TY - JOUR A1 - Farhan, Muhammad A1 - Chaudhary, Deeptangshu A1 - Nöchel, Ulrich A1 - Behl, Marc A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Electrical actuation of coated and composite fibers based on poly[ethylene-co-(vinyl acetate)] JF - Macromolecular materials and engineering N2 - Robots are typically controlled by electrical signals. Resistive heating is an option to electrically trigger actuation in thermosensitive polymer systems. In this study electrically triggerable poly[ethylene-co-(vinyl acetate)] (PEVA)-based fiber actuators are realized as composite fibers as well as polymer fibers with conductive coatings. In the coated fibers, the core consists of crosslinked PEVA (cPEVA), while the conductive coating shell is achieved via a dip coating procedure with a coating thickness between 10 and 140 mu m. The conductivity of coated fibers sigma = 300-550 S m(-1) is much higher than that of the composite fibers sigma = 5.5 S m(-1). A voltage (U) of 110 V is required to heat 30 cm of coated fiber to a targeted temperature of approximate to 65 degrees C for switching in less than a minute. Cyclic electrical actuation investigations reveal epsilon '(rev) = 5 +/- 1% reversible change in length for coated fibers. The fabrication of such electro-conductive polymeric actuators is suitable for upscaling so that their application potential as artificial muscles can be explored in future studies. KW - artificial muscles KW - fiber actuators KW - resistive heating KW - shape‐memory polymer actuators KW - soft robotics Y1 - 2020 U6 - https://doi.org/10.1002/mame.202000579 SN - 1438-7492 SN - 1439-2054 VL - 306 IS - 2 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Lood, Kajsa A1 - Schmidt, Bernd T1 - Stereoselective synthesis of conjugated polyenes based on tethered olefin metathesis and carbonyl olefination BT - application to the total synthesis of (+)-bretonin B JF - The journal of organic chemistry N2 - The combination of a highly stereoselective tethered olefin metathesis reaction and a Julia-Kocienski olefination is presented as a strategy for the synthesis of conjugated polyenes with at least one Z-configured C=C bond. The strategy is exemplified by the synthesis of the marine natural product (+)-bretonin B. KW - absolute-configuration KW - natural-products KW - formal synthesis KW - oxidation KW - derivatives KW - aldehydes KW - catalysts KW - alcohols KW - sponge KW - ethers Y1 - 2020 U6 - https://doi.org/10.1021/acs.joc.0c00446 SN - 0022-3263 SN - 1520-6904 VL - 85 IS - 7 SP - 5122 EP - 5130 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wessig, Pablo A1 - Freyse, Daniel A1 - Schuster, David A1 - Kelling, Alexandra T1 - Fluorescent dyes with large stokes shifts based on Benzo[1,2-d:4,5-d']bis([1,3]dithiole) (“S4-DBD Dyes”) JF - Europan journal of organic chemistry N2 - We report on a further development of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes by replacement of the four oxygen atoms of the heterocyclic core by sulfur atoms. This variation causes striking changes of the photophysical properties. Whereas absorption and emission significantly shifted to longer wavelength, the fluorescence lifetimes and quantum yields are diminished compared to DBD dyes. The latter effect is presumably caused by an enhanced intersystem crossing to the triplet state due to the sulfur atoms. The very large Stokes shifts of the S-4-DBD dyes ranging from 3000 cm(-1) to 7400 cm(-1) (67 nm to 191 nm) should be especially emphasized. By analogy with DBD dyes a broad variation of absorption and emission wavelength is possible by introducing different electron withdrawing substituents. Moreover, some derivatives for coupling with biomolecules were developed. KW - fluorescent dyes KW - sulfur KW - heterocycles KW - stokes shift KW - photophysics Y1 - 2020 U6 - https://doi.org/10.1002/ejoc.202000093 SN - 1434-193X SN - 1099-0690 VL - 2020 IS - 11 SP - 1732 EP - 1744 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Haubitz, Toni A1 - Fudickar, Werner A1 - Linker, Torsten A1 - Kumke, Michael Uwe T1 - pH-sensitive fluorescence switching of pyridylanthracenes BT - the effect of the isomeric pattern JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - 9,10-substituted anthracenes are known for their useful optical properties like fluorescence, which makes them frequently used probes in sensing applications. In this article, we investigate the fundamental photophysical properties of three pyridyl-substituted variants. The nitrogen atoms in the pyridinium six-membered rings are located in the ortho-, meta-, and para-positions in relation to the anthracene core. Absorption, fluorescence, and transient absorption measurements were carried out and were complemented by theoretical calculations. We monitored the photophysics of the anthracene derivatives in chloroform and water investigating the protonated as well as their nonprotonated forms. We found that the optical properties of the nonprotonated forms are strongly determined by the anthracene chromophore, with only small differences to other 9,10-substituted anthracenes, for example diphenyl anthracene. In contrast, protonation leads to a strong decrease in fluorescence intensity and lifetime. Transient absorption measurements and theoretical calculations revealed the formation of a charge-transfer state in the protonated chromophores, where electron density is shifted from the anthracene moiety toward the protonated pyridyl substituents. While the para- and ortho-derivatives' charge transfer is still moderately fluorescent, the meta-derivative is affected much stronger and shows nearly no fluorescence. This nitrogen-atom-position-dependent sensitivity to hydronium activity makes a combination of these fluorophores very attractive for pH-sensing applications covering a broadened pH range. KW - Absorption KW - Aromatic compounds KW - Fluorescence KW - Hydrocarbons KW - Reaction mechanisms Y1 - 2020 U6 - https://doi.org/10.1021/acs.jpca.0c09911 SN - 1089-5639 SN - 1520-5215 VL - 124 IS - 52 SP - 11017 EP - 11024 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schultze, Christiane A1 - Foß, Stefan A1 - Schmidt, Bernd T1 - 8-Prenylflavanones through microwave promoted tandem claisen rearrangement/6-endo-trig cyclization and cross metathesis JF - European journal of organic chemistry N2 - Prenylated flavanones were obtained from ortho-allyloxy chalcones through a one-pot sequence of Claisen rearrangement and 6-endo-trig cyclization, followed by olefin cross metathesis of the intermediate allyl flavanones with 2-methyl-2-butene. The synthetic utility of this route is illustrated for the synthesis of several naturally occurring prenyl flavanones. KW - tandem reactions KW - arenes KW - oxygen heterocycles KW - microwave chemistry KW - rearrangement Y1 - 2020 U6 - https://doi.org/10.1002/ejoc.202001378 SN - 1434-193X SN - 1099-0690 VL - 2020 IS - 47 SP - 7373 EP - 7384 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mai-Linde, Yasemin A1 - Linker, Torsten T1 - Radical clock probes to determine carbohydrate radical stabilities JF - Organic letters N2 - Carbohydrate radical stabilities in the 1- and 2-position have been determined by a radical clock approach, starting from cyclopropanated sugars with xanthates as precursors. Various hexoses and pentoses afforded 1-deoxy sugars as main products, indicating that anomeric radicals are more stable than radicals in the 2-position. An additional influence of the configurations on radical stabilities has been observed. Our results should be interesting for the understanding of 1,2-radical rearrangements in carbohydrate chemistry and offer an easy access to deoxy-vinyl sugars. KW - stereoselective-synthesis KW - convenient synthesis KW - chemistry KW - cyclopropanation KW - mechanism KW - glycals KW - beta-(acyloxy)alkylrear KW - rangement KW - sugars Y1 - 2020 U6 - https://doi.org/10.1021/acs.orglett.0c00111 SN - 1523-7060 SN - 1523-7052 VL - 22 IS - 4 SP - 1525 EP - 1529 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Glatzel, Julia A1 - Noack, Sebastian A1 - Schanzenbach, Dirk A1 - Schlaad, Helmut T1 - Anionic polymerization of dienes in ‘green’ solvents JF - Polymer international N2 - Isoprene and beta-myrcene were polymerized by anionic polymerization in bulk and in the 'green' ether solvents cyclopentyl methyl ether and 2-methyltetrahydrofuran and, for comparison, in cyclohexane and tetrahydrofuran. The polydienes produced in bulk and in cyclohexane contained high amounts of 1,4 units (>90%) whereas those produced in ether solvents were rich in 1,2 and 3,4 units (36%-86%). Comparison of the microstructures and glass transition temperatures of the polydienes obtained in the various solvents suggests that conventionally used solvents can be substituted by environmentally more friendly alternatives. KW - isoprene KW - β‐myrcene KW - anionic polymerization KW - green KW - solvents KW - microstructure KW - glass transition Y1 - 2020 U6 - https://doi.org/10.1002/pi.6152 SN - 0959-8103 SN - 1097-0126 VL - 70 IS - 2 SP - 181 EP - 184 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bourgat, Yannick A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Menzel, Henning T1 - Enzyme degradable polymersomes from chitosan-g-[poly-l-lysine-block-epsilon-caprolactone] copolymer JF - Macromolecular bioscience N2 - The scope of this study includes the synthesis of chitosan-g-[peptide-poly-epsilon-caprolactone] and its self-assembly into polymeric vesicles employing the solvent shift method. In this way, well-defined core-shell structures suitable for encapsulation of drugs are generated. The hydrophobic polycaprolactone side-chain and the hydrophilic chitosan backbone are linked via an enzyme-cleavable peptide. The synthetic route involves the functionalization of chitosan with maleimide groups and the preparation of polycaprolactone with alkyne end-groups. A peptide functionalized with a thiol group on one side and an azide group on the other side is prepared. Thiol-ene click-chemistry and azide-alkyne Huisgen cycloaddition are then used to link the chitosan and poly-epsilon-caprolactone chains, respectively, with this peptide. For a preliminary study, poly-l-lysin is a readily available and cleavable peptide that is introduced to investigate the feasibility of the system. The size and shape of the polymersomes are studied by dynamic light scattering and cryo-scanning electron microscopy. Furthermore, degradability is studied by incubating the polymersomes with two enzymes, trypsin and chitosanase. A dispersion of polymersomes is used to coat titanium plates and to further test the stability against enzymatic degradation. KW - chitosan KW - click chemistry KW - drug delivery system KW - enzyme KW - polymersomes KW - poly‐ ε ‐ caprolactone Y1 - 2020 U6 - https://doi.org/10.1002/mabi.202000259 SN - 1616-5187 SN - 1616-5195 VL - 21 IS - 1 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wessig, Pablo A1 - John, Leonard A1 - Sperlich, Eric A1 - Kelling, Alexandra T1 - Sulfur tuning of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes JF - European journal of organic chemistry N2 - The replacement of oxygen by sulfur atoms of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes is an efficient way to adjust the photophysical properties (sulfur tuning). While previously developed S-4-DBD dyes exhibit considerably red-shifted absorption and emission wavelength, the heavy atom effect of four sulfur atoms cause low fluorescence quantum yields and short fluorescence lifetimes. Herein, we demonstrate that the replacement of less than four sulfur atoms (S-1-DBD, 1,2-S-2-DBD, and 1,4-S-2-DBD dyes) permits a fine-tuning of the photophysical properties. In some cases, a similar influence on the wavelength without the detrimental effect on the quantum yields and lifetimes is observed. Furthermore, the synthetic accessibility of S-1- and S-2-DBD dyes is improved, compared with S-4-DBD dyes. For coupling with biomolecules a series of reactive derivatives of the new dyes were developed (azides, OSu esters, alkynes, maleimides). KW - fluorescent dyes KW - heterocycles KW - photophysics KW - stokes shift KW - sulfur Y1 - 2020 U6 - https://doi.org/10.1002/ejoc.202001418 SN - 1434-193X SN - 1099-0690 VL - 2021 IS - 3 SP - 499 EP - 511 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Finke, Hannah A1 - Wandt, Viktoria Klara Veronika A1 - Ebert, Franziska A1 - Guttenberger, Nikolaus A1 - Glabonjat, Ronald A. A1 - Stiboller, Michael A1 - Francesconi, Kevin A. A1 - Raber, Georg A1 - Schwerdtle, Tanja T1 - Toxicological assessment of arsenic-containing phosphatidylcholines in HepG2 cells N2 - Arsenolipids include a wide range of organic arsenic species that occur naturally in seafood and thereby contribute to human arsenic exposure. Recently arsenic-containing phosphatidylcholines (AsPCs) were identified in caviar, fish, and algae. In this first toxicological assessment of AsPCs, we investigated the stability of both the oxo- and thioxo-form of an AsPC under experimental conditions, and analyzed cell viability, indicators of genotoxicity and biotransformation in human liver cancer cells (HepG2). Precise toxicity data could not be obtained owing to the low solubility in the cell culture medium of the thioxo-form, and the ease of hydrolysis of the oxo-form, and to a lesser degree the thioxo-form. Hydrolysis resulted amongst others in the respective constituent arsenic-containing fatty acid (AsFA). Incubation of the cells with oxo-AsPC resulted in a toxicity similar to that determined for the hydrolysis product oxo-AsFA alone, and there were no indices for genotoxicity. Furthermore, the oxo-AsPC was readily taken up by the cells resulting in high cellular arsenic concentrations (50 μM incubation: 1112 ± 146 μM As cellular), whereas the thioxo-AsPC was substantially less bioavailable (50 μM incubation: 293 ± 115 μM As cellular). Speciation analysis revealed biotransformation of the AsPCs to a series of AsFAs in the culture medium, and, in the case of the oxo-AsPC, to as yet unidentified arsenic species in cell pellets. The results reveal the difficulty of toxicity studies of AsPCs in vitro, indicate that their toxicity might be largely governed by their arsenic fatty acid content and suggest a multifaceted human metabolism of food derived complex arsenolipids. KW - Biochemistry KW - Biological Sciences KW - Science and Mathematics KW - Books KW - Journals Y1 - 2020 U6 - https://doi.org/10.1039/d0mt00073f VL - 12 IS - 7 SP - 1159 EP - 1170 PB - Oxford University CY - Cambridge ER - TY - JOUR A1 - von Zander, Robert Edler A1 - Saalfrank, Peter T1 - On the borate-catalyzed electrochemical reduction of phosphine oxide BT - a computational study JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Recently, Nocera and co-workers (J. Am. Chem. Soc. 2018, 140, 13711) demonstrated that triaryl borate Lewis acids facilitate the direct electrochemical reduction of triphenylphosphine oxide (TPPO) to triphenylphosphine (TPP). In the present contribution, we report a quantum chemical study unravelling details of the reaction, which also supports the proposed ECrECi mechanism. Alternative electrochemical routes to TPPO reduction facilitated by other Lewis acids (CH3+), or by photocatalysis at semiconductor surfaces, are also briefly discussed. Y1 - 2020 U6 - https://doi.org/10.1021/acs.jpca.0c07805 SN - 1089-5639 SN - 1520-5215 VL - 124 IS - 49 SP - 10239 EP - 10245 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kochovski, Zdravko A1 - Chen, Guosong A1 - Yuan, Jiayin A1 - Lu, Yan T1 - Cryo-Electron microscopy for the study of self-assembled poly(ionic liquid) nanoparticles and protein supramolecular structures JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - Cryo-electron microscopy (cryo-EM) is a powerful structure determination technique that is well-suited to the study of protein and polymer self-assembly in solution. In contrast to conventional transmission electron microscopy (TEM) sample preparation, which often times involves drying and staining, the frozen-hydrated sample preparation allows the specimens to be kept and imaged in a state closest to their native one. Here, we give a short overview of the basic principles of Cryo-EM and review our results on applying it to the study of different protein and polymer self-assembled nanostructures. More specifically, we show how we have applied cryo-electron tomography (cryo-ET) to visualize the internal morphology of self-assembled poly(ionic liquid) nanoparticles and cryo-EM single particle analysis (SPA) to determine the three-dimensional (3D) structures of artificial protein microtubules. KW - self-assembly KW - poly(ionic liquid) nanoparticles KW - protein self-assembly KW - cryo-electron microscopy KW - single particle analysis KW - cryo-electron KW - tomography Y1 - 2020 U6 - https://doi.org/10.1007/s00396-020-04657-w SN - 0303-402X SN - 1435-1536 VL - 298 IS - 7 SP - 707 EP - 717 PB - Springer CY - New York ER - TY - JOUR A1 - Ebert, Franziska A1 - Ziemann, Vanessa A1 - Wandt, Viktoria Klara Veronika A1 - Witt, Barbara A1 - Müller, Sandra Marie A1 - Guttenberger, Nikolaus A1 - Bankoglu, Ezgi Eyluel A1 - Stopper, Helga A1 - Raber, Georg A1 - Francesconi, Kevin A. A1 - Schwerdtle, Tanja T1 - Cellular toxicological characterization of a thioxolated arsenic-containing hydrocarbon JF - Journal of trace elements in medicine and biology N2 - Arsenolipids, especially arsenic-containing hydrocarbons (AsHC), are an emerging class of seafood originating contaminants. Here we toxicologically characterize a recently identified oxo-AsHC 332 metabolite, thioxo-AsHC 348 in cultured human liver (HepG2) cells. Compared to results of previous studies of the parent compound oxo-AsHC 332, thioxo-AsHC 348 substantially affected cell viability in the same concentration range but exerted about 10-fold lower cellular bioavailability. Similar to oxo-AsHC 332, thioxo-AsHC 348 did not substantially induce oxidative stress nor DNA damage. Moreover, in contrast to oxo-AsHC 332 mitochondria seem not to be a primary subcellular toxicity target for thioxo-AsHC 348. This study indicates that thioxo-AsHC 348 is at least as toxic as its parent compound oxo-AsHC 332 but very likely acts via a different mode of toxic action, which still needs to be identified. Y1 - 2017 U6 - https://doi.org/10.1016/j.jtemb.2020.126563 VL - 61 PB - Elsevier CY - München ER - TY - JOUR A1 - Finke, Hannah A1 - Winkelbeiner, Nicola Lisa A1 - Lossow, Kristina A1 - Hertel, Barbara A1 - Wandt, Viktoria Klara Veronika A1 - Schwarz, Maria A1 - Pohl, Gabriele A1 - Kopp, Johannes Florian A1 - Ebert, Franziska A1 - Kipp, Anna Patricia A1 - Schwerdtle, Tanja T1 - Effects of a Cumulative, Suboptimal Supply of Multiple Trace Elements in Mice BT - trace element status, genomic stability, inflammation, and epigenetics JF - Molecular nutrition & food research N2 - Scope: Trace element (TE) deficiencies often occur accumulated, as nutritional intake is inadequate for several TEs, concurrently. Therefore, the impact of a suboptimal supply of iron, zinc, copper, iodine, and selenium on the TE status, health parameters, epigenetics, and genomic stability in mice are studied. Methods and results: Male mice receive reduced or adequate amounts of TEs for 9 weeks. The TE status is analyzed mass‐spectrometrically in serum and different tissues. Furthermore, gene and protein expression of TE biomarkers are assessed with focus on liver. Iron concentrations are most sensitive toward a reduced supply indicated by increased serum transferrin levels and altered hepatic expression of iron‐related genes. Reduced TE supply results in smaller weight gain but higher spleen and heart weights. Additionally, inflammatory mediators in serum and liver are increased together with hepatic genomic instability. However, global DNA (hydroxy)methylation is unaffected by the TE modulation. Conclusion: Despite homeostatic regulation of most TEs in response to a low intake, this condition still has substantial effects on health parameters. It appears that the liver and immune system react particularly sensitive toward changes in TE intake. The reduced Fe status might be the primary driver for the observed effects. Y1 - 2020 U6 - https://doi.org/10.1002/mnfr.202000325 SN - 1613-4125 VL - 64 IS - 16 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schneider, Matthias A1 - Fritzsche, Nora A1 - Puciul-Malinowska, Agnieszka A1 - Balis, Andrzej A1 - Mostafa, Amr A1 - Bald, Ilko A1 - Zapotoczny, Szczepan A1 - Taubert, Andreas T1 - Surface etching of 3D printed poly(lactic acid) with NaOH: a systematic approach JF - Polymers N2 - The article describes a systematic investigation of the effects of an aqueous NaOH treatment of 3D printed poly(lactic acid) (PLA) scaffolds for surface activation. The PLA surface undergoes several morphology changes and after an initial surface roughening, the surface becomes smoother again before the material dissolves. Erosion rates and surface morphologies can be controlled by the treatment. At the same time, the bulk mechanical properties of the treated materials remain unaltered. This indicates that NaOH treatment of 3D printed PLA scaffolds is a simple, yet viable strategy for surface activation without compromising the mechanical stability of PLA scaffolds. KW - surface modification KW - sodium hydroxide etching KW - poly(lactic acid) KW - 3D printing KW - roughness KW - wettability KW - erosion Y1 - 2020 VL - 12 IS - 8 PB - MDPI CY - Basel ER - TY - THES A1 - Bhaskar, Thanga Bhuvanesh Vijaya T1 - Biomimetic layers of extracellular matrix glycoproteins as designed biointerfaces N2 - The goal of regenerative medicine is to guide biological systems towards natural healing outcomes using a combination of niche-specific cells, bioactive molecules and biomaterials. In this regard, mimicking the extracellular matrix (ECM) surrounding cells and tissues in vivo is an effective strategy to modulate cell behaviors. Cellular function and phenotype is directed by the biochemical and biophysical signals present in the complex 3D network of ECMs composed mainly of glycoproteins and hydrophilic proteoglycans. While cellular modulation in response to biophysical cues emulating ECM features has been investigated widely, the influence of biochemical display of ECM glycoproteins mimicking their presentation in vivo is not well characterized. It remains a significant challenge to build artificial biointerfaces using ECM glycoproteins that precisely match their presentation in nature in terms of morphology, orientation and conformation. This challenge becomes clear, when one understands how ECM glycoproteins self-assemble in the body. Glycoproteins produced inside the cell are secreted in the extra-cellular space, where they are bound to the cell membrane or other glycoproteins by specific interactions. This leads to elevated local concentration and 2Dspatial confinement, resulting in self-assembly by the reciprocal interactions arising from the molecular complementarity encoded in the glycoprotein domains. In this thesis, air-water (A-W) interface is presented as a suitable platform, where self-assembly parameters of ECM glycoproteins such as pH, temperature and ionic strength can be controlled to simulate in vivo conditions (Langmuir technique), resulting in the formation of glycoprotein layers with defined characteristics. The layer can be further compressed with surface barriers to enhance glycoprotein-glycoprotein contacts and defined layers of glycoproteins can be immobilized on substrates by horizontal lift and touch method, called Langmuir-Schäfer (LS) method. Here, the benefit of Langmuir and LS methods in achieving ECM glycoprotein biointerfaces with controlled network morphology and ligand density on substrates is highlighted and contrasted with the commonly used (glyco)protein solution deposition (SO) method on substrates. In general, the (glyco)protein layer formation by SO is rather uncontrolled, influenced strongly by (glyco)protein-substrate interactions and it results in multilayers and aggregations on substrates, while the LS method results in (glyco)proteins layers with a more homogenous presentation. To achieve the goal of realizing defined ECM layers on substrates, ECM glycoproteins having the ability to self-assemble were selected: Collagen-IV (Col-IV) and fibronectin (FN). Highly packed FN layer with uniform presentation of ligands was deposited on polydimethysiloxane VIII (PDMS) by LS method, while a heterogeneous layer was formed on PDMS by SO with prominent aggregations visible. Mesenchymal stem cells (MSC) on PDMS equipped with FN by LS exhibited more homogeneous and elevated vinculin expression and weaker stress fiber formation than on PDMS equipped with FN by SO and these divergent responses could be attributed to the differences in glycoprotein presentation at the interface. Col-IV are scaffolding components of specialized ECM called basement membranes (BM), and have the propensity to form 2D networks by self-polymerization associated with cells. Col- IV behaves as a thin-disordered network at the A-W interface. As the Col-IV layer was compressed at the A-W interface using trough barriers, there was negligible change in thickness (layer thickness ~ 50 nm) or orientation of molecules. The pre-formed organization of Col-IV was transferred by LS method in a controlled fashion onto substrates meeting the wettability criterion (CA ≤ 80°). MSC adhesion (24h) on PET substrates deposited with Col-IV LS films at 10, 15 and 20 mN·m-1 surface pressures was (12269.0 ± 5856.4) cells for LS10, (16744.2 ± 1280.1) cells for LS15 and (19688.3 ± 1934.0) cells for LS20 respectively. Remarkably, by selecting the surface areal density of Col-IV on the Langmuir trough on PET, there is a linear increase between the number of adherent MSCs and the Col-IV ligand density. Further, FN has the ability to self-stabilize and form 2D networks (even without compression) while preserving native β-sheet structure at the A-W interface on a defined subphase (pH = 2). This provides the possibility to form such layers on any vessel (even on standard six-well culture plates) and the cohesive FN layers can be deposited by LS transfer, without the need for expensive LB instrumentation. Multilayers of FN can be immobilized on substrates by this approach, as easily as Layer-by-Layer method, even without the need for secondary adlayer or activated bare substrate. Thus, this facile glycoprotein coating strategy approach is accessible to many researchers to realize defined FN films on substrates for cell culture. In conclusion, Langmuir and LS methods can create biomimetic glycoprotein biointerfaces on substrates controlling aspects of presentation such as network morphology and ligand density. These methods will be utilized to produce artificial BM mimics and interstitial ECM mimics composed of more than one ECM glycoprotein layer on substrates, serving as artificial niches instructing stem cells for cell-replacement therapies in the future. N2 - Ziel der regenerativen Medizin ist es, Regenerationsprozesse in biologischen Systemen mit Hilfe von nischenspezifischen Zellen, bioaktiven Molekülen und Biomaterialien zu modulieren. In diesem Zusammenhang ist die Nachahmung der extrazellulären Matrix (ECM), die Zellen und Gewebe in vivo umgibt, eine wirksame Strategie zur Modulation des Zellverhaltens. Die zelluläre Funktion und der Phänotyp werden durch die biochemischen und biophysikalischen Signale gesteuert, die in dem komplexen 3D-Netzwerk von ECMs vorhanden sind, welches hauptsächlich aus Glykoproteinen und hydrophilen Proteoglykanen besteht. Während die zelluläre Modulation als Reaktion auf biophysikalische Signale, die ECM-Merkmale nachahmen, umfassend untersucht wurde, ist der Einfluss der biochemischen Charakterisierung von ECM-Glykoproteinen, die deren Darstellung in vivo nachahmen, nicht gut charakterisiert. Es bleibt eine bedeutende Herausforderung, künstliche Biogrenzflächen mit ECM-Glykoproteinen zu schaffen, die in Bezug auf Morphologie, Orientierung und Konformation genau ihrer Darstellung in der Natur entsprechen. Diese Herausforderung wird deutlich, wenn man versteht, wie sich die ECM-Glykoproteine im Körper selbst zusammensetzen. Glykoproteine, die im Inneren der Zelle produziert werden, werden im extrazellulären Raum ausgeschieden, wo sie durch spezifische Interaktionen an die Zellmembran oder andere Glykoproteine gebunden werden. Dies führt zu einer erhöhten lokalen Konzentration und zweidimensionalen Raumbegrenzung, was durch die wechselseitigen Wechselwirkungen, die sich aus der in den Glykoprotein-Domänen kodierten molekularen Komplementarität ergeben, zur Selbstorganisation führt. In dieser Arbeit wird die Luft-Wasser (A-W)-Grenzfläche als eine geeignete Umgebung vorgestellt, mit der die Selbstorganisationsparameter von ECM-Glykoproteinen wie pH-Wert, Temperatur und Ionenstärke kontrolliert werden können, um in vivo-Bedingungen zu simulieren (Langmuir-Technik), was zur Bildung von Glykoproteinschichten mit definierten Eigenschaften führt. Die Schicht kann mit Oberflächenbarrieren weiter komprimiert werden, um die Glykoprotein-Glykoprotein-Kontakte zu verstärken, und definierte Schichten von Glykoproteinen können auf Substraten durch eine horizontale Hebe- und Berührungsmethode, sie sogenannte Langmuir-Schäfer (LS)-Methode, immobilisiert werden. Hier wird der Vorteil der Langmuir- und LS-Methode bei der Erzielung von ECM-Glykoprotein-Biogrenzflächen mit kontrollierter Netzwerkmorphologie und Ligandendichte auf Oberflächen hervorgehoben und mit der üblicherweise verwendeten Methode der (Glyko)Protein-Lösungsabscheidung (SO) auf Oberflächen gegenübergestellt. Im Allgemeinen ist die (Glyko)ProteinX Schichtbildung durch SO eher unkontrolliert, wird stark durch (Glyko)Protein-Substrat- Wechselwirkungen beeinflusst und führt zu Mehrfachschichten und Ansammlungen auf Oberflächen, während die LS-Methode zu (Glyko)Protein-Schichten mit einer homogeneren Darstellung führt. Um definierte ECM-Schichten auf Oberflächen zu erzeugen, wurden ECM-Glykoproteine mit der Fähigkeit zur Selbstorganisation ausgewählt: Kollagen-IV (Col-IV) und Fibronektin (FN). Eine dicht gepackte FN-Schicht mit gleichmäßiger Verteilung der Liganden wurde mit der LSMethode auf Polydimethysiloxan (PDMS) aufgetragen, während auf PDMS mit SO eine heterogene Schicht mit klar erkennbaren Verdichtungen gebildet wurde. Mesenchymale Stammzellen (MSC) auf PDMS, denen FN nach der LS-Methode hinzugefügt wurde, wiesen eine homogenere und erhöhte Vinculin-Expression und eine schwächere Stressfaserbildung auf als MSC Stammzellen auf PDMS, dem FN nach der SO-Methode hinzugefügt wurde, und diese verschiedenen Reaktionen konnten auf die Unterschiede in der Glykoprotein-Verteilung an der Grenzfläche zurückgeführt werden. Col-IV ist eine Komponente spezialisierter ECMs, die Basalmembranen (BM) genannt werden, und neigen zur Bildung von 2D-Netzwerke durch Selbstpolymerisation, die mit Zellen assoziiert sind. Col-IV verhält sich wie ein dünnes ungeordnetes Netzwerk an der A-WGrenzfläche. Während die Col-IV-Schicht an der A-W-Grenzfläche mit Hilfe von Trogbarrieren zusammengerückt wurde, gab es eine vernachlässigbare Änderung der Dicke (Schichtdicke ~ 50 nm) oder der Orientierung der Moleküle. Die vorgeformte Organisation von Col-IV wurde mit der LS-Methode kontrolliert auf Oberflächen aufgetragen, die das Kriterium der Benetzbarkeit erfüllten (CA ≤ 80°). Die MSC-Adhäsion (24h) auf Polyethylenterephthalat (PET)-Oberflächen, die mit Col-IV LS-Folien bei Oberflächendrücken von 10, 15 und 20 mN·m-1 aufgebracht wurden, waren (12269,0 ± 5856,4) Zellen für LS10, (16744,2 ± 1280,1) Zellen für LS15 (19688,3 ± 1934,0) Zellen für LS20. Bemerkenswert ist dabei, dass durch die Auswahl der Oberflächen-Flächendichte von Col-IV am Langmuir-Trog auf PET ein linearer Anstieg zwischen der Anzahl der adhärenten MSCs und der Col-IV-Ligandendichte erfolgt. Auch FN die Fähigkeit, sich selbst zu stabilisieren und 2D-Netzwerke zu bilden (sogar ohne Kompression), während die native β-Faltblattstruktur an der A-W-Grenzfläche auf einer definierten Subphase (pH = 2) erhalten bleibt. Dies bietet die Möglichkeit, solche Schichten auf jedem beliebigen Gefäß (sogar auf Platten mit Standard-Six-Well-Kulturen) zu bilden, und die kohäsiven FN-Schichten können durch LS-Transfer abgelagert werden, ohne dass eine teure LB-Instrumentierung erforderlich ist. Mehrfachschichten aus FN können auf diese Weise XI auf Oberflächen immobilisiert werden, genauso einfach wie bei der Layer-by-Layer-Methode, auch ohne die Notwendigkeit einer zweiten adsorbierenden Schicht oder einer aktivierten blanken Oberfläche. Somit ist dieser Ansatz einer einfachen Glykoprotein- Beschichtungsstrategie vielen Forschern zugänglich, um definierte FN-Filme auf Oberflächen für die Zellkultur zu realisieren. Zusammenfassend lässt sich sagen, dass Langmuir- und LSMethoden biomimetische Glykoprotein-Bioschnittstellen auf Oberflächen erzeugen können, die makroskopische Darstellungen wie Netzwerkmorphologie und Ligandendichte kontrollieren. Diese Methoden werden genutzt, um künstliche BM und ECM zu generieren, die aus mehr als einer Glykoproteinschicht bestehen. Diese können dann als künstliche Nischen für Stammzellen, die in zukünftigen Zellersatztherapien zum Einsatz kommen könnte. KW - Extracellular Matrix KW - Biomimetics KW - Glycoproteins KW - Langmuir-Schaefer method KW - Designed Biointerfaces KW - Extrazelluläre Matrix KW - Biomimetik KW - Glykoproteine KW - Langmuir-Schäfer-Methode KW - Designte Biointerface Y1 - 2020 ER - TY - JOUR A1 - Bechmann, Wolfgang A1 - Bald, Ilko T1 - Chemische Thermodynamik JF - Einstieg in die Physikalische Chemie für Naturwissenschaftler N2 - Der Begriff Thermodynamik ist von den griechischen Wörtern ϑερμος (warm) und δυναμις (Kraft) abgeleitet. Er steht für das Teilgebiet der Physik (Wärmelehre), das sich vor allem mit der Umwandlung von Wärmeenergie in andere Energieformen bei physikalischen Vorgängen befasst. Y1 - 2020 SN - 978-3-662-62034-2 SN - 978-3-662-62033-5 U6 - https://doi.org/10.1007/978-3-662-62034-2_1 SP - 13 EP - 140 PB - Springer CY - Berlin ET - 7. Auflage ER - TY - JOUR A1 - Bechmann, Wolfgang A1 - Bald, Ilko T1 - Lösungen JF - Einstieg in die Physikalische Chemie für Naturwissenschaftler N2 - In diesem Kapitel finden Sie die Lösungen zu den Übungsaufgaben. Y1 - 2020 SN - 978-3-662-62033-5 SN - 978-3-662-62034-2 U6 - https://doi.org/10.1007/978-3-662-62034-2_5 SP - 459 EP - 492 PB - Springer CY - Berlin ET - 7. Auflage ER - TY - BOOK A1 - Bechmann, Wolfgang A1 - Bald, Ilko T1 - Einstieg in die Physikalische Chemie für Naturwissenschaftler T3 - Studienbücher Chemie Lehrbuch N2 - Der Einstieg in die Physikalische Chemie für Naturwissenschaftler Einführung in die Grundlagen der Spektroskopie und der wichtigsten Methoden der Stoff- und Strukturanalytik Mit Übungsaufgaben und allen Lösungen inkl. der Lösungswege Enthält Anleitungen für Praktikumsversuche Y1 - 2020 SN - 978-3-662-62033-5 SN - 978-3-662-62034-2 U6 - https://doi.org/10.1007/978-3-662-62034-2 PB - Springer CY - Berlin ET - 7. Auflage ER - TY - JOUR A1 - Bechmann, Wolfgang A1 - Bald, Ilko T1 - Reaktionskinetik JF - Einstieg in die Physikalische Chemie für Naturwissenschaftler N2 - Bei der Untersuchung chemischer Reaktionen interessiert zunächst, welche Reaktionsprodukte aus gegebenen Ausgangsstoffen gebildet werden können. Wichtig sind weiterhin Angaben zum möglichen Grad der Umsetzung der Ausgangsstoffe und zur Energiebilanz einer Reaktion. Damit sind aber noch keine Aussagen über den zeitlichen Ablauf der Stoffumwandlung getroffen. Y1 - 2020 SN - 978-3-662-62033-5 SN - 978-3-662-62034-2 U6 - https://doi.org/10.1007/978-3-662-62034-2_2 SP - 141 EP - 220 PB - Springer CY - Berlin ET - 7. Auflage ER -