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- ItemSuperelasticity of Plasma- and Synthetic Membranes Resulting from Coupling of Membrane Asymmetry, Curvature, and Lipid Sorting(Weinheim : Wiley-VCH, 2021) Steinkühler, Jan; Fonda, Piermarco; Bhatia, Tripta; Zhao, Ziliang; Leomil, Fernanda S. C.; Lipowsky, Reinhard; Dimova, RumianaBiological cells are contained by a fluid lipid bilayer (plasma membrane, PM) that allows for large deformations, often exceeding 50% of the apparent initial PM area. Isolated lipids self-organize into membranes, but are prone to rupture at small (<2–4%) area strains, which limits progress for synthetic reconstitution of cellular features. Here, it is shown that by preserving PM structure and composition during isolation from cells, vesicles with cell-like elasticity can be obtained. It is found that these plasma membrane vesicles store significant area in the form of nanotubes in their lumen. These act as lipid reservoirs and are recruited by mechanical tension applied to the outer vesicle membrane. Both in experiment and theory, it is shown that a “superelastic” response emerges from the interplay of lipid domains and membrane curvature. This finding allows for bottom-up engineering of synthetic biomaterials that appear one magnitude softer and with threefold larger deformability than conventional lipid vesicles. These results open a path toward designing superelastic synthetic cells possessing the inherent mechanics of biological cells.
- ItemGas Plasma Technology Augments Ovalbumin Immunogenicity and OT-II T Cell Activation Conferring Tumor Protection in Mice(Weinheim : Wiley-VCH, 2021) Clemen, Ramona; Freund, Eric; Mrochen, Daniel; Miebach, Lea; Schmidt, Anke; Rauch, Bernhard H.; Lackmann, Jan‐Wilm; Martens, Ulrike; Wende, Kristian; Lalk, Michael; Delcea, Mihaela; Bröker, Barbara M.; Bekeschus, SanderReactive oxygen species (ROS/RNS) are produced during inflammation and elicit protein modifications, but the immunological consequences are largely unknown. Gas plasma technology capable of generating an unmatched variety of ROS/RNS is deployed to mimic inflammation and study the significance of ROS/RNS modifications using the model protein chicken ovalbumin (Ova vs oxOva). Dynamic light scattering and circular dichroism spectroscopy reveal structural modifications in oxOva compared to Ova. T cells from Ova-specific OT-II but not from C57BL/6 or SKH-1 wild type mice presents enhanced activation after Ova addition. OxOva exacerbates this activation when administered ex vivo or in vivo, along with an increased interferon-gamma production, a known anti-melanoma agent. OxOva vaccination of wild type mice followed by inoculation of syngeneic B16F10 Ova-expressing melanoma cells shows enhanced T cell number and activation, decreased tumor burden, and elevated numbers of antigen-presenting cells when compared to their Ova-vaccinated counterparts. Analysis of oxOva using mass spectrometry identifies three hot spots regions rich in oxidative modifications that are associated with the increased T cell activation. Using Ova as a model protein, the findings suggest an immunomodulating role of multi-ROS/RNS modifications that may spur novel research lines in inflammation research and for vaccination strategies in oncology.
- ItemIn Situ Fabrication of Freestanding Single-Atom-Thick 2D Metal/Metallene and 2D Metal/ Metallene Oxide Membranes: Recent Developments(Weinheim : Wiley-VCH, 2021) Ta, Huy Q.; Mendes, Rafael G.; Liu, Yu; Yang, Xiaoqin; Luo, Jingping; Bachmatiuk, Alicja; Gemming, Thomas; Zeng, Mengqi; Fu, Lei; Liu, Lijun; Rümmeli, Mark H.In recent years, two-dimensional (2D) materials have attracted a lot of research interest as they exhibit several fascinating properties. However, outside of 2D materials derived from van der Waals layered bulk materials only a few other such materials are realized, and it remains difficult to confirm their 2D freestanding structure. Despite that, many metals are predicted to exist as 2D systems. In this review, the authors summarize the recent progress made in the synthesis and characterization of these 2D metals, so called metallenes, and their oxide forms, metallene oxides as free standing 2D structures formed in situ through the use of transmission electron microscopy (TEM) and scanning TEM (STEM) to synthesize these materials. Two primary approaches for forming freestanding monoatomic metallic membranes are identified. In the first, graphene pores as a means to suspend the metallene or metallene oxide and in the second, electron-beam sputtering for the selective etching of metal alloys or thick complex initial materials is employed to obtain freestanding single-atom-thick 2D metal. The data show a growing number of 2D metals/metallenes and 2D metal/ metallene oxides having been confirmed and point to a bright future for further discoveries of these 2D materials.
- ItemHigh-Quality Graphene Using Boudouard Reaction(Weinheim : Wiley-VCH, 2022) Grebenko, Artem K.; Krasnikov, Dmitry V.; Bubis, Anton V.; Stolyarov, Vasily S.; Vyalikh, Denis V.; Makarova, Anna A.; Fedorov, Alexander; Aitkulova, Aisuluu; Alekseeva, Alena A.; Gilshtein, Evgeniia; Bedran, Zakhar; Shmakov, Alexander N.; Alyabyeva, Liudmila; Mozhchil, Rais N.; Ionov, Andrey M.; Gorshunov, Boris P.; Laasonen, Kari; Podzorov, Vitaly; Nasibulin, Albert G.Following the game-changing high-pressure CO (HiPco) process that established the first facile route toward large-scale production of single-walled carbon nanotubes, CO synthesis of cm-sized graphene crystals of ultra-high purity grown during tens of minutes is proposed. The Boudouard reaction serves for the first time to produce individual monolayer structures on the surface of a metal catalyst, thereby providing a chemical vapor deposition technique free from molecular and atomic hydrogen as well as vacuum conditions. This approach facilitates inhibition of the graphene nucleation from the CO/CO2 mixture and maintains a high growth rate of graphene seeds reaching large-scale monocrystals. Unique features of the Boudouard reaction coupled with CO-driven catalyst engineering ensure not only suppression of the second layer growth but also provide a simple and reliable technique for surface cleaning. Aside from being a novel carbon source, carbon monoxide ensures peculiar modification of catalyst and in general opens avenues for breakthrough graphene-catalyst composite production.
- ItemCharge‐Compensated N‐Doped π ‐Conjugated Polymers: Toward both Thermodynamic Stability of N‐Doped States in Water and High Electron Conductivity(Weinheim : Wiley-VCH, 2022) Borrmann, Fabian; Tsuda, Takuya; Guskova, Olga; Kiriy, Nataliya; Hoffmann, Cedric; Neusser, David; Ludwigs, Sabine; Lappan, Uwe; Simon, Frank; Geisler, Martin; Debnath, Bipasha; Krupskaya, Yulia; Al‐Hussein, Mahmoud; Kiriy, AntonThe understanding and applications of electron-conducting π-conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n-doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n-doped backbone. Here, the n-type conducting NDI polymer with enhanced stability of its n-doped states for prospective “in-water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping-induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n-doped states in water and the high electron conductivity of polymers.
- ItemChemokine‐Capturing Wound Contact Layer Rescues Dermal Healing(Weinheim : Wiley-VCH, 2021) Schirmer, Lucas; Atallah, Passant; Freudenberg, Uwe; Werner, CarstenExcessive inflammation often impedes the healing of chronic wounds. Scavenging of chemokines by multiarmed poly(ethylene glycol)-glycosaminoglycan (starPEG-GAG) hydrogels has recently been shown to support regeneration in a diabetic mouse chronic skin wound model. Herein, a textile-starPEG-GAG composite wound contact layer (WCL) capable of selectively sequestering pro-inflammatory chemokines is reported. Systematic variation of the local and integral charge densities of the starPEG-GAG hydrogel component allows for tailoring its affinity profile for biomolecular signals of the wound milieu. The composite WCL is subsequently tested in a large animal (porcine) model of human wound healing disorders. Dampening excessive inflammatory signals without affecting the levels of pro-regenerative growth factors, the starPEG-GAG hydrogel-based WCL treatment induced healing with increased granulation tissue formation, angiogenesis, and deposition of connective tissue (collagen fibers). Thus, this biomaterials technology expands the scope of a new anti-inflammatory therapy toward clinical use.
- ItemFibroblast Response to Nanocolumnar TiO2 Structures Grown by Oblique Angle Sputter Deposition(Weinheim : Wiley-VCH, 2021) Kapprell, Uta; Friebe, Sabrina; Grüner, Susann; Grüner, Christoph; Kupferer, Astrid; Rauschenbach, Bernd; Mayr, Stefan G.Cells are established to sense and respond to the properties, including nano- and microscale morphology, of the substrate they adhere to, which opens up the possibility to tailor bioactivity. With this background, the potential of tilted TiO2 nanostructures grown by oblique angle sputtering to affect fibroblasts with particular focus on inducing anisotropy in cell behavior is explored. By depositing TiO2 at different oblique angles relative to the substrate normal, morphologies, columnar tilt angle, roughness, and distances between neighbored nanocolumns can be adjusted. To assess bioactivity of the resulting structures, L929-mouse fibroblasts are seeded in vitro on TiO2 nanostructured substrates. Angle-dependent movement and velocity distributions of the cells on differently tilted columns and a smooth reference sample are studied. Cell proliferation rates and cell areas are additional factors which provide information about viability and the well-being of cells. It could be shown that the local topography of the surface has an influence on the directed movement of the cells. © 2021 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH
- ItemTailoring Intermolecular Interactions Towards High‐Performance Thermoelectric Ionogels at Low Humidity(Weinheim : Wiley-VCH, 2022) Zhao, Wei; Sun, Tingting; Zheng, Yiwei; Zhang, Qihao; Huang, Aibin; Wang, Lianjun; Jiang, WanDevelopment of ionic thermoelectric (iTE) materials is of immense interest for efficient heat-to-electricity conversion due to their giant ionic Seebeck coefficient (Si), but challenges remain in terms of relatively small Si at low humidity, poor stretchability, and ambiguous interaction mechanism in ionogels. Herein, a novel ionogel is reported consisting of polyethylene oxide (PEO), polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and 1-ethyl-3-methylimidazolium acetate (Emim:OAC). By delicately designing the interactions between ions and polymers, the migration of anions is restricted due to their strong binding with the hydroxyl groups of polymers, while the transport of cations is facilitated through segmental motions due to the increased amorphous regions, thereby leading to enlarged diffusion difference between the cations and anions. Moreover, the plasticizing effect of P123 and Emim:OAC can increase the elongation at break. As a consequence, the ionogel exhibits excellent properties including high Si (18 mV K−1 at relative humidity of 60%), good ionic conductivity (1.1 mS cm−1), superior stretchability (787%), and high stability (over 80% retention after 600 h). These findings show a promising strategy to obtain multifunctional iTE materials by engineering the intermolecular interactions and demonstrate the great potential of ionogels for harvesting low-grade heat in human-comfortable humidity environments.
- ItemTransient spin injection efficiencies at ferromagnet/metal interfaces(Weinheim : Wiley-VCH, 2022-10-19) Elliott, Peter; Eschenlohr, Andrea; Chen, Jinghao; Shallcross, Sam; Bovensiepen, Uwe; Dewhurst, John Kay; Sharma, SangeetaSpin injection across interfaces driven by ultrashort optical pulses on femtosecond timescales constitutes a new way to design spintronics applications. Targeted utilization of this phenomenon requires knowledge of the efficiency of non-equilibrium spin injection. From a quantitative comparison of ab initio time-dependent density functional theory and interface-sensitive, time-resolved non-linear optical experiment, the spin injection efficiency (SIE) at the Co/Cu(001) interface is determined, and its microscopic origin, i.e., the influence of spin-orbit coupling and the interface electronic structure, is discussed. Moreover, we theoretically predict that the SIE at ferromagnetic–metal interfaces can be optimized through laser pulse and materials parameters, namely the fluence, pulse duration, and substrate material.
- ItemElectronic Doping and Enhancement of n‐Channel Polycrystalline OFET Performance through Gate Oxide Modifications with Aminosilanes(Weinheim : Wiley-VCH, 2021) Shin, Nara; Schellhammer, Karl Sebastian; Lee, Min Ho; Zessin, Jakob; Hambsch, Mike; Salleo, Alberto; Ortmann, Frank; Mannsfeld, Stefan C.B.Self-assembled monolayers (SAMs) are widely employed in organic field-effect transistors to modify the surface energy, surface roughness, film growth kinetics, and electrical surface potential of the gate oxide to control the device's operating voltage. In this study, amino-functionalized SAM molecules are compared to pure alkylsilane SAMS in terms of their impact on the electrical properties of organic field-effect transistors, using the n-type polycrystalline small molecule semiconductor material N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8). In order to understand the electronic impact of the amino groups, the effect of both the number of amino-containing functional groups and the SAM molecular length are systematically studied. Though amino-functionalized SAM materials have been studied previously, this study is, for the first time, able to shed light on the nature of the doping effect that occurs when the gate oxide is treated with polar aminosilane materials. By a comprehensive theoretical study of the interface on the molecular level, it is shown that the observed shift in the threshold voltage is caused by free charges, which are attracted to the PTCDI-C8 and are stabilized there by protonated aminosilanes. This attraction and the voltage shift can be systematically tuned by varying the length of the neutral terminal chain of the aminosilane. © 2021 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH
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