37 results
Search Results
Now showing 1 - 10 of 37
- ItemApplication of scanning electrochemical microscopy for topography imaging of supported lipid bilayers(Cambridge : RSC Publ., 2022) Nasri, Zahra; Memari, Seyedali; Striesow, Johanna; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Wende, KristianOxidative stress in cellular environments may cause lipid oxidation and membrane degradation. Therefore, studying the degree of lipid membrane morphological changes by reactive oxygen and nitrogen species will be informative in oxidative stress-based therapies. This study introduces the possibility of using scanning electrochemical microscopy as a powerful imaging technique to follow the topographical changes of a solid-supported lipid bilayer model induced by reactive species produced from gas plasma. The introduced strategy is not limited to investigating the effect of reactive species on the lipid bilayer but could be extended to understand the morphological changes of the lipid bilayer due to the action of membrane proteins or antimicrobial peptides.
- ItemBeyond graphene oxide: Laser engineering functionalized graphene for flexible electronics(Cambridge : RSC Publ., 2020) Rodriguez, Raul D.; Khalelov, Alimzhan; Postnikov, Pavel S.; Lipovka, Anna; Dorozhko, Elena; Amin, Ihsan; Murastov, Gennadiy V.; Chen, Jin-Ju; Sheng, Wenbo; Trusova, Marina E.; Chehimi, Mohamed M.; Sheremet, EvgeniyaCarbon nanomaterials, especially graphene, are promising due to their abundance and the possibility to exploit them in lightweight, flexible, and wearable electronics enabling paradigms such as the Internet of Things. However, conventional methods to synthesize and integrate graphene into functional materials and flexible devices are either hazardous, time demanding, or excessively energy-consuming. To overcome these issues, here we propose a new concept based on the laser processing of single-layer diazonium-functionalized graphene. This is a safe, inexpensive, and environmentally-friendly method making it a competitive alternative for graphene-device fabrication. Flexible chemiresistors exhibit sensitivity for breath (water vapor and CO2) and ethanol detection up to 1500% higher than laser-reduced graphene oxide devices. We attribute this enhanced sensitivity to an optimal balance between structural defects and electrical conductivity. Flexible electronic circuits demonstrate a superb resilience against scratching and high current stability up to 98% with durability against 180° bending cycles for continuous operation of several weeks. This work can impact biomedical technology and electronics where tunable electrical conductivity, sensitivity, and mechanical stability are of uttermost importance. © 2020 The Royal Society of Chemistry.
- ItemOptical microresonator arrays of fluorescence-switchable diarylethenes with unreplicable spectral fingerprints(Cambridge : RSC Publ., 2020) Okada, Daichi; Lin, Zhan-Hong; Huang, Jer-Shing; Oki, Osamu; Morimoto, Masakazu; Liu, Xuying; Minari, Takeo; Ishii, Satoshi; Nagao, Tadaaki; Irie, Masahiro; Yamamoto, YoheiHigh-security identification requires authentication that is hard to counterfeit and replicate. For anti-counterfeiting data storage and rewritable memory devices, chromic materials are adoptable, where the dichromatic colours can be switched by external stimuli. If further individual information is embedded in each pixel, a much higher-level security system beyond the zero/one data array will be realized. For this purpose, a fine whispering gallery mode (WGM) fingerprint pattern from a microresonator is applicable. Here we propose that photoswitchable optical microresonators made of a fluorescent photochromic organic material function as anti-counterfeiting, rewritable optical memories. The WGM photoluminescence of the resultant microspheres can be switched on and off repeatedly by irradiation with ultraviolet and visible light. The shape of the microresonator varies from a sphere to an oblate ellipsoid and hemisphere, depending on the self-assembly process, and the WGM spectral pattern depends sensitively on the morphology of the resonators. Furthermore, surface self-assembly on a hydrophobic/hydrophilic micropatterned substrate affords a highly integrated array of microresonators as dense as millions of pixels per square centimetre. The spectral fingerprints of all pixels are different from one another; therefore, the photoswitchable microarrays are applicable as an ultimate anti-counterfeiting system which is hard to replicate. This journal is © 2020 The Royal Society of Chemistry.
- ItemPatterning and control of the nanostructure in plasma thin films with acoustic waves: mechanical vs. electrical polarization effects(Cambridge : RSC Publ., 2021) García-Valenzuela, Aurelio; Fakhfouri, Armaghan; Oliva-Ramírez, Manuel; Rico-Gavira, Victor; Rojas, Teresa Cristina; Alvarez, Rafael; Menzel, Siegfried B.; Palmero, Alberto; Winkler, Andreas; González-Elipe, Agustín R.Nanostructuration and 2D patterning of thin films are common strategies to fabricate biomimetic surfaces and components for microfluidic, microelectronic or photonic applications. This work presents the fundamentals of a surface nanotechnology procedure for laterally tailoring the nanostructure and crystalline structure of thin films that are plasma deposited onto acoustically excited piezoelectric substrates. Using magnetron sputtering as plasma technique and TiO2 as case example, it is demonstrated that the deposited films depict a sub-millimetre 2D pattern that, characterized by large lateral differences in nanostructure, density (up to 50%), thickness, and physical properties between porous and dense zones, reproduces the wave features distribution of the generated acoustic waves (AW). Simulation modelling of the AW propagation and deposition experiments carried out without plasma and under alternative experimental conditions reveal that patterning is not driven by the collision of ad-species with mechanically excited lattice atoms of the substrate, but emerges from their interaction with plasma sheath ions locally accelerated by the AW-induced electrical polarization field developed at the substrate surface and growing film. The possibilities of the AW activation as a general approach for the tailored control of nanostructure, pattern size, and properties of thin films are demonstrated through the systematic variation of deposition conditions and the adjustment of AW operating parameters.
- ItemErratum: Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging (Nanoscale (2021) DOI: 10.1039/D1NR01806J)(Cambridge : RSC Publ., 2021) Carnis, Jerome; Kirner, Felizitas; Lapkin, Dmitry; Sturm, Sebastian; Kim, Young Yong; Baburin, Igor A.; Khubbutdinov, Ruslan; Ignatenko, Alexandr; Iashina, Ekaterina; Mistonov, Alexander; Steegemans, Tristan; Wieck, Thomas; Gemming, Thomas; Lubk, Axel; Lazarev, Sergey; Sprung, Michael; Vartanyants, Ivan A.; Sturm, Elena V.Correction for ‘Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging’ by Jerome Carnis et al., Nanoscale, 2021, DOI: 10.1039/D1NR01806J.
- ItemEther functionalisation, ion conformation and the optimisation of macroscopic properties in ionic liquids(Cambridge : RSC Publ., 2020) Philippi, Frederik; Rauber, Daniel; Kuttich, Björn; Kraus, Tobias; Kay, Christopher W.M.; Hempelmann, Rolf; Hunt, Patricia A.; Welton, TomIonic liquids are an attractive material class due to their wide liquid range, intrinsic ionic conductivity, and high chemical as well as electrochemical stability. However, the widespread use of ionic liquids is hindered by significantly higher viscosities compared to conventional molecular solvents. In this work, we show how the transport properties of ionic liquids can be altered significantly, even for isostructural ions that have the same backbone. To this end, structure–property relationships have been determined for a set of 16 systematically varied representative ionic liquids. Variations in molecular structure include ammonium vs. phosphonium, ether vs. alkyl side chains, and rigid vs. flexible anions. Ab initio calculations are used to relate molecular structures to the thermal, structural and transport properties of the ionic liquids. We find that the differences in properties of ether and alkyl functionalised ionic liquids are primarily dependent on minimum energy geometries, with the conformational flexibility of ether side chains appearing to be of secondary importance. We also show unprecedented correlations between anion conformational flexibility and transport properties. Critically, increasing fluidity upon consecutive introduction of ether side chains and phosphonium centres into the cation is found to be dependent on whether the anion is flexible or rigid. We demonstrate that targeted design of functional groups based on structure–property relationships can yield ionic liquids of exceptionally high fluidity.
- ItemProduction of highly concentrated and hyperpolarized metabolites within seconds in high and low magnetic fields(Cambridge : RSC Publ., 2019) Korchak, Sergey; Emondts, Meike; Mamone, Salvatore; Blümich, Bernhard; Glöggler, StefanHyperpolarized metabolites are very attractive contrast agents for in vivo magnetic resonance imaging studies enabling early diagnosis of cancer, for example. Real-time production of concentrated solutions of metabolites is a desired goal that will enable new applications such as the continuous investigation of metabolic changes. To this end, we are introducing two NMR experiments that allow us to deliver high levels of polarization at high concentrations (50 mM) of an acetate precursor (55% 13C polarization) and acetate (17% 13C polarization) utilizing 83% para-state enriched hydrogen within seconds at high magnetic field (7 T). Furthermore, we have translated these experiments to a portable low-field spectrometer with a permanent magnet operating at 1 T. The presented developments pave the way for a rapid and affordable production of hyperpolarized metabolites that can be implemented in e.g. metabolomics labs and for medical diagnosis.
- ItemNon-touching plasma–liquid interaction – where is aqueous nitric oxide generated?(Cambridge : RSC Publ., 2018) Jablonowski, Helena; Schmidt-Bleker, Ansgar; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Wende, KristianMass transport through graphene is receiving increasing attention due to the potential for molecular sieving. Experimental studies are mostly limited to the translocation of protons, ions, and water molecules, and results for larger molecules through graphene are rare. Here, we perform controlled radical polymerization with surface-anchored self-assembled initiator monolayer in a monomer solution with single-layer graphene separating the initiator from the monomer. We demonstrate that neutral monomers are able to pass through the graphene (via native defects) and increase the graphene defects ratio (Raman ID/IG) from ca. 0.09 to 0.22. The translocations of anionic and cationic monomers through graphene are significantly slower due to chemical interactions of monomers with the graphene defects. Interestingly, if micropatterned initiator-monolayers are used, the translocations of anionic monomers apparently cut the graphene sheet into congruent microscopic structures. The varied interactions between monomers and graphene defects are further investigated by quantum molecular dynamics simulations.
- ItemMagnetically responsive composites: electron beam assisted magnetic nanoparticle arrest in gelatin hydrogels for bioactuation(Cambridge : RSC Publ., 2019) Deuflhard, Marie; Eberbeck, Dietmar; Hietschold, Philine; Wilharm, Nils; Mühlberger, Marina; Friedrich, Ralf P.; Alexiou, Christoph; Mayr, Stefan G.As emerging responsive materials, ferrogels have become highly attractive for biomedical and technical applications in terms of soft actuation, tissue engineering or controlled drug release. In the present study, bioderived ferrogels were fabricated and successfully deformed within moderate, heterogeneous magnetic fields. Synthesis was realized by arresting iron oxide nanoparticles in porcine gelatin by introduction of covalent crosslinks via treatment with energetic electrons for mesh refinement. This approach also allows for tuning thermal and mechanical stability of the gelatin matrix. Operating the bioferrogel in compression, magnetic forces on the nanoparticles are counterbalanced by the stiffness of the hydrogel matrix that is governed by a shift in thermodynamic equilibrium of swelling, as derived in the framework of osmosis. As gelatin and iron oxide nanoparticles are established as biocompatible constituents, these findings promise potential for in vivo use as contactless mechanical transducers.
- ItemPerspectives on weak interactions in complex materials at different length scales(Cambridge : RSC Publ., 2022) Fiedler, J.; Berland, K.; Borchert, J.W.; Corkery, R. W.; Eisfeld, A.; Gelbwaser-Klimovsky, D.; Greve, M.M.; Holst, B.; Jacobs, K.; Krüger, M.; Parsons, D. F.; Persson, C.; Presselt, M.; Reisinger, T.; Scheel, S.; Stienkemeier, F.; Tømterud, M.; Walter, M.; Weitz, R.T.; Zalieckas, J.Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a super-structure, which can be designed to create material properties targeted for specific applications. For electromagnetism, such targeted properties include field enhancements around the bandgap of a semiconductor used for solar cells, directional decay in topological insulators, high kinetic inductance in superconducting circuits, and many more. Despite very different application areas, all of these properties are united by the common aim of exploiting collective interaction effects between quantum objects. The literature on the topic spreads over very many different disciplines and scientific communities. In this review, we present a cross-disciplinary overview of different approaches for the creation, analysis and theoretical description of nanocomposites with applications related to electromagnetic properties.