INMdok (Leibniz Institute for New Materials)
Not a member yet
931 research outputs found
Sort by
Annual report 2021 / Leibniz Institute for New Materials
Get PDFVorwort: Das Institut hat trotz der notwendigen Einschränkungen wieder ein erfolgreiches Jahr hinter sich. Unter anderem gab es folgende organisatorische Neuerungen: Gefördert durch einen ERC Starting Grant hat die neue Juniorforschungsgruppe Elektrofluide unter der Leitung von Frau Dr. Lola Gonzalez-Garcia ihre Arbeit aufgenommen. Der vormalige Programmbereich Nanotribologie unter der Leitung von Herrn Prof. Roland Bennewitz hat seinen Namen geändert. Die Weiterentwicklung der thematischen Schwerpunkte des Programmbereichs gaben Anlass für eine Anpassung auf den Namen Interaktive Oberflächen.
Auch der vom INM koordinierte Leibniz-Forschungsverbund Nanosicherheit hat sein Themenspektrum weiterentwickelt. In seine zweite Laufzeit geht er unter dem Namen Leibniz-Forschungsverbund Advanced Materials Safety. 2021 brachte dem INM gleich zwei neue Fellows: Das INM hat den Materialwissenschaftler Prof. Martin Müser und den theoretischen Physiker Prof. Heiko Rieger, beide von der Universität des Saarlandes, zu INM-Fellows ernannt. Prof. Müsers Fokus liegt in Simulationen zur Optimierung von Haftstrukturen, Prof. Rieger untersucht Prozesse in biologischen Systemen. Weitere Weichen für die Zukunft werden gestellt: Von besonderer Bedeutung ist dabei das Berufungsverfahren für die Nachfolge von Herrn Prof. Eduard Arzt als wissenschaftlichem Geschäftsführer. Aber auch die Baumaßnahmen im Zuge der Renovierung des Bauteils B, den das INM von der Unversität des Saarlandes übernimmt, spielen eine wichtige Rolle für die Zukunft des Instituts.
Wir danken unseren Mitarbeiterinnen und Mitarbeitern für das Verständnis, die Disziplin und die Resilienz in schweren Zeiten und freuen uns, wenn Sie uns auch in Zukunft gewogen bleiben
Bioinspired microstructured adhesives for medical applications
Get PDFAdhesives for interaction with human skin and tissues are needed for multiple applications, from wearable electronics to medical devices for diagnostics and therapy. Bioinspired fibrillar structures, initially developed for robotics, were upgraded for adhesion to biological surfaces to solve problems in medicine. Using a fibrillar array topped by a soft skin adhesive (SSA) layer, the film-terminated design exhibits effective adhesion to skin-like rough surfaces compared to unstructured samples. The glue-free, reliable adhesion to skin opens a large spectrum of possibilities for applications in biomedicine. Moreover, we investigated the adhesion of the microstructure to explanted mouse eardrums for application as wound dressing for eardrum perforations. The subsurface microstructure was also found to dampen any impact, protecting the sensitive membrane during application. Animal tests showed promising results to replace current surgical approaches with a less invasive and more effective treatment with microstructured adhesives.Adhäsive für die Interaktion mit menschlicher Haut und menschlichem Gewebe werden für zahlreiche Anwendungen, von Wearables bis zu medizinischen Geräten für Diagnostik und Therapie, benötigt. Bioinspirierte fibrilläre Mikrostrukturen, die ursprünglich für die Robotik entwickelt wurden, wurden hier für die Haftung an biologischen Oberflächen weiterentwickelt, um innovative Anwendungen in der Medizin zu bieten. Unter Verwendung eines fibrillären Arrays, das mit einer Schicht aus einem weichem Polymer (SSA) bedeckt ist, zeigt das filmterminierte Design, im Vergleich zu unstrukturierten Proben, eine effektive Haftung auf hautähnlichen rauen Oberflächen. Die klebstofffreie, zuverlässige Haftung auf der Haut eröffnet ein breites Spektrum an Verwendungsmöglichkeiten in der Biomedizin. Darüber hinaus untersuchten wir die Haftung der Mikrostruktur an explantierten Maus-Trommelfellen zur Anwendung als Verschlussmaterial bei Trommelfellperforationen. Es wurde auch festgestellt, dass die Mikrostruktur unter der Deckschicht zusätzlichen Druck dämpft und die empfindliche Membran während der Applikation schützt. Tierversuche zeigten vielversprechende Ergebnisse zum Ersatz aktueller chirurgischer Eingriffe durch eine weniger invasive und effektivere Behandlung mit mikrostrukturierten Pflastern
Monitoring bioinspired fibrillar grippers by contact observation and machine learning
Get PDFThe remarkable properties of bio-inspired microstructures make them extensively accessible for various applications, including industrial, medical, and space applications. However, their implementation especially as grippers for pick-and-place robotics can be compromised by multiple factors. The most common ones are alignment imperfections with the target object, unbalanced stress distribution, contamination, defects, and roughness at the gripping interface. In the present work, three different approaches to assess the contact phenomena between patterned structures and the target object are presented. First, in-situ observation and machine learning are combined to realize accurate real-time predictions of adhesion performance. The trained supervised learning models successfully predict the adhesion performance from the contact signature. Second, two newly developed optical systems are compared to observe the correct grasping of various target objects (rough or transparent) by looking through the microstructures. And last, model experiments are provided for a direct comparison with simulation efforts aiming at a prediction of the contact signature and an analysis of the rate and preload-dependency of the adhesion strength of a soft polymer film in contact with roughness-like surface topography. The results of this thesis open new perspectives for improving the reliability of handling systems using bioinspired microstructures.Durch die besonderen Eigenschaften bioinspirierter Mikrostrukturen können diese für verschiedene Anwendungen genutzt werden, einschließlich industrieller, medizinischer und Weltraumanwendungen. Ihre Implementierung, insbesondere als Greifer für Pick-and-Place-Robotiker, kann jedoch durch mehrere Faktoren beeinträchtigt werden. Am häufigsten sind Ausrichtungsmängel an das Zielobjekt, unausgeglichene Spannungsverteilungen, Defekte und Rauheit an der Greifschnittstelle. Die vorliegende Arbeit zeigt drei verschiedene Ansätze, um den Kontakt zwischen strukturierten Adhäsiven und Zielobjekten zu untersuchen. Zunächst werden in-situ Beobachtungen und maschinelles Lernen kombiniert, um Echtzeitvorhersagen der Adhäsionsleistung zu ermöglichen. Die trainierten Modelle werden verwendet, um die Haftungsleistung anhand der Kontaktsignatur des Pads erfolgreich zu prognostizieren. Anschließend werden zwei neu entwickelte, optische Systeme verglichen, mit denen das korrekte ” Greifen“ von verschiedenen Objekten (mit rauen oder undurchsichtigen Oberflächen) durch die Mikrostrukturen live verfolgt werden kann. Zuletzt werden Modellexperimente durchgeführt, die mit Simulationen der Signatur des Kontakts einer weichen Polymerschicht mit einer idealisierten rauen Gegenfläche direkt verglichen werden können. Die Ergebnisse dieser Arbeit eröffnen neue Perspektiven zur zuverlässigeren Verwendung von Handhabungssystemen mit bioinspirierten Mikrostrukturen
Regulating bacterial behavior within hydrogels of tunable viscoelasticity
Get PDFEngineered living materials (ELMs) are a new class of materials in which living organism incorporated into diffusive matrices uptake a fundamental role in material’s composition and function. Understanding how the spatial confinement in 3D affects the behavior of the embedded cells is crucial to design and predict ELM’s function, regulate and minimize their environmental impact and facilitate their translation into applied materials. This study investigates the growth and metabolic activity of bacteria within an associative hydrogel network (Pluronic-based) with mechanical properties that can be tuned by introducing a variable degree of acrylate crosslinks. Individual bacteria distributed in the hydrogel matrix at low density form functional colonies whose size is controlled by the extent of permanent crosslinks. With increasing stiffness and decreasing plasticity of the matrix, a decrease in colony volumes and an increase in their sphericity is observed. Protein production surprisingly follows a different pattern with higher production yields occurring in networks with intermediate permanent crosslinking degrees. These results demonstrate that, bacterial mechanosensitivity can be used to control and regulate the composition and function of ELMs by thoughtful design of the encapsulating matrix, and by following design criteria with interesting similarities to those developed for 3D culture of mammalian cells
Design of high-performance antimony/MXene hybrid electrodes for sodium-ion batteries
Get PDFDue to their versatile properties and excellent electrical conductivity, MXenes have become attractive materials for alkali metal-ion batteries. However, as the capacity is limited to lower values due to the intercalation mechanism, these materials can hardly keep up in the ever-fast-growing community of battery research. Antimony has a promisingly high theoretical sodiation capacity characterized by an alloying reaction. The main drawback of this type of battery material is related to the high volume changes during cycling, often leading to electrode cracking and pulverization, resulting in poor electrochemical performance. A synergistic effect of combing antimony and MXene can be expected to obtain an optimized electrochemical system to overcome capacity fading of antimony while taking advantage of MXene charge storage ability. In this work, variation of the synthesis parameters and material design strategy have been dedicated to achieving the optimized antimony/MXene hybrid electrodes for high-performance sodium-ion batteries. The optimized performance does not align with the highest amount of antimony, the smallest nanoparticles, or the largest interlayer distance of MXene but with the most homogeneous distribution of antimony and MXene while both components remain electrochemically addressable. As a result, the electrode with 40 mass% MXene, not previously expanded, etched with 5 mass% HF and 60% antimony synthesized on the surfaces of MXene emerged as the best electrode. We obtained a high reversible capacity of 450 mA h g−1 at 0.1 A g−1 with a capacity retention of around 96% after 100 cycles with this hybrid material. Besides the successful cycling stability, this material also exhibits high rate capability with a capacity of 365 mA h g−1 at 4 A g−1. In situ XRD measurements and post mortem analysis were used to investigate the reaction mechanism
Nano-in-Microparticles for Aerosol Delivery of Antibiotic-Loaded, Fucose-Derivatized, and Macrophage-Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery
Get PDFNontuberculous mycobacterial infections rapidly emerge and demand potent medications to cope with resistance. In this context, targeted loco-regional delivery of aerosol medicines to the lungs is an advantage. However, sufficient antibiotic delivery requires engineered aerosols for optimized deposition. Here, the effect of bedaquiline-encapsulating fucosylated versus nonfucosylated liposomes on cellular uptake and delivery is investigated. Notably, this comparison includes critical parameters for pulmonary delivery, i.e., aerosol deposition and the noncellular barriers of pulmonary surfactant (PS) and mucus. Targeting increases liposomal uptake into THP-1 cells as well as peripheral blood monocyte- and lung-tissue derived macrophages. Aerosol deposition in the presence of PS, however, masks the effect of active targeting. PS alters antibiotic release that depends on the drug's hydrophobicity, while mucus reduces the mobility of nontargeted more than fucosylated liposomes. Dry-powder microparticles of spray-dried bedaquiline-loaded liposomes display a high fine particle fraction of >70%, as well as preserved liposomal integrity and targeting function. The antibiotic effect is maintained when deposited as powder aerosol on cultured Mycobacterium abscessus. When treating M. abscessus infected THP-1 cells, the fucosylated variant enabled enhanced bacterial killing, thus opening up a clear perspective for the improved treatment of nontuberculous mycobacterial infections
Synthesis of 3,4-Dihydro-2H-pyrroles from Ketones, Aldehydes, and Nitro Alkanes via Hydrogenative Cyclization
Get PDFSyntheses of N-heterocyclic compounds that permit a flexible introduction of various substitution patterns using inexpensive and diversely available starting materials are highly desirable. Easy to handle and reusable catalysts based on earth-abundant metals are especially attractive for these syntheses. We report here on the synthesis of 3,4-dihydro-2H-pyrroles via the hydrogenation and cyclization of nitro ketones. The latter are easily accessible from three components: a ketone, an aldehyde and a nitroalkane. Our reaction has a broad scope and 23 of the 33 products synthesized are compounds which have not yet been reported. The key to the general hydrogenation/cyclization reaction is a highly active, selective and reusable nickel catalyst, which was identified from a library of 24 earth-abundant metal catalysts
Endothelial cell spreading on lipid bilayers with combined integrin and cadherin binding ligands
Get PDFEndothelial cells play a central role in the vascular system, where their function is tightly regulated by both cell-extracellular matrix (e.g., via integrins) and cell–cell interactions (e.g., via cadherins). In this study, we incorporated cholesterol-modified integrin and N-cadherin peptide binding ligands in fluid supported lipid bilayers. Human umbilical vein endothelial cell adhesion, spreading and vinculin localization in these cells were dependent on ligand density. One composition led to observe a higher extent of cell spreading, where cells exhibited extensive lamellipodia formation and a qualitatively more distinct N-cadherin localization at the cell periphery, which is indicative of N-cadherin clustering and a mimic of cell–cell contact formation. The results can be used to reconstitute the endothelial-pericyte interface on biomedical devices and materials
Shape stability and bundling of ultrathin nanowires
Get PDFUltrathin nanowires are promising nanoscale materials. They can reach length-to-diameter aspect ratios exceeding 1000, making them suitable building blocks for optoelectronic devices such as transparent conducting films. An organic ligand shell surrounds their inorganic core, provides colloidal stability, and guides their one-dimensional growth. Two unresolved issues limit their application. Nanowires can agglomerate into elongated bundles, but efficient use of this superstructure is difficult since we do not yet understand the bundling mechanisms. Furthermore, nanowires are prone to the Plateau-Rayleigh instability: thin wires tend to fragment into discrete spheroidal particles to reduce their surface energy, limiting their lifetime and reliability. This thesis investigates superstructure formation and nanowire stability and the link between both topics. Bundles are shown to emerge in non-polar solvents for entropic reasons. Solvent or unbound ligand molecules align in proximity to the ligand shell, thus losing entropy. Bundling decreases this loss in entropy by reducing contact with the bulk solvent. The structural stability of nanowires is enhanced or degraded by the ligand shell, depending on the relationship between free energy and local surface curvature. Kinetic barriers in ad- and desorbing ligands and rearrangement of surface atoms slow down the break-up. Bundling further stabilizes the wires by confining the space available to them.Ultradünne Nanodrähte, bestehend aus einem anorganischen Kern und einer organischen Ligandenhülle, können Aspektverhältnisse von über 1:1000 erreichen und sind potenzielle Materialien für optoelektronische Technologien wie transparente Elektroden. Einer breiteren Anwendung stehen zwei Herausforderungen entgegen. Nanodrähte können zu Bündeln agglomerieren, aber eine effiziente Nutzung dieser Superstruktur ist schwierig, da unser Verständnis der zugrundeliegenden Bündelungsmechanismen unvollständig ist. Zudem sind Nanodrähte instabil: gemäß der Plateau-Rayleigh-Instabilität zerbrechen sie zur Reduktion ihrer Oberflächenenergie in kleinere Nanopartikel, was ihre Langzeit-Anwendung verhindert. Sowohl Formstabilität und Superstruktur als auch der Zusammenhang zwischen beiden Themen wurden in dieser Dissertation untersucht. Bündel entstehen in unpolaren Lösemitteln, weil sich Lösemittelmoleküle oder freie Liganden parallel zur Ligandenhülle ausrichten und dabei Entropie verlieren. Durch die Anordnung in Bündeln wird der Kontakt zum Lösemittel reduziert, sodass der Entropieverlust geringer ausfällt. Die Formstabilität von Nanodrähten wird von der Ligandenhülle verbessert oder verschlechtert, je nach Zusammenhang zwischen freier Energie und Oberflächenkrümmung. Kinetische Barrieren in der Ad- und Desorption von Liganden und der Reorganisation der Oberfläche verlangsamen den Zerfall. Bündel verbessern die Formstabilität, indem sie den für die Nanodrähte verfügbaren Raum begrenzen
Interacting particles in an activity landscape
No full textWe study interacting active Brownian particles (ABPs) with a space-dependent swim velocity via simulation and theory. We find that, although an equation of state exists, a mechanical equilibrium does not apply to ABPs in activity landscapes. The pressure difference originates in the flux of polar order and the gradient of swim velocity across the interface between regions of different activity. In contrast to motility-induced phase separation of ABPs with a homogeneous swim velocity, a critical point does not exist for an active-passive patch system, which continuously splits into a dense and a dilute phase with increasing activity. However, if the global density is so high that not all particles can be packed onto the inactive patch, then MIPS-like behavior is restored and the pressure is balanced again