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- ItemPhysical gels of poly(vinylamine) by thermal curing(Cambridge : Royal Society of Chemistry, 2020) Fischer, Thorsten; Köhler, Jens; Möller, Martin; Singh, SmritiPhysical gels are a versatile class of materials which can find application in sensors, electrochemistry, biomedicine or rheological modifiers. Herein, we present a hydrogen-bonded physical gel which is based on the interaction between phenylcarbonate telechelic poly(ethylene glycol) (PEG-PC) and poly(vinyl amine-co-acetamide) (p(VAm-co-VAA)). The critical gelation concentration was found to be 10 wt% by rheology and NMR. UV-vis spectroscopy and dynamic light scattering reveal the formation of aggregates in the gel. Rheology and differential scanning calorimetry (DSC) was used to show the effect of thermal curing on the mechanical properties of the physical gel. © The Royal Society of Chemistry 2020.
- ItemA New Approach to Harness Probiotics Against Common Bacterial Skin Pathogens: Towards Living Antimicrobials(New York, NY [u.a.] : Springer, 2021) Khalfallah, Ghazi; Gartzen, Rita; Möller, Martin; Heine, Elisabeth; Lütticken, RudolfIn this study, the potential of certain lactic acid bacteria—classified as probiotics and known to be antimicrobially active against pathogens or food-poisoning microorganisms—was evaluated with respect to their activity against bacterial skin pathogens. The aim of the study was to develop a plaster/bandage for the application of inhibitory substances produced by these probiotics when applied to diseased skin. For this purpose, two Streptococcus salivarius strains and one Lactobacillus plantarum were tested for production of antimicrobials (bacteriocin-like substances) active against Gram-positive and Gram-negative pathogens using established methods. A newly designed membrane test ensured that the probiotics produce antimicrobials diffusible through membranes. Target organisms used were Cutibacterium acnes, Staphylococcus aureus, and Pseudomonas aeruginosa. Moreover, the L. plantarum 8P-A3 strain was tested against additional bacteria involved in skin disorders. The Lactobacillales used were active against all potential skin pathogens tested. These probiotics could be enclosed between polymer membranes—one tight, the other permeable for their products, preserved by vacuum drying, and reactivated after at least three months storage. Importantly, the reactivated pads containing the probiotics demonstrated antibacterial activity on agar plates against all pathogens tested. This suggests that the probiotic containing pads may be topically applied for the treatment of skin disorders without the need for a regular antibiotic treatment or as an adjunctive therapy.
- ItemMicrogel that swims to the beat of light(Berlin ; Heidelberg : Springer, 2021) Mourran, Ahmed; Jung, Oliver; Vinokur, Rostislav; Möller, MartinComplementary to the quickly advancing understanding of the swimming of microorganisms, we demonstrate rather simple design principles for systems that can mimic swimming by body shape deformation. For this purpose, we developed a microswimmer that could be actuated and controlled by fast temperature changes through pulsed infrared light irradiation. The construction of the microswimmer has the following features: (i) it is a bilayer ribbon with a length of 80 or 120 μm, consisting of a thermo-responsive hydrogel of poly-N-isopropylamide coated with a 2-nm layer of gold and equipped with homogeneously dispersed gold nanorods; (ii) the width of the ribbon is linearly tapered with a wider end of 5 μm and a tip of 0.5 μm; (iii) a thickness of only 1 and 2 μm that ensures a maximum variation of the cross section of the ribbon along its length from square to rectangular. These wedge-shaped ribbons form conical helices when the hydrogel is swollen in cold water and extend to a filament-like object when the temperature is raised above the volume phase transition of the hydrogel at 32∘C. The two ends of these ribbons undergo different but coupled modes of motion upon fast temperature cycling through plasmonic heating of the gel-objects from inside. Proper choice of the IR-light pulse sequence caused the ribbons to move at a rate of 6 body length/s (500 μm/s) with the wider end ahead. Within the confinement of rectangular container of 30 μm height and 300 μm width, the different modes can be actuated in a way that the movement is directed by the energy input between spinning on the spot and fast forward locomotion.
- ItemFormaldehyde-free curing of cotton cellulose fabrics in anhydrous media(New York, NY : Wiley, 2020) Mommer, Stefan; Kurniadi, Juliana; Keul, Helmut; Möller, MartinThe effect of formaldehyde-free curing on standard cotton cellulose fabrics in anhydrous media is studied. Different crosslinkers are applied via (1) a pad-cure-dry process (solid/liquid) and (2) in a vapor chamber (solid/gas). The performance of each crosslinker and set of conditions is assessed by measuring dry crease recovery angles, DCRAs. We find that in control samples (treatment without crosslinker) the DCRAs are altered depending on the solvent. Using DMF, carbonyldiimidazole shows the best DCRA (160.1°, 15° higher than the non-treated fabrics). In ethyl acetate, triglycidyl isocyanurate shows the highest DCRA (22° higher than the control). The most promising crosslinkers are applied with selected catalysts known from literature. Here, trigycidyl isocyanurate in combination with the superbase P4-t-Bu gives the best DCRA (35° higher than the control). Using the vapor-chemical finishing, divinylsulfone as crosslinker increases the DCRA to 162.7° (18° higher than non-treated fabrics). Hence, cotton cellulose fabrics can be successfully finished in anhydrous conditions. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48371. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc.
- ItemNanovesicles displaying functional linear and branched oligomannose self-assembled from sequence-defined Janus glycodendrimers(Washington, DC : NAS, 2020) Xiao, Qi; Delbianco, Martina; Sherman, Samuel E.; Reveron Perez, Aracelee M.; Bharate, Priya; Pardo-Vargas, Alonso; Rodriguez-Emmenegger, Cesar; Kostina, Nina Yu; Rahimi, Khosrow; Söder, Dominik; Möller, Martin; Klein, Michael L.; Seeberger, Peter H.; Percec, VirgilCell surfaces are often decorated with glycoconjugates that contain linear and more complex symmetrically and asymmetrically branched carbohydrates essential for cellular recognition and communication processes. Mannose is one of the fundamental building blocks of glycans in many biological membranes. Moreover, oligomannoses are commonly found on the surface of pathogens such as bacteria and viruses as both glycolipids and glycoproteins. However, their mechanism of action is not well understood, even though this is of great potential interest for translational medicine. Sequence-defined amphiphilic Janus glycodendrimers containing simple mono- and disaccharides that mimic glycolipids are known to self-assemble into glycodendrimersomes, which in turn resemble the surface of a cell by encoding carbohydrate activity via supramolecular multivalency. The synthetic challenge of preparing Janus glycodendrimers containing more complex linear and branched glycans has so far prevented access to more realistic cell mimics. However, the present work reports the use of an isothiocyanate-amine “click”-like reaction between isothiocyanate-containing sequence-defined amphiphilic Janus dendrimers and either linear or branched oligosaccharides containing up to six monosaccharide units attached to a hydrophobic amino-pentyl linker, a construct not expected to assemble into glycodendrimersomes. Unexpectedly, these oligoMan-containing dendrimers, which have their hydrophobic linker connected via a thiourea group to the amphiphilic part of Janus glycodendrimers, self-organize into nanoscale glycodendrimersomes. Specifically, the mannose-binding lectins that best agglutinate glycodendrimersomes are those displaying hexamannose. Lamellar “raft-like” nanomorphologies on the surface of glycodendrimersomes, self-organized from these sequence-defined glycans, endow these membrane mimics with high biological activity. © 2020 National Academy of Sciences. All rights reserved.
- ItemReconstruction of Ultra-thin Alveolar-capillary Basement Membrane Mimics(Weinheim : Wiley-VCH, 2021) Jain, Puja; Nishiguchi, Akihiro; Linz, Georg; Wessling, Matthias; Ludwig, Andreas; Rossaint, Rolf; Möller, Martin; Singh, SmritiAlveolar-capillary basement membrane (BM) is ultra-thin (<2 µm) extracellular matrix that maintains integral epithelial-endothelial cell layers. In vitro reconstructions of alveolar-capillary barrier supported on synthetic scaffolds closely resembling the fibrous and ultra-thin natural BM are essential in mimicking the lung pathophysiology. Although BM topology and dimensions are well known to significantly influence cellular behavior, conventionally used BM mimics fail to recreate this natural niche. To overcome this, electrospun ultra-thin 2 µm poly(caprolactone) (PCL) nanofibrous mesh is used to establish an alveolar-capillary barrier model of lung endothelial/epithelial cells. Transepithelial electrical resistance (TEER) and permeability studies reveal integral tight junctions and improved mass transport through the highly porous PCL meshes compared to conventional dense membranes with etched pores. The chemotaxis of neutrophils is shown across the barrier in presence of inflammatory response that is naturally impeded in confined regions. Conventional requirement of 3 µm or larger pore size can lead to barrier disruption due to epithelial/endothelial cell invasion. Despite high porosity, the interconnected BM mimic prevents barrier disruption and allows neutrophil transmigration, thereby demonstrating the physiological relevance of the thin nanofibrous meshes. It is envisioned that these bipolar cultured barriers would contribute to an organ-level in vitro model for pathological disease, environmental pollutants, and nanotoxicology. © 2021 The Authors. Advanced Biology published by Wiley-VCH GmbH
- ItemTrypsin-Free Cultivation of 3D Mini-Tissues in an Adaptive Membrane Bioreactor(Weinheim : Wiley-VCH, 2020) Djeljadini, Suzana; Lohaus, Theresa; Gausmann, Marcel; Rauer, Sebastian; Kather, Michael; Krause, Bernd; Pich, Andrij; Möller, Martin; Wessling, MatthiasThe production of large scaffold-free tissues is a key challenge in regenerative medicine. Nowadays, temperature-responsive polymers allow intact tissue harvesting without needing proteolytic enzymes. This method is limited to tissue culture plastic with limited upscaling capacity and plain process control. Here, a thermoresponsive hollow fiber membrane bioreactor is presented to produce large scaffold-free tissues. Intact tissues, rich in cell-to-cell connections and ECM, are harvested from a poly(N-vinylcaprolactam) microgel functionalized poly(ether sulfone)/poly(vinylpyrrolidone) hollow fiber membrane by a temperature shift. The harvested 3D tissues adhere in successive cultivation and exhibit high vitality for several days. The facile adsorptive coating waives the need for extensive surface treatment. The research is anticipated to be a starting point for upscaling the production of interconnected tissues enabling new opportunities in regenerative medicine, large-scale drug screening on physiological relevant tissues, and potentially opening new chances in cell-based therapies. © 2020 The Authors. Advanced Biosystems published by Wiley-VCH GmbH
- Item4D Printing of a Light-Driven Soft Actuator with Programmed Printing Density(Washington, DC : ACS Publications, 2020) Nishiguchi, Akihiro; Zhang, Hang; Schweizerhof, Sjören; Schulte, Marie Friederike; Mourran, Ahmed; Möller, MartinThere is a growing interest in the concept of four-dimensional (4D) printing that combines a three-dimensional (3D) manufacturing process with dynamic modulation for bioinspired soft materials exhibiting more complex functionality. However, conventional approaches have drawbacks of low resolution, control of internal micro/nanostructure, and creation of fast, complex actuation due to a lack of high-resolution fabrication technology and suitable photoresist for soft materials. Here, we report an approach of 4D printing that develops a bioinspired soft actuator with a defined 3D geometry and programmed printing density. Multiphoton lithography (MPL) allows for controlling printing density in gels at pixel-by-pixel with a resolution of a few hundreds of nanometers, which tune swelling behaviors of gels in response to external stimuli. We printed a 3D soft actuator composed of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) and gold nanorods (AuNRs). To improve the resolution of printing, we synthesized a functional, thermoresponsive macrocrosslinker. Through plasmonic heating by AuNRs, nanocomposite-based soft actuators undergo nonequilibrium, programmed, and fast actuation. Light-mediated manufacture and manipulation (MPL and photothermal effect) offer the feasibility of 4D printing toward adaptive bioinspired soft materials. Copyright © 2020 American Chemical Society.