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- ItemGas-Phase Fluorination on PLA Improves Cell Adhesion and Spreading(Washington, DC : Soc., 2020) Schroepfer, Michaela; Junghans, Frauke; Voigt, Diana; Meyer, Michael; Breier, Anette; Schulze-Tanzil, Gundula; Prade, InaFor the regeneration or creation of functional tissues, biodegradable biomaterials including polylactic acid (PLA) are widely preferred. Modifications of the material surface are quite common to improve cell-material interactions and thereby support the biological outcome. Typical approaches include a wet chemical treatment with mostly hazardous substances or a functionalization with plasma. In the present study, gas-phase fluorination was applied to functionalize the PLA surfaces in a simple and one-step process. The biological response including biocompatibility, cell adhesion, cell spreading, and proliferation was analyzed in cell culture experiments with fibroblasts L929 and correlated with changes in the surface properties. Surface characterization methods including surface energy and isoelectric point measurements, X-ray photoelectron spectroscopy, and atomic force microscopy were applied to identify the effects of fluorination on PLA. Gas-phase fluorination causes the formation of C-F bonds in the PLA backbone, which induce a shift to a more hydrophilic and polar surface. The slightly negatively charged surface dramatically improves cell adhesion and spreading of cells on the PLA even with low fluorine content. The results indicate that this improved biological response is protein-but not integrin-dependent. Gas-phase fluorination is therefore an efficient technique to improve cellular response to biomaterial surfaces without losing cytocompatibility. Copyright © 2020 American Chemical Society.
- ItemRemarkable Mechanochromism in Blends of a π-Conjugated Polymer P3TEOT: The Role of Conformational Transitions and Aggregation(Weinheim : Wiley-VCH, 2020) Zessin, Johanna; Schnepf, Max; Oertel, Ulrich; Beryozkina, Tetyana; König, Tobias A.F.; Fery, Andreas; Mertig, Michael; Kiriy, AntonA novel mechanism for well-pronounced mechanochromism in blends of a π-conjugated polymer based on reversible conformational transitions of a chromophore rather than caused by its aggregation state, is exemplified. Particularly, a strong stretching-induced bathochromic shift of the light absorption, or hypsochromic shift of the emission, is found in blends of the water-soluble poly(3-tri(ethylene glycol)) (P3TEOT) embedded into the matrix of thermoplastic polyvinyl alcohol. This counterintuitive phenomenon is explained in terms of the concentration dependency of the P3TEOT's aggregation state, which in turn results in different molecular conformations and optical properties. A molecular flexibility, provided by low glass transition temperature of P3TEOT, and the fact that P3TEOT adopts an intermediate, moderately planar conformation in the solid state, are responsible for the unusual complex mechanochromic behavior. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemEMT-Induced Cell-Mechanical Changes Enhance Mitotic Rounding Strength(Weinheim : Wiley-VCH, 2020) Hosseini, Kamran; Taubenberger, Anna; Werner, Carsten; Fischer-Friedrich, ElisabethTo undergo mitosis successfully, most animal cells need to acquire a round shape to provide space for the mitotic spindle. This mitotic rounding relies on mechanical deformation of surrounding tissue and is driven by forces emanating from actomyosin contractility. Cancer cells are able to maintain successful mitosis in mechanically challenging environments such as the increasingly crowded environment of a growing tumor, thus, suggesting an enhanced ability of mitotic rounding in cancer. Here, it is shown that the epithelial–mesenchymal transition (EMT), a hallmark of cancer progression and metastasis, gives rise to cell-mechanical changes in breast epithelial cells. These changes are opposite in interphase and mitosis and correspond to an enhanced mitotic rounding strength. Furthermore, it is shown that cell-mechanical changes correlate with a strong EMT-induced change in the activity of Rho GTPases RhoA and Rac1. Accordingly, it is found that Rac1 inhibition rescues the EMT-induced cortex-mechanical phenotype. The findings hint at a new role of EMT in successful mitotic rounding and division in mechanically confined environments such as a growing tumor.
- ItemBioinspired Polydopamine Coating as an Adhesion Enhancer Between Paraffin Microcapsules and an Epoxy Matrix(Washington, DC : ACS Publications, 2020) Fredi, Giulia; Simon, Frank; Sychev, Dmitrii; Melnyk, Inga; Janke, Andreas; Scheffler, Christina; Zimmerer, CordeliaMicroencapsulated phase change materials (PCMs) are attracting increasing attention as functional fillers in polymer matrices, to produce smart thermoregulating composites for applications in thermal energy storage (TES) and thermal management. In a polymer composite, the filler–matrix interfacial adhesion plays a fundamental role in the thermomechanical properties. Hence, this work aims to modify the surface of commercial PCM microcapsules through the formation of a layer of polydopamine (PDA), a bioinspired polymer that is emerging as a powerful tool to functionalize chemically inert surfaces due to its versatility and great adhesive potential in many different materials. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) evidenced that after PDA coating, the surface roughness increased from 9 to 86 nm, which is beneficial, as it allows a further increase in the interfacial interaction by mechanical interlocking. Spectroscopic techniques allowed investigating the surface chemistry and identifying reactive functional groups of the PDA layer and highlighted that, unlike the uncoated microcapsules, the PDA layer is able to react with oxirane groups, thereby forming a covalent bond with the epoxy matrix. Hot-stage optical microscopy and differential scanning calorimetry (DSC) highlighted that the PDA modification does not hinder the melting/crystallization process of the paraffinic core. Finally, SEM micrographs of the cryofracture surface of epoxy composites containing neat or PDA-modified microcapsules clearly evidenced improved adhesion between the capsule shell and the epoxy matrix. These results showed that PDA is a suitable coating material with considerable potential for increasing the interfacial adhesion between an epoxy matrix and polymer microcapsules with low surface reactivity. This is remarkably important not only for this specific application but also for other classes of composite materials. Future studies will investigate how the deposition parameters affect the morphology, roughness, and thickness of the PDA layer and how the layer properties influence the capsule–matrix adhesion.
- ItemDNAzymes as Catalysts for l-Tyrosine and Amyloid β Oxidation(Washington, DC : ACS Publications, 2020) Köhler, Tony; Patsis, Panagiotis A.; Hahn, Dominik; Ruland, André; Naas, Carolin; Müller, Martin; Thiele, JulianSingle-stranded deoxyribonucleic acids have an enormous potential for catalysis by applying tailored sequences of nucleotides for individual reaction conditions and substrates. If such a sequence is guanine-rich, it may arrange into a three-dimensional structure called G-quadruplex and give rise to a catalytically active DNA molecule, a DNAzyme, upon addition of hemin. Here, we present a DNAzyme-mediated reaction, which is the oxidation of l-tyrosine toward dityrosine by hydrogen peroxide. With an optimal stoichiometry between DNA and hemin of 1:10, we report an activity of 101.2 ± 3.5 μUnits (μU) of the artificial DNAzyme Dz-00 compared to 33.0 ± 1.8 μU of free hemin. Exemplarily, DNAzymes may take part in neurodegeneration caused by amyloid beta (Aβ) aggregation due to l-tyrosine oxidation. We show that the natural, human genome-derived DNAzyme In1-sp is able to oxidize Aβ peptides with a 4.6% higher yield and a 33.3% higher velocity of the reaction compared to free hemin. As the artificial DNAzyme Dz-00 is even able to catalyze Aβ peptide oxidation with a 64.2% higher yield and 337.1% higher velocity, an in-depth screening of human genome-derived DNAzymes may identify further candidates with similarly high catalytic activity in Aβ peptide oxidation.
- Item3D Quantification of Vascular-Like Structures in z Stack Confocal Images(Amsterdam : Elsevier, 2020) Bonda, Ulrich; Jaeschke, Anna; Lighterness, Anthony; Baldwin, Jeremy; Werner, Carsten; De-Juan-Pardo, Elena M.; Bray, Laura J.Optical slice microscopy is commonly used to characterize the morphometric features of 3D cellular cultures, such as in vitro vascularization. However, the quantitative analysis of those structures is often performed on a single 2D maximum intensity projection image, limiting the accuracy of data obtained from 3D cultures. Here, we present a protocol for the quantitative analysis of z stack images, utilizing Fiji, Amira, and WinFiber3D. This protocol facilitates the in-depth examination of vascular-like structures within 3D cell culture models.
- ItemLightweight polymer-carbon composite current collector for lithium-ion batteries(Basel : MDPI, 2020) Fritsch, Marco; Coeler, Matthias; Kunz, Karina; Krause, Beate; Marcinkowski, Peter; Pötschke, Petra; Wolter, Mareike; Michaelis, AlexanderA hermetic dense polymer-carbon composite-based current collector foil (PCCF) for lithium-ion battery applications was developed and evaluated in comparison to state-of-the-art aluminum (Al) foil collector. Water-processed LiNi0.5Mn1.5O4 (LMNO) cathode and Li4Ti5O12 (LTO) anode coatings with the integration of a thin carbon primer at the interface to the collector were prepared. Despite the fact that the laboratory manufactured PCCF shows a much higher film thickness of 55 µm compared to Al foil of 19 µm, the electrode resistance was measured to be by a factor of 5 lower compared to the Al collector, which was attributed to the low contact resistance between PCCF, carbon primer and electrode microstructure. The PCCF-C-primer collector shows a sufficient voltage stability up to 5 V vs. Li/Li+ and a negligible Li-intercalation loss into the carbon primer. Electrochemical cell tests demonstrate the applicability of the developed PCCF for LMNO and LTO electrodes, with no disadvantage compared to state-of-the-art Al collector. Due to a 50% lower material density, the lightweight and hermetic dense PCCF polymer collector offers the possibility to significantly decrease the mass loading of the collector in battery cells, which can be of special interest for bipolar battery architectures. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Item4D Biofabrication of fibrous artificial nerve graft for neuron regeneration(Bristol : IOP Publ., 2020) Apsite, Indra; Constante, Gissela; Dulle, Martin; Vogt, Lena; Caspari, Anja; Boccaccini, Aldo R.; Synytska, Alla; Salehi, Sahar; Ionov, LeonidIn this paper, we describe the application of the 4D biofabrication approach for the fabrication of artificial nerve graft. Bilayer scaffolds consisting of uniaxially aligned polycaprolactone-poly(glycerol sebacate) (PCL-PGS) and randomly aligned methacrylated hyaluronic acid (HA-MA) fibers were fabricated using electrospinning and further used for the culture of PC-12 neuron cells. Tubular structures form instantly after immersion of fibrous bilayer in an aqueous buffer and the diameter of obtained tubes can be controlled by changing bilayer parameters such as the thickness of each layer, overall bilayer thickness, and medium counterion concentration. Designed scaffolds showed a self-folded scroll-like structure with high stability after four weeks of real-time degradation. The significance of this research is in the fabrication of tuneable tubular nerve guide conduits that can simplify the current existing clinical treatment of neural injuries. © 2020 The Author(s). Published by IOP Publishing Ltd.
- ItemTuning of Smart Multifunctional Polymer Coatings Made by Zwitterionic Phosphorylcholines(Weinheim : Wiley-VCH, 2020) Münch, Alexander S.; Adam, Stefan; Fritzsche, Tina; Uhlmann, PetraIn the last years, the generation of multifunctional coatings has been moved into the focus of interface modifications to expand the spectrum of material applications and to introduce new smart properties. Herein a promising multifunctional and universally usable coating with simultaneous antifouling, easy-to-clean, and anti-fog functionality is presented based on smart polymer films consisting of copolymers with 2-methacryloyloxyethyl phosphorylcholine (MPC), realizing the function of the film and photoreactive 4-benzophenyl methacrylate (BPO), which is responsible for stability and crosslinking. The easy-to-clean effect is demonstrated qualitatively and quantitatively by oil droplet detachment experiments. The antifouling behavior against different germs is investigated by cell adhesion experiments. Furthermore the anti-fog performance is shown by breathing on the surfaces. To study the influence of the different amounts of copolymerized BPO, the grafted films are characterized by atomic force microscopy (AFM), infrared spectroscopy (ATR-FTIR), as well as contact angle measurements. In situ spectroscopic ellipsometry is performed to investigate the swelling behavior of the thin films as a function of the time of UV-irradiation. It is found that a degree of swelling of 15 and a water contact angle of less than 12° are the key parameters necessary for the generation of multifunctional coatings. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemCell-Instructive Multiphasic Gel-in-Gel Materials(Weinheim : Wiley-VCH, 2020) Kühn, Sebastian; Sievers, Jana; Stoppa, Aukha; Träber, Nicole; Zimmermann, Ralf; Welzel, Petra B.; Werner, CarstenDeveloping tissue is typically soft, highly hydrated, dynamic, and increasingly heterogeneous matter. Recapitulating such characteristics in engineered cell-instructive materials holds the promise of maximizing the options to direct tissue formation. Accordingly, progress in the design of multiphasic hydrogel materials is expected to expand the therapeutic capabilities of tissue engineering approaches and the relevance of human 3D in vitro tissue and disease models. Recently pioneered methodologies allow for the creation of multiphasic hydrogel systems suitable to template and guide the dynamic formation of tissue- and organ-specific structures across scales, in vitro and in vivo. The related approaches include the assembly of distinct gel phases, the embedding of gels in other gel materials and the patterning of preformed gel materials. Herein, the capabilities and limitations of the respective methods are summarized and discussed and their potential is highlighted with some selected examples of the recent literature. As the modularity of the related methodologies facilitates combinatorial and individualized solutions, it is envisioned that multiphasic gel-in-gel materials will become a versatile morphogenetic toolbox expanding the scope and the power of bioengineering technologies. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim