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    Highly Conductive, Stretchable, and Cell-Adhesive Hydrogel by Nanoclay Doping
    (Weinheim : Wiley-VCH, 2019) Tondera, Christoph; Akbar, Teuku Fawzul; Thomas, Alvin Kuriakose; Lin, Weilin; Werner, Carsten; Busskamp, Volker; Zhang, Yixin; Minev, Ivan R.
    Electrically conductive materials that mimic physical and biological properties of tissues are urgently required for seamless brain-machine interfaces. Here, a multinetwork hydrogel combining electrical conductivity of 26 S m-1 , stretchability of 800%, and tissue-like elastic modulus of 15 kPa with mimicry of the extracellular matrix is reported. Engineering this unique set of properties is enabled by a novel in-scaffold polymerization approach. Colloidal hydrogels of the nanoclay Laponite are employed as supports for the assembly of secondary polymer networks. Laponite dramatically increases the conductivity of in-scaffold polymerized poly(ethylene-3,4-diethoxy thiophene) in the absence of other dopants, while preserving excellent stretchability. The scaffold is coated with a layer containing adhesive peptide and polysaccharide dextran sulfate supporting the attachment, proliferation, and neuronal differentiation of human induced pluripotent stem cells directly on the surface of conductive hydrogels. Due to its compatibility with simple extrusion printing, this material promises to enable tissue-mimetic neurostimulating electrodes.
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    Screening Arrays of Laminin Peptides on Modified Cellulose for Promotion of Adhesion of Primary Endothelial and Neural Precursor Cells
    (Weinheim : Wiley-VCH, 2021) Wetzel, Richard; Hauser, Sandra; Lin, Weilin; Berg, Peggy; Werner, Carsten; Pietzsch, Jens; Kempermann, Gerd; Zhang, Yixin
    Neural precursor cells (NPC) are primary cells intensively used in the context of research on adult neurogenesis and modeling of neuronal development in health and diseased states. Substrates that can facilitate NPC adhesion will be very useful for culturing these cells. Due to the presence of laminin in basal lamina as well as their involvement in differentiation, migration, and adhesion of many types of cells, surfaces modified with laminin-derived peptides are focused upon and compared with the widely used fibronectin-derived Arg-Gly-Asp (RGD) peptides. An array of 46 peptides is synthesized on cellulose paper (SPOT) to identify laminin-derived peptides that promote short-term adhesion of murine NPC and human primary endothelial cells. Various previously reported peptide sequences are re-evaluated in this work. Initial adhesion experiments show NPC preferred several laminin-derived peptides by up to 5-time higher cell numbers, compared to the well-known promiscuous integrin binding RGD peptide. Importantly, screening of cell adhesion has revealed a synergetic effect of filamentous matrix, peptide sequence, surface property, ligand density, and the dynamic process of NPC adhesion. © The Authors. Advanced Biology published by Wiley-VCH GmbH