to extract the degree of collagen folding in the regenerated electrospun samples. We discussed three different approaches to determine the folded fraction of collagen, based on CD spectra of collagen from 185 to 260 nm, since it would not be sufficient to obtain simply the fraction of folded structure θ from the ellipticity at a single wavelength of 221.5 nm. We demonstrated that collagen almost completely unfolded in fluorinated solvents and partially preserved its folded structure θ in HAc/EtOH. However, during the spinning process it refolded and the PP-II fraction increased. Nevertheless, it did not exceed 42% as deduced from the different secondary structure evaluation methods, discussed here. PP-II fractions in electrospun collagen nanofibers were almost same, being independent from the initial solvent systems which were used to solubilize the collagen for electrospinning process. © 2012 American Chemical Society. Source

Tsotsalas M.,Institute of Functional Interfaces IFG | Liu J.,Institute of Functional Interfaces IFG | Tettmann B.,Institute of Functional Interfaces IFG | Grosjean S.,Institute for Biological Interfaces IBG | And 11 more authors.
Journal of the American Chemical Society | Year: 2014

We report the fabrication of 3D, highly porous, covalently bound polymer films of homogeneous thickness. These surface-bound gels combine the advantages of metal-organic framework (MOF) materials, namely, the enormous flexibility and the large size of the maximum pore structures and, in particular, the possibility to grow them epitaxially on modified substrates, with those of covalently connected gel materials, namely, the absence of metal ions in the deposited material, a robust framework consisting of covalent bonds, and, most importantly, pronounced stability under biological conditions. The conversion of a SURMOF (surface-mounted MOF) yields a surface-grafted gel. These SURGELs can be loaded with bioactive compounds and applied as bioactive coatings and provide a drug-release platform in in vitro cell culture studies. © 2013 American Chemical Society. Source

Borowicki A.,Friedrich - Schiller University of Jena | Michelmann A.,Friedrich - Schiller University of Jena | Stein K.,Friedrich - Schiller University of Jena | Scharlau D.,Friedrich - Schiller University of Jena | And 3 more authors.
Nutrition and Cancer | Year: 2011

Fermentation of dietary fiber by the microflora enhances the levels of effective metabolites, which are potentially protective against colon cancer. The specific addition of probiotics may enhance the efficiency of fermentation of wheat aleurone, a source of dietary fiber. We investigated the effects of aleurone, fermented with fecal slurries with the addition of the probiotics LGG and Bb12 (aleurone+), on cell growth, apoptosis, and differentiation, as well as expression of genes related to growth and apoptosis using two different human colon cell lines (HT29: adenocarcinoma cells; LT97: adenoma cells). The efficiency of fermentation of aleurone was only slightly enhanced by the addition of LGG/Bb12, resulting in an increased concentration of butyrate. In LT97 cells, the growth inhibition of aleurone+ was stronger than in HT29 cells. In HT29 cells, a cell cycle arrest in G0/G1 and the alkaline phosphatase activity, a marker of differentiation, were enhanced by the fs aleurone+. Treatment with all fermentation supernatants resulted in a significant increase in apoptosis and an upregulation of genes involved in cell growth and apoptosis (p21 and WNT2B). In conclusion, fs aleurone+ modulated markers of cancer prevention, namely inhibition of cell growth and promotion of apoptosis as well as differentiation. Copyright © 2011, Taylor & Francis Group, LLC. Source

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