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- ItemEnlightening Materials with Photoswitches(Weinheim : Wiley-VCH, 2020) Goulet-Hanssens, Alexis; Eisenreich, Fabian; Hecht, StefanIncorporating molecular photoswitches into various materials provides unique opportunities for controlling their properties and functions with high spatiotemporal resolution using remote optical stimuli. The great and largely still untapped potential of these photoresponsive systems has not yet been fully exploited due to the fundamental challenges in harnessing geometrical and electronic changes on the molecular level to modulate macroscopic and bulk material properties. Herein, progress made during the past decade in the field of photoswitchable materials is highlighted. After pointing to some general design principles, materials with an increasing order of the integrated photoswitchable units are discussed, spanning the range from amorphous settings over surfaces/interfaces and supramolecular ensembles, to liquid crystalline and crystalline phases. Finally, some potential future directions are pointed out in the conclusion. In view of the exciting recent achievements in the field, the future emergence and further development of light-driven and optically programmable (inter)active materials and systems are eagerly anticipated. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemMechanochemical activation of disulfide-based multifunctional polymers for theranostic drug release(Cambridge : RSC, 2021) Shi, Zhiyuan; Song, Qingchuan; Göstl, Robert; Herrmann, AndreasDrug delivery systems responsive to physicochemical stimuli allow spatiotemporal control over drug activity to overcome limitations of systemic drug administration. Alongside, the non-invasive real-time tracking of drug release and uptake remains challenging as pharmacophore and reporter function are rarely unified within one molecule. Here, we present an ultrasound-responsive release system based on the mechanochemically induced 5-exo-trigcyclization upon scission of disulfides bearing cargo molecules attachedviaβ-carbonate linker within the center of a water soluble polymer. In this bifunctional theranostic approach, we release one reporter molecule per drug molecule to quantitatively track drug release and distribution within the cell in real-time. We useN-butyl-4-hydroxy-1,8-naphthalimide and umbelliferone as fluorescent reporter molecules to accompany the release of camptothecin and gemcitabine as clinically employed anticancer agents. The generality of this approach paves the way for the theranostic release of a variety of probes and drugs by ultrasound. © The Royal Society of Chemistry 2020.
- ItemSupercharged Proteins and Polypeptides(Weinheim : Wiley-VCH, 2020) Ma, Chao; Malessa, Anke; Boersma, Arnold J.; Liu, Kai; Herrmann, AndreasElectrostatic interactions play a vital role in nature. Biomacromolecules such as proteins are orchestrated by electrostatics, among other intermolecular forces, to assemble and organize biochemistry. Natural proteins with a high net charge exist in a folded state or are unstructured and can be an inspiration for scientists to artificially supercharge other protein entities. Recent findings show that supercharging proteins allows for control of their properties such as temperature resistance and catalytic activity. One elegant method to transfer the favorable properties of supercharged proteins to other proteins is the fabrication of fusions. Genetically engineered, supercharged unstructured polypeptides (SUPs) are just one promising fusion tool. SUPs can also be complexed with artificial entities to yield thermotropic and lyotropic liquid crystals and liquids. These architectures represent novel bulk materials that are sensitive to external stimuli. Interestingly, SUPs undergo fluid–fluid phase separation to form coacervates. These coacervates can even be directly generated in living cells or can be combined with dissipative fiber assemblies that induce life-like features. Supercharged proteins and SUPs are developed into exciting classes of materials. Their synthesis, structures, and properties are summarized. Moreover, potential applications are highlighted and challenges are discussed. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemWet-Spun PEDOT/CNT Composite Hollow Fibers as Flexible Electrodes for H2O2 Production(Weinheim : Wiley-VCH, 2021) Cui, Qing; Bell, Daniel Josef; Wang, Siqi; Mohseni, Mojtaba; Felder, Daniel; Lölsberg, Jonas; Wessling, MatthiasThe electrochemical synthesis of hydrogen peroxide (H2O2) using the oxygen reduction reaction (ORR) requires highly catalytic active, selective, and stable electrode materials to realize a green and efficient process. The present publication shows for the first time the application of a facile one-step bottom-up wet-spinning approach for the continuous fabrication of stable and flexible tubular poly(3,4-ethylene dioxythiophene) (PEDOT : PSS) and PEDOT : PSS/carbon nanotube (CNT) hollow fibers. Additionally, electrochemical experiments reveal the catalytic activity of acid-treated PEDOT : PSS and its composites in the ORR forming hydrogen peroxide for the first time. Under optimized conditions, the composite electrodes with 40 wt % CNT loading could achieve a high production rate of 0.01 mg/min/cm2 and a current efficiency of up to 54 %. In addition to the high production rate, the composite hollow fiber has proven its long-term stability with 95 % current retention after 20 h of hydrogen peroxide production. © 2021 The Authors. ChemElectroChem published by Wiley-VCH GmbH
- ItemEffects of proline substitutions on the thermostable LOV domain from Chloroflexus aggregans(Basel : MDPI AG, 2020) Remeeva, Alina; Nazarenko, Vera V.; Goncharov, Ivan M.; Yudenko, Anna; Smolentseva, Anastasia; Semenov, Oleg; Kovalev, Kirill; Gülbahar, Cansu; Schwaneberg, Ulrich; Davari, Mehdi D.; Gordeliy, Valentin; Gushchin, IvanLight-oxygen-voltage (LOV) domains are ubiquitous photosensory modules found in proteins from bacteria, archaea and eukaryotes. Engineered versions of LOV domains have found widespread use in fluorescence microscopy and optogenetics, with improved versions being continuously developed. Many of the engineering efforts focused on the thermal stabilization of LOV domains. Recently, we described a naturally thermostable LOV domain from Chloroflexus aggregans. Here we show that the discovered protein can be further stabilized using proline substitution. We tested the effects of three mutations, and found that the melting temperature of the A95P mutant is raised by approximately 2◦ C, whereas mutations A56P and A58P are neutral. To further evaluate the effects of mutations, we crystallized the variants A56P and A95P, while the variant A58P did not crystallize. The obtained crystal structures do not reveal any alterations in the proteins other than the introduced mutations. Molecular dynamics simulations showed that mutation A58P alters the structure of the respective loop (Aβ-Bβ), but does not change the general structure of the protein. We conclude that proline substitution is a viable strategy for the stabilization of the Chloroflexus aggregans LOV domain. Since the sequences and structures of the LOV domains are overall well-conserved, the effects of the reported mutations may be transferable to other proteins belonging to this family. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- ItemDigitally Fabricated and Naturally Augmented In Vitro Tissues(Weinheim : Wiley-VCH, 2020) Duarte Campos, Daniela F.; De Laporte, LauraHuman in vitro tissues are extracorporeal 3D cultures of human cells embedded in biomaterials, commonly hydrogels, which recapitulate the heterogeneous, multiscale, and architectural environment of the human body. Contemporary strategies used in 3D tissue and organ engineering integrate the use of automated digital manufacturing methods, such as 3D printing, bioprinting, and biofabrication. Human tissues and organs, and their intra- and interphysiological interplay, are particularly intricate. For this reason, attentiveness is rising to intersect materials science, medicine, and biology with arts and informatics. This report presents advances in computational modeling of bioink polymerization and its compatibility with bioprinting, the use of digital design and fabrication in the development of fluidic culture devices, and the employment of generative algorithms for modeling the natural and biological augmentation of in vitro tissues. As a future direction, the use of serially linked in vitro tissues as human body-mimicking systems and their application in drug pharmacokinetics and metabolism, disease modeling, and diagnostics are discussed. © 2020 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH
- ItemComputer-Assisted Recombination (CompassR) Teaches us How to Recombine Beneficial Substitutions from Directed Evolution Campaigns(Weinheim : Wiley-VCH, 2020) Cui, Haiyang; Cao, Hao; Cai, Haiying; Jaeger, Karl-Erich; Davari, Mehdi D.; Schwaneberg, UlrichA main remaining challenge in protein engineering is how to recombine beneficial substitutions. Systematic recombination studies show that poorly performing variants are usually obtained after recombination of 3 to 4 beneficial substitutions. This limits researchers in exploiting nature's potential in generating better enzymes. The Computer-assisted Recombination (CompassR) strategy provides a selection guide for beneficial substitutions that can be recombined to gradually improve enzyme performance by analysis of the relative free energy of folding (ΔΔGfold). The performance of CompassR was evaluated by analysis of 84 recombinants located on 13 positions of Bacillus subtilis lipase A. The finally obtained variant F17S/V54K/D64N/D91E had a 2.7-fold improved specific activity in 18.3 % (v/v) 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). In essence, the deducted CompassR rule allows recombination of beneficial substitutions in an iterative manner and empowers researchers to generate better enzymes in a time-efficient manner. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
- ItemSolvent effects on catalytic activity and selectivity in amine-catalyzed D-fructose isomerization(Amsterdam [u.a.] : Elsevier, 2022) Drabo, Peter; Fischer, Matthias; Emondts, Meike; Hamm, Jegor; Engelke, Mats; Simonis, Marc; Qi, Long; Scott, Susannah L.; Palkovits, Regina; Delidovich, IrinaRational catalyst design and optimal solvent selection are key to advancing biorefining. Here, we explored the organocatalytic isomerization of D-fructose to a valuable rare monosaccharide, D-allulose, as a function of solvent. The isomerization of D-fructose to D-allulose competes with its isomerization to D-glucose and sugar degradation. In both water and DMF, the catalytic activity of amines towards D-fructose is correlated with their basicity. Solvents impact the selectivity significantly by altering the tautomeric distribution of D-fructose. Our results suggest that the furanose tautomer of D-fructose is isomerized to D-allulose, and the fractional abundance of this tautomer increases as follows: water < MeOH < DMF ≈ DMSO. Reaction rates are also higher in aprotic than in protic solvents. The best D-allulose yield, 14 %, was obtained in DMF with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst. The reaction kinetics and mechanism were explored using operando NMR spectroscopy.
- ItemTubular hollow fibre electrodes for CO2 reduction made from copper aluminum alloy with drastically increased intrinsic porosity(Amsterdam [u.a.] : Elsevier Science, 2020) Bell, Daniel; Rall, Deniz; Großeheide, Maren; Marx, Lennart; Hülsdünker, Laura; Wessling, MatthiasElectrochemical reduction of CO2 to higher-order hydrocarbon products offers a significant contribution to the challenge of a circular economy. In the pursuit of better copper metal catalyst, it was early on realized that increasing productivity of copper catalysts systems is reliant on high surface area per volume. Tubular gas diffusion electrodes offer such properties. In this work, we present a methodology to fabricate tubular hollow fibre copper electrodes with drastically increased intrinsic porosity. Our described method utilizes a standard dealloying process of copper aluminium particles to induce an intra-particle nanoporosity. The specific surface area increases from 0.126 m2 g−1 before dealloying to 6.194 m2 g−1 after dealloying. In comparison to conventional planar copper electrodes and literature data from conventional copper hollow fibres, the intra-particle porosity leads to a drastically increase in electrochemical activity. Electrochemical measurements reveal increased current densities at low over-potentials in comparison to conventional copper electrodes under identical experimental conditions emphasizing the significant impact of the porosity on the electrode performance. The presented method can be easily transferred to other alloy particles, highlighting its versatility for electrode fabrication. © 2019 The Author(s)
- ItemHigh Throughput Centrifugal Electrospinning of Polyacrylonitrile Nanofibers for Carbon Fiber Nonwovens(Basel : MDPI, 2021) Hoffmann, Andreas; Kuehne, Alexander J. C.Carbon nanofiber nonwovens are promising materials for electrode or filtration applications; however, their utilization is obviated by a lack of high throughput production methods. In this study, we utilize a highly effective high-throughput method for the fabrication of polyacrylonitrile (PAN) nanofibers as a nonwoven on a dedicated substrate. The method employs rotational-, air pressure- and electrostatic forces to produce fibers from the inner edge of a rotating bell towards a flat collector. We investigate the impact of all above-mentioned forces on the fiber diameter, morphology, and bundling of the carbon-precursor PAN fibers. The interplay of radial forces with collector-facing forces has an influence on the uniformity of fiber deposition. Finally, the obtained PAN nanofibers are converted to carbon nonwovens by thermal treatment.