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End date: 2024 × Start date: 2020 × DDC: 570 × Has files: Yes × WGL Institute: IPF ×

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Now showing 1 - 10 of 41
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    Photo-Ordering and Deformation in Azobenzene-Containing Polymer Networks under Irradiation with Elliptically Polarized Light
    (Basel : MDPI, 2023) Toshchevikov, Vladimir; Saphiannikova, Marina
    Azobenzene-containing polymers (azo-polymers) have been a subject of extensive investigations during the last two and half decades, due to their remarkable ability to undergo pronounced alignment and deformation under irradiation with light. The molecular ordering and deformation in azo-polymers of various structures under irradiation with linearly polarized light was described in a series of theoretical works, based on the effect of the reorientation of azobenzene moieties due to the anisotropic character of the photoisomerization processes. In the present study, we generalize the previous orientation approach to describe the photo-alignment and deformation of azo-polymer networks under irradiation with elliptically polarized light. We demonstrate that, in general, the light-induced ordering and deformation have a biaxial symmetry defined by the polarization ellipse. Azobenzene chromophores have a tendency to align along the direction of light propagation, the orientation in the other two directions being dependent of the aspect ratio of the polarization ellipse. This causes deformation of azo-polymer networks along the direction of light propagation, the sign of which (expansion/contraction) is defined by a chemical structure of network strands. Theoretical results are in agreement with experiments and have a practical importance to predict the photo-mechanical response of azo-polymers depending on their structure and on the polarization of light.
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    Enhanced growth of lapine anterior cruciate ligament-derived fibroblasts on scaffolds embroidered from poly(L-lactide-co-ε-caprolactone) and polylactic acid threads functionalized by fluorination and hexamethylene diisocyanate cross-linked collagen foams
    (Basel : Molecular Diversity Preservation International, 2020) Gögele, Clemens; Hahn, Judith; Elschner, Cindy; Breier, Annette; Schröpfer, Michaela; Prade, Ina; Meyer, Michael; Schulze-Tanzil, Gundula
    Reconstruction of ruptured anterior cruciate ligaments (ACLs) is limited by the availability and donor site morbidity of autografts. Hence, a tissue engineered graft could present an alternative in the future. This study was undertaken to determine the performance of lapine (L) ACL-derived fibroblasts on embroidered poly(l-lactide-co-e-caprolactone) (P(LA-CL)) and polylactic acid (PLA) scaffolds in regard to a tissue engineering approach for ACL reconstruction. Surface modifications of P(LA-CL)/PLA by gas-phase fluorination and cross-linking of a collagen foam using either ethylcarbodiimide (EDC) or hexamethylene diisocyanate (HMDI) were tested regarding their influence on cell adhesion, growth and gene expression. The experiments were performed using embroidered P(LA-CL)/PLA scaffolds that were seeded dynamically or statically with LACL-derived fibroblasts. Scaffold cytocompatibility, cell survival, numbers, metabolic activity, ultrastructure and sulfated glycosaminoglycan (sGAG) synthesis were evaluated. Quantitative real-time polymerase chain reaction (QPCR) revealed gene expression of collagen type I (COL1A1), decorin (DCN), tenascin C (TNC), Mohawk (MKX) and tenomodulin (TNMD). All tested scaffolds were highly cytocompatible. A significantly higher cellularity and larger scaffold surface areas colonized by cells were detected in HMDI cross-linked and fluorinated scaffolds compared to those cross-linked with EDC or without any functionalization. By contrast, sGAG synthesis was higher in controls. Despite the fact that the significance level was not reached, gene expressions of ligament extracellular matrix components and differentiation markers were generally higher in fluorinated scaffolds with cross-linked collagen foams. LACL-derived fibroblasts maintained their differentiated phenotype on fluorinated scaffolds supplemented with a HMDI cross-linked collagen foam, making them a promising tool for ACL tissue engineering. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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    Light-Driven Proton Transfer for Cyclic and Temporal Switching of Enzymatic Nanoreactors
    (Weinheim : Wiley-VCH, 2020) Moreno, Silvia; Sharan, Priyanka; Engelke, Johanna; Gumz, Hannes; Boye, Susanne; Oertel, Ulrich; Wang, Peng; Banerjee, Susanta; Klajn, Rafal; Voit, Brigitte; Lederer, Albena; Appelhans, Dietmar
    Temporal activation of biological processes by visible light and subsequent return to an inactive state in the absence of light is an essential characteristic of photoreceptor cells. Inspired by these phenomena, light-responsive materials are very attractive due to the high spatiotemporal control of light irradiation, with light being able to precisely orchestrate processes repeatedly over many cycles. Herein, it is reported that light-driven proton transfer triggered by a merocyanine-based photoacid can be used to modulate the permeability of pH-responsive polymersomes through cyclic, temporally controlled protonation and deprotonation of the polymersome membrane. The membranes can undergo repeated light-driven swelling-contraction cycles without losing functional effectiveness. When applied to enzyme loaded-nanoreactors, this membrane responsiveness is used for the reversible control of enzymatic reactions. This combination of the merocyanine-based photoacid and pH-switchable nanoreactors results in rapidly responding and versatile supramolecular systems successfully used to switch enzymatic reactions ON and OFF on demand.
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    A “built-up” composite film with synergistic functionalities on Mg–2Zn–1Mn bioresorbable stents improves corrosion control effects and biocompatibility
    ([Bejing] : KeAi Publishing, 2023) Dou, Zhenglong; Chen, Shuiling; Wang, Jiacheng; Xia, Li; Maitz, Manfred F.; Tu, Qiufen; Zhang, Wentai; Yang, Zhilu; Huang, Nan
    Control of premature corrosion of magnesium (Mg) alloy bioresorbable stents (BRS) is frequently achieved by the addition of rare earth elements. However, limited long-term experience with these elements causes concerns for clinical application and alternative methods of corrosion control are sought after. Herein, we report a “built-up” composite film consisting of a bottom layer of MgF2 conversion coating, a sandwich layer of a poly (1, 3-trimethylene carbonate) (PTMC) and 3-aminopropyl triethoxysilane (APTES) co-spray coating (PA) and on top a layer of poly (lactic-co-glycolic acid) (PLGA) ultrasonic spray coating to decorate the rare earth element-free Mg–2Zn–1Mn (ZM21) BRS for tailoring both corrosion resistance and biological functions. The developed “built-up” composite film shows synergistic functionalities, allowing the compression and expansion of the coated ZM21 BRS on an angioplasty balloon without cracking or peeling. Of special importance is that the synergistic corrosion control effects of the “built-up” composite film allow for maintaining the mechanical integrity of stents for up to 3 months, where complete biodegradation and no foreign matter residue were observed about half a year after implantation in rabbit iliac arteries. Moreover, the functionalized ZM21 BRS accomplished re-endothelialization within one month.
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    Photo-functionalized TiO2 nanotubes decorated with multifunctional Ag nanoparticles for enhanced vascular biocompatibility
    (Bejing : KeAi Publishing, 2021) Chen, Jiang; Dai, Sheng; Liu, Luying; Maitz, Manfred F.; Liao, Yuzhen; Cui, Jiawei; Zhao, Ansha; Yang, Ping; Huang, Nan; Wang, Yunbing
    Titanium dioxide (TiO2) has a long history of application in blood contact materials, but it often suffers from insufficient anticoagulant properties. Recently, we have revealed the photocatalytic effect of TiO2 also induces anticoagulant properties. However, for long-term vascular implant devices such as vascular stents, besides anticoagulation, also anti-inflammatory, anti-hyperplastic properties, and the ability to support endothelial repair, are desired. To meet these requirements, here, we immobilized silver nanoparticles (AgNPs) on the surface of TiO2 nanotubes (TiO2-NTs) to obtain a composite material with enhanced photo-induced anticoagulant property and improvement of the other requested properties. The photo-functionalized TiO2-NTs showed protein-fouling resistance, causing the anticoagulant property and the ability to suppress cell adhesion. The immobilized AgNPs increased the photocatalytic activity of TiO2-NTs to enhances its photo-induced anticoagulant property. The AgNP density was optimized to endow the TiO2-NTs with anti-inflammatory property, a strong inhibitory effect on smooth muscle cells (SMCs), and low toxicity to endothelial cells (ECs). The in vivo test indicated that the photofunctionalized composite material achieved outstanding biocompatibility in vasculature via the synergy of photo-functionalized TiO2-NTs and the multifunctional AgNPs, and therefore has enormous potential in the field of cardiovascular implant devices. Our research could be a useful reference for further designing of multifunctional TiO2 materials with high vascular biocompatibility.
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    Sv40 transfected human anterior cruciate ligament derived ligamentocytes—suitable as a human in vitro model for ligament reconstruction?
    (Basel : Molecular Diversity Preservation International, 2020) Schulze-Tanzil, Gundula; Arnold, Philipp; Gögele, Clemens; Hahn, Judith; Breier, Annette; Meyer, Michael; Kohl, Benjamin; Schröpfer, Michaela; Schwarz, Silke
    Cultured human primary cells have a limited lifespan undergoing dedifferentiation or senescence. Anterior cruciate ligaments (ACL) are hypocellular but tissue engineering (TE) requires high cell numbers. Simian virus (SV) 40 tumor (T) antigen expression could extend the lifespan of cells. This study aimed to identify cellular changes induced by SV40 expression in human ACL ligamentocytes by comparing them with non-transfected ligamentocytes and tissue of the same donor to assess their applicability as TE model. Human ACL ligamentocytes (40-year-old female donor after ACL rupture) were either transfected with a SV40 plasmid or remained non-transfected (control) before monitored for SV40 expression, survival, and DNA content. Protein expression of cultured ligamentocytes was compared with the donor tissue. Ligamentocyte spheroids were seeded on scaffolds embroidered either from polylactic acid (PLA) threads solely or combined PLA and poly (L-lactide-co-e-caprolactone) (P(LA-CL)) threads. These scaffolds were further functionalized with fluorination and fibrillated collagen foam. Cell distribution and survival were monitored for up to five weeks. The transfected cells expressed the SV40 antigen throughout the entire observation time, but often exhibited random and incomplete cell divisions with significantly more dying cells, significantly more DNA and more numerous nucleoli than controls. The expression profile of non-transfected and SV40-positive ligamentocytes was similar. In contrast to controls, SV40-positive cells formed larger spheroids, produced less vimentin and focal adhesions and died on the scaffolds after 21 d. Functionalized scaffolds supported human ligamentocyte growth. SV40 antigen expressing ligamentocytes share many properties with their non-transfected counterparts suggesting them as a model, however, applicability for TE is limited. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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    CuxCo1-xFe2O4 (x = 0.33, 0.67, 1) Spinel Ferrite Nanoparticles Based Thermoplastic Polyurethane Nanocomposites with Reduced Graphene Oxide for Highly Efficient Electromagnetic Interference Shielding
    (Basel : Molecular Diversity Preservation International (MDPI), 2022-2-26) Anju; Yadav, Raghvendra Singh; Pötschke, Petra; Pionteck, Jürgen; Krause, Beate; Kuřitka, Ivo; Vilčáková, Jarmila; Škoda, David; Urbánek, Pavel; Machovský, Michal; Masař, Milan; Urbánek, Michal
    CuxCo1-x Fe2O4 (x = 0.33,0.67,1)-reduced graphene oxide (rGO)-thermoplastic polyurethane (TPU) nanocomposites exhibiting highly efficient electromagnetic interference (EMI) shielding were prepared by a melt-mixing approach using a microcompounder. Spinel ferrite Cu0.33Co0.67Fe2O4 (Cu-CoF1), Cu0.67Co0.33Fe2O4 (CuCoF2) and CuFe2O4 (CuF3) nanoparticles were synthesized using the sonochemical method. The CuCoF1 and CuCoF2 exhibited typical ferromagnetic features, whereas CuF3 displayed superparamagnetic characteristics. The maximum value of EMI total shielding effectiveness (SEt) was noticed to be 42.9 dB, 46.2 dB, and 58.8 dB for CuCoF1-rGO-TPU, CuCoF2-rGO-TPU, and CuF3-rGO-TPU nanocomposites, respectively, at a thickness of 1 mm. The highly efficient EMI shielding performance was attributed to the good impedance matching, conductive, dielectric, and magnetic loss. The demonstrated nanocomposites are promising candidates for a lightweight, flexible, and highly efficient EMI shielding material.
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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
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    Understanding Beta-Lactam-Induced Lysis at the Single-Cell Level
    (Lausanne : Frontiers Media, 2021) Wong, Felix; Wilson, Sean; Helbig, Ralf; Hegde, Smitha; Aftenieva, Olha; Zheng, Hai; Liu, Chenli; Pilizota, Teuta; Garner, Ethan C.; Amir, Ariel; Renner, Lars D.
    Mechanical rupture, or lysis, of the cytoplasmic membrane is a common cell death pathway in bacteria occurring in response to β-lactam antibiotics. A better understanding of the cellular design principles governing the susceptibility and response of individual cells to lysis could indicate methods of potentiating β-lactam antibiotics and clarify relevant aspects of cellular physiology. Here, we take a single-cell approach to bacterial cell lysis to examine three cellular features-turgor pressure, mechanosensitive channels, and cell shape changes-that are expected to modulate lysis. We develop a mechanical model of bacterial cell lysis and experimentally analyze the dynamics of lysis in hundreds of single Escherichia coli cells. We find that turgor pressure is the only factor, of these three cellular features, which robustly modulates lysis. We show that mechanosensitive channels do not modulate lysis due to insufficiently fast solute outflow, and that cell shape changes result in more severe cellular lesions but do not influence the dynamics of lysis. These results inform a single-cell view of bacterial cell lysis and underscore approaches of combatting antibiotic tolerance to β-lactams aimed at targeting cellular turgor.
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    4D 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, Leonid
    In 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.