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End date: 2024 × Start date: 2020 × End date: 2024 × Start date: 2020 × DDC: 600 × Publisher: Weinheim : Wiley-VCH × WGL Institute: DWI ×

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    Wet-Spinning of Biocompatible Core–Shell Polyelectrolyte Complex Fibers for Tissue Engineering
    (Weinheim : Wiley-VCH, 2020) Cui, Qing; Bell, Daniel Josef; Rauer, Sebastian Bernhard; Wessling, Matthias
    Polyelectrolyte complex fibers (PEC fibers) have great potential with regard to biomedical applications as they can be fabricated from biocompatible and water-soluble polyelectrolytes under mild process conditions. The present publication describes a novel method for the continuous fabrication of PEC fibers in a water-based wet-spinning process by interfacial complexation within a core–shell spinneret. This process combines the robustness and flexibility of nonsolvent-induced phase separation (NIPS) spinning processes conventionally used in the membrane industry with the complexation between oppositely charged polyelectrolytes. The produced fibers demonstrate a core–shell structure with a low-density core and a highly porous polyelectrolyte complex shell of ≈800 μm diameter. In the case of chitosan and polystyrene sulfonate (PSS), mechanical fiber properties could be enhanced by doping the PSS with poly(ethylene oxide) (PEO). The resulting CHI/PSS-PEO fibers present a Young modulus of 3.78 GPa and a tensile strength of 165 MPa, which is an excellent combination of elongation at break and break stress compared to literature. The suitability of the CHI/PSS-PEO fibers as a scaffold for cell culture applications is verified by a four-day cultivation of human HeLa cells on PEO-reinforced fibers with a subsequent analysis of cell viability by fluorescence-based live/dead assay. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Oligothiophene-Based Phosphonates for Surface Modification of Ultraflat Transparent Conductive Oxides
    (Weinheim : Wiley-VCH, 2020) Timpel, Melanie; Nardi, Marco V.; Wegner, Berthold; Ligorio, Giovanni; Pasquali, Luca; Hildebrandt, Jana; Pätzel, Michael; Hecht, Stefan; Ohta, Hiromichi; Koch, Norbert
    The self-assembly of electroactive organic molecules on transparent conductive oxides is a versatile strategy to engineer the interfacial energy-level alignment and to enhance charge carrier injection in optoelectronic devices. Via chemical grafting of an aromatic oligothiophene molecule by changing the position of the phosphonic acid anchoring group with respect to the organic moiety (terminal and internal), the direction of the main molecular dipole is changed, i.e., from parallel to perpendicular to the substrate, to study the molecular arrangement and electronic properties at the organic–inorganic interface. It is found that the observed work function increase cannot solely be predicted based on the calculated molecular dipole moment of the oligothiophene-based phosphonates. In addition, charge transfer from the substrate to the molecule has to be taken into account. Molecular assembly and induced electronic changes are analogous for both indium-tin oxide (ITO) and zinc oxide (ZnO), demonstrating the generality of the approach and highlighting the direct correlation between molecular coverage and electronic effects. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim