INMdok (Leibniz Institute for New Materials)
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Tailored polyurethane acrylate blend for large-scale and high-performance micropatterned dry adhesives
Get PDFContinuous roll-to-roll fabrication is essential for transferring the idea of bio-inspired, fibrillar dry adhesives into large-scale, synthetic, high-performance adhesive tapes. Toward this aim, we investigated process parameters that allow us to control the morphology and the resulting adhesion of mushroom-shaped micropatterned surfaces. Flexible silicone templates enabled the replication process of the polyurethane acrylate pre-polymer involving UV-light-induced cross-linking. For this paper, we particularly tailored the polyurethane acrylate pre-polymer by adding chemical components to tune UV curing kinetics and to reduce oxygen inhibition of radicals. We found that higher intensities of the UV light and faster reaction kinetics improved the quality of the microstructures, i.e., a larger cap diameter of the mushroom tips was achieved. The polymer blend U6E4 exhibited the fastest curing kinetics, which resulted in a micromorphology similar to that of the Ni-shim master structures. Best adhesion results were obtained for adhesive tapes made from U6E4 with 116 kPa pull-off stress, 1.4 N cm−1 peel strength and 71 kPa shear strength. In addition, repeated attachment–detachment tests over 100,000 cycles demonstrated strong robustness and reusability
Single layer graphene induces load-bearing molecular layering at the hexadecane-steel interface
Get PDFThe influence of a single layer graphene on the interface between a polished steel surface and the model lubricant hexadecane is explored by high-resolution force microscopy. Nanometer-scale friction is reduced by a factor of three on graphene compared to the steel substrate, with an ordered layer of hexadecane adsorbed on the graphene. Graphene furthermore induces a molecular ordering in the confined lubricant with an average range of 4–5 layers and with a strongly increased load-bearing capacity compared to the lubricant on the bare steel substrate
Combining Soft Polysilazanes with Melt-Shear Organization of Core–Shell Particles: On the Road to Polymer-Templated Porous Ceramics
Get PDFThe preparation of ordered macroporous SiCN ceramics has attracted significant interest and is an attractive area for various applications, e.g., in the fields of catalysis, gas adsorption, or membranes. Non-oxidic ceramics, such as SiCN, own a great stability based on the covalent bonds between the containing elements, which leads to interesting properties concerning resistance and stability at high temperature. Their peculiar properties have become more and more important for a manifold of applications, like catalysis or separation processes, at high temperatures. Within this work, a feasible approach for the preparation of ordered porous materials by taking advantage of polymer-derived ceramics is presented. To gain access to free-standing films consisting of porous ceramic materials, the combination of monodisperse organic polymer-based colloids with diameters of 130 nm and 180 nm featuring a processable preceramic polymer is essential. For this purpose, the tailored design of hybrid organic/inorganic particles featuring anchoring sites for a preceramic polymer in the soft shell material is developed. Moreover, polymer-based core particles are used as sacrificial template for the generation of pores, while the preceramic shell polymer can be converted to the ceramic matrix after thermal treatment. Two different routes for the polymer particles, which can be obtained by emulsion polymerization, are followed for covalently linking the preceramic polysilazane Durazane1800 (Merck, Germany): (i) Free radical polymerization and (ii) atom transfer radical polymerization (ATRP) conditions. These hybrid hard core/soft shell particles can be processed via the so-called melt-shear organization for the one-step preparation of free-standing particle films. A major advantage of this technique is the absence of any solvent or dispersion medium, enabling the core particles to merge into ordered particle stacks based on the soft preceramic shell. Subsequent ceramization of the colloidal crystal films leads to core particle degradation and transformation into porous ceramics with ceramic yields of 18–54%
A Self-Adhesive Elastomeric Wound Scaffold for Sensitive Adhesion to Tissue
Get PDFPressure sensitive adhesives based on silicone materials are used particularly for skin adhesion, e.g., the fixation of electrocardiogram (ECG) electrodes or wound dressings. However, adhesion to sensitive tissue structures is not sufficiently addressed due to the risk of damage or rupture. We propose an approach in which a poly-(dimethylsiloxane) (PDMS)-based soft skin adhesive (SSA) acts as cellular scaffold for wound healing. Due to the intrinsically low surface free energy of silicone elastomers, functionalization strategies are needed to promote the attachment and spreading of eukaryotic cells. In the present work, the effect of physical adsorption of three different proteins on the adhesive properties of the soft skin adhesive was investigated. Fibronectin adsorption slightly affects adhesion but significantly improves the cellular interaction of L929 murine fibroblasts with the polymeric surface. Composite films were successfully attached to explanted tympanic membranes. This demonstrates the potential of protein functionalized SSA to act as an adhesive scaffold in delicate biomedical application
General and selective deoxygenation by hydrogen using a reusable earth-abundant metal catalyst
Get PDFChemoselective deoxygenation by hydrogen is particularly challenging but crucial for an efficient late-stage modification of functionality-laden fine chemicals, natural products, or pharmaceuticals and the economic upgrading of biomass-derived molecules into fuels and chemicals. We report here on a reusable earth-abundant metal catalyst that permits highly chemoselective deoxygenation using inexpensive hydrogen gas. Primary, secondary, and tertiary alcohols as well as alkyl and aryl ketones and aldehydes can be selectively deoxygenated, even when part of complex natural products, pharmaceuticals, or biomass-derived platform molecules. The catalyst tolerates many functional groups including hydrogenation-sensitive examples. It is efficient, easy to handle, and conveniently synthesized from a specific bimetallic coordination compound and commercially available charcoal. Selective, sustainable, and cost-efficient deoxygenation under industrially viable conditions seems feasible
Optoregulation of collagen biosynthesis and remodeling in collagen associated diseases
Get PDFTissue regeneration and remodeling after damage requires enhanced collagen deposition at the site of damage. In collagen disorders like keratoconus and brittle bone disease this ability is lost due to collagen misfolding, poor crosslinking and deposition. For this purpose, tools that allow to control and regulate collagen biosynthesis and folding are required. Ideally, such tools should be collagen-specific and allow remote control, which available strategies fail to fulfill.In this context, a collagen-specific molecular chaperone, Hsp47, was chosen as it has multiple roles in collagen biosynthesis. Recombinant Hsp47 can be delivered in the endoplasmic reticulum of mammalian cells via KDEL receptor mediated endocytosis. Exogenous delivery of Hsp47 stimulates fibrillar collagen I, III and V in cells. A photoactivatable derivative of Hsp47 (H47Y<ONBY)was developed containing an un‐natural light‐responsive tyrosine (o‐nitro benzyl tyrosine (ONBY)),which renders Hsp47 inactive toward collagen binding. On-demand, localized and in situ activation of this tool, stimulating collagen production in disease-state cells, was tested in vitro.Also, this tool can be easily delivered precisely in cells of damage corneal tissue from keratoconus patients. Site-selective exposure after H47Y<ONBY treatment,allowing localized remodeling of the extracellular collagen matrix, was demonstrated ex vivo. This tool has potential to trigger collagen deposition in collagen deficient disorders.Tissue regeneration and remodeling after damage requires enhanced collagen deposition at the site of damage. In collagen disorders like keratoconus and brittle bone disease this ability is lost due to collagen misfolding, poor crosslinking and deposition. For this purpose, tools that allow to control and regulate collagen biosynthesis and folding are required. Ideally, such tools should be collagen-specific and allow remote control, which available strategies fail to fulfill.In this context, a collagen-specific molecular chaperone, Hsp47, was chosen as it has multiple roles in collagen biosynthesis. Recombinant Hsp47 can be delivered in the endoplasmic reticulum of mammalian cells via KDEL receptor mediated endocytosis. Exogenous delivery of Hsp47 stimulates fibrillar collagen I, III and V in cells. A photoactivatable derivative of Hsp47 (H47Y<ONBY)was developed containing an un‐natural light‐responsive tyrosine (o‐nitro benzyl tyrosine (ONBY)),which renders Hsp47 inactive toward collagen binding. On-demand, localized and in situ activation of this tool, stimulating collagen production in disease-state cells, was tested in vitro.Also, this tool can be easily delivered precisely in cells of damage corneal tissue from keratoconus patients. Site-selective exposure after H47Y<ONBY treatment,allowing localized remodeling of the extracellular collagen matrix, was demonstrated ex vivo. This tool has potential to trigger collagen deposition in collagen deficient disorders.Eine lokal erhöhte Kollagenablagerung ist für die Geweberegeneration und den Gewebeaufbau nach einer Schädigung notwendig. Bei Kollagenstörungen wie Keratokonus und Brittle Bone Disease geht diese Fähigkeit durch Fehlfaltung und schlechte Vernetzung verloren. Mittel und Wege werden benötigt, um die Kollagenbiosynthese und -faltung zu regulieren. Im Idealfall sind solche Werkzeuge kollagenspezifisch und von außen steuerbar, was derzeitige Strategien nicht erfüllen. In dieser Arbeit wurde das kollagenspezifische Chaperon Hsp47 ausgewählt, da es mehrere Rollen bei der Kollagenbiosynthese hat. Rekombinantes Hsp47 kann im endoplasmatischen Retikulum von Säugetierzellen über KDEL-Rezeptor-vermittelte Endozytose abgegeben werden. Die exogene Gabe von Hsp47 stimuliert in Zellen die Bildung von fibrillärem Kollagen I, III und V. Ein neues Hsp47 (H47Y <ONBY) wurde entwickelt mit nicht-natürlichem o-Nitro-Benzyltyrosin (ONBY) an der Tyr383- Position, die inaktiv ist für die Bindung und Bildung von Kollagen. In vitro wurde in Hsp47- defizienten Zellen bewiesen, dass die kontrollierte lokale Photoaktivierung dieser Variante die Ablagerung von Kollagen stimuliert. Außerdem wurde das neue HSP47 ex vivo in Zellen von Hornhautgewebe von Keratokonus-Patienten angewendet. Hier wurde nachgewiesen, dass durch lokale Belichtung nach H47Y <ONBY-Anwendung Kollagenfasern wiederherstellt werden. Das neue HSP47 hat das Potential, gezielte Kollagenablagerungen bei Störungen mit Kollagenmangel auszulösen
Annual report 2018 / Leibniz Institute for New Materials
Get PDFVorwort:
Es ist geschafft: Mit der Stellungnahme des Senats der Leibniz-Gemeinschaft und der Zustimmung der GWK zur weiteren Förderung des INM konnten wir 2018 das Evaluierungsverfahren unseres Instituts abschließen. Wir freuen uns über das hervorragende Ergebnis und haben bereits begonnen, die Empfehlungen der Evaluierung umzusetzen.
Das vergangene Jahr wurde wieder durch sehr schöne Erfolge geprägt: So gelang es dem Institut erstmals, einen ERC - Proof of Concept einzuwerben. Etwas Besonderes war die Auszeichnung von Aleeza Farrukh mit dem Leibniz-Promotionspreis. Dazu hat unser Kooperationspartner, Professor Robert McMeeking von der UC Santa Barbara, einen Humboldt-Alumni-Preis zum Aufbau eines innovativen Modellierungsnetzwerks am INM erhalten.
Inhaltlich nutzen wir die Zeit nach der Evaluierung, um neue Themen zu initiieren. Hierzu intensivieren wir unsere Zusammenarbeit auf dem Campus der Universität des Saarlandes: Dies gilt insbesondere für die Gebiete der biomedizinischen Materialien und der Materialien in der digitalen Umgebung. Für diese beiden Zukunftsbereiche des INM planen wir eine räumliche Erweiterung; mit den Baumaßnahmen soll 2020 begonnen werden.
Wir danken Ihnen für Ihre Unterstützung des INM im vergangenen Jahr und freuen uns, wenn Sie uns auch 2019 wieder begleiten werden
Soft inkjet circuits: rapid multi-material fabrication of soft circuits using a commodity inkjet printer
Get PDFDespite the increasing popularity of soft interactive devices, their fabrication remains complex and time consuming. We contribute a process for rapid do-it-yourself fabrication of soft circuits using a conventional desktop inkjet printer. It supports inkjet printing of circuits that are stretchable,ultra-thin,high resolution, and integrated with a wide variety of materials used for prototyping.We introduce multi-ink functional printing on a desktop printer for realizing multi-material devices, including conductive and isolating inks. We further present DIY techniques to enhance compatibility be-tween inks and substrates and the circuits’ elasticity. This enables circuits on a wide set of materials including temporary tattoo paper, textiles, and thermoplastic. Four application cases demonstrate versatile uses for realizing stretchable devices, e-textiles, body-based and re-shapeable interfaces
Targeted T1 Magnetic Resonance Imaging Contrast Enhancement with Extraordinarily Small CoFe2O4 Nanoparticles
Get PDFExtraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r2/r1 ratio suitable for a T1 contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T1 MRI. Our study demonstrates the potential of ESCIoNs as T1 MRI contrast agents
Magnetic-responsive bendable nozzles for open surface droplet manipulation
Get PDFThe handling of droplets in a controlled manner is essential to numerous technological and scientific applications. In this work, we present a new open-surface platform for droplet manipulation based on an array of bendable nozzles that are dynamically controlled by a magnetic field. The actuation of these nozzles is possible thanks to the magnetically responsive elastomeric composite which forms the tips of the nozzles; this is fabricated with Fe3O4 microparticles embedded in a polydimethylsiloxane matrix. The transport, mixing, and splitting of droplets can be controlled by bringing together and separating the tips of these nozzles under the action of a magnet. Additionally, the characteristic configuration for droplet mixing in this platform harnesses the kinetic energy from the feeding streams; this provided a remarkable reduction of 80% in the mixing time between drops of liquids about eight times more viscous than water, i.e., 6.5 mPa/s, when compared against the mixing between sessile drops of the same fluid