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Capillary stamping for bioanalytics and spatial manipulation of protein-protein interactions in live cellsPhilippi, Michael 27 September 2021 (has links)
Capillary stamping is a versatile patterning platform to create micron/sub-micron features on surfaces. When used in combination with mesoporous silica stamps, dot arrays with length scale characteristics matching those of various biomolecular organizations on living cells can be printed. Therefore, different types of ink with functional molecules were printed onto a glass surface and assessed toward their capability to enable an analysis of cellular interactions. Among the evaluated patterned surfaces were dot arrays generated with heterocyclic silanes, which react in a ring-opening reaction upon contact with hydroxyl-terminated surfaces and allow post-modifications of the stamped dot array. Similarly, functionalized proteins were stamped from an aqueous solution, analyzed in regards to specific geometric descriptors and overall contrast between dot and background. After the establishment of a robust patterning system, the stamped substrates were used to spatially manipulate protein-protein interactions in live cells. With the introduction of optogenetics, namely the photoactivatable iLID-system into HeLa cells, protein recruitment from the cytosol to the membrane-bound domains upon irradiation with light was investigated. The technique was also utilized to explore the determinants of Wnt signalosome formation. Wnt co-receptor Lrp6 expressed at the surface of living cells was successfully assembled into nanodot arrays. Strikingly, the co-receptor Fzd8 and the cytosolic scaffold proteins Axin1 and Disheveled2 were spontaneously recruited into the nanodot array to form spatially defined signalosomes in the absence of ligand pointing toward Liquid-Liquid Phase Separation driven signalosome assembly. Immunofluorescence staining confirmed ligand-independent Wnt/β-catenin signaling activated the nanodot arrays.
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Capillary nanostamping with spongy mesoporous silica stampsSchmidt, Mercedes 03 June 2019 (has links)
Many lithographic methods to pattern surfaces both by a mechanical manipulation of the surface or by printing functionalities in the form of particles or molecules have been developed and used in research. Examples for contact-lithographic methods are soft lithography and polymer-pen lithography. One of the main drawbacks of the these methods is the lateral dimension of the obtained pattern. Due to limitations of stamps, materials and the methods themselves, feature sizes of arrays consisting of discrete spots in the sub-micrometer range remain challenging. Another factor in the state-of-the-art contact-lithographic methods is the ex situ adsorption of ink prior to the stamping procedure and thus, an uninterrupted flow of ink cannot be guaranteed. As the variety of imaginable inks is wide and the appropriate solvent often appears to be of organic nature, state-of-the-art contact-lithographic methods are unable to print these inks. The elastomeric polymer stamps used within contact-lithographic methods swell or dissolve in contact with organic solvents. Often, contact-lithographic methods require expensive equipment or defined conditions, e.g. high vacuum or a solvent-enriched humidity, and cannot be carried out in a simple and efficient way under ambient conditions.
In this work, a new approach to generate patterned structures with feature sizes in the sub-micrometer range and spot-to-spot distances in the one-micron range is presented. Stamps with an integrated, continuous pore system generate the patterns while the ink is supplied through the capillaries of the stamp. The method of capillary nanostamping provides a simple and low-cost stamping procedure by the synthesis of spongy mesoporous silica stamps. Due to a continuous pore system within the stamp, the ink can be supplied continuously and even without a refilling system, the stamp itself serves as ink reservoir. This provides a continuous or intermittently ink supply for a stamping process with several stamping cycles without the need to refill the stamp. A new stamp or re-inking after one stamping cycle is not necessary. The stamping process is carried out manually by hand under ambient conditions. Due to the silica network, the stamps can be infiltrated with organic solvents.
The development of spongy mesoporous silica stamps for capillary nanostamping is presented in this work by demonstrating the progress from pure silica stamps in a typical well-known sol-gel synthesis to spongy and flexible silica stamps with a reduced network bonding and hydrophobic internal residues. For the proof of concept of capillary nanostamping with spongy mesoporous silica stamps, several different inks are stamped. All inks are chosen with respect to a potential application and consist of a volatile organic solvent to proof the stability of the stamps against these solvents, and a non-volatile component, which remains on the substrate surface after precipitation and drying of the solvent. As ink, a dispersion of C60 fullerenes in toluene is stamped onto perfluorinated glass slides. A solution of 1-dodecanethiol in ethanol is stamped onto a gold-coated glass with the outcome of a heterogeneous surface. As a model for nanoparticles, nanodiamonds dispersed in isopropanol are stamped and subsequently functionalized with a fluorescent dye in a click-reaction. A polymer and two different block copolymers dissolved in toluene/chloroform are stamped onto differently functionalized substrate surfaces to analyze the dependency of the nature of the substrate on the stamping results. In a final experiment, a solution of 17α-ethinylestradiol in acetonitrile is stamped as a model for an active pharmaceutical ingredient and subsequently detached from the substrate surface to obtain a defined nanodispersion.
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Nanoporous block copolymer stamps: design and applicationsHou, Peilong 10 December 2019 (has links)
This thesis focuses on the surface patterning by using nanoporous block copolymer (BCP) stamps. Polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) was used as model BCP. Nanoporous BCP stamps were fabricated by replication of lithographically patterned silicon molds. Nanopores inside of BCP stamps were generated by swelling‐induced pore formation. A method for scanner-based capillary stamping (SCS) with spongy nanoporous BCP stamps was developed. First, in the course of stamps design using replication molding of PS-b-P2VP against surface-modified macroporous silicon molds, PS-b-P2VP fiber rings remaining on the macroporous silicon molds were obtained that allow immobilization of water drops on the hydrophobically modified surfaces of the macroporous silicon molds. Water drops immobilized by these rings can be prevented from dewetting within the PS‐b‐P2VP fiber rings. Second, after spongy nanoporous PS-b-P2VP stamps had been obtained, preliminary experiments with non-inked PS-b-P2VP stamps revealed that parts of the stamps’ contact elements can be lithographically transferred onto counterpart surfaces. As a result, arrays of nanostructured submicron PS‐b‐P2VP dots with heights of ∼100 nm onto silicon wafers and glass slides were produced. Lastly, the SCS technique was developed, which overcomes the limitation of time-consuming re-inking procedures associated with classical soft lithography including microcontact printing (µCP) and polymer pen lithography (PPL) with solid stamps, as well as the limitations regarding throughput of scanning probe‐based serial writing approaches such as nanoscale dispensing (NADIS) and other micropipetting techniques. In addition, sizes of stamped droplets can be controlled by adjusting surface wettability and dwell time.
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PVDF Detectors in Supersonic Molecular Jet ExperimentsSaftien, Paul 21 July 2023 (has links)
Im Rahmen dieser Arbeit wurden verschiedene Teilchendetektoren zur Verwendung in einem gepulsten Überschallmolekularstrahlexperiment entworfen und hergestellt. In den hier durchgeführten Experimenten kollidiert ein Molekularstrahl mit einer sensitiven Detektoroberfläche, nämlich einer Polyvinylidenfluorid(PVDF)-Folie. Da PVDF sowohl pyroelektrisch wie auch piezoelektrisch ist, entstehen durch die Kollision der Molekularstrahlteilchen auf der Folie Oberflächenladungen. Vorteile von PVDF-Detektoren sind die hohe Effizient der Detektion, die Detektion von neutralen Atomen und Molekülen (eine Ionisierung der zu detektierenden Teilchen ist nicht notwendig), ein einfaches und leicht anzupassendes Detektordesign und außerdem eine schnelle Antwortzeit (im Mikrosekundenbereich). Da nur Ladungen im Bereich von wenigen Pikocoulomb generiert werden, sind verschiedene Verstärker getestet worden. Zur Analyse und Beschreibung des detektierten Signals wird der piezoelektrische Anteil durch ein Materialmodell in Verbindung mit einem schwingenden System, nämlich der erzwungenen Schwingung einer gedämpften Kreismembran, beschrieben. Der pyroelektrische Anteil wird durch einen Energieaustausch beschrieben. Durch die Ausnutzung des pyroelektrischen sowie des piezoelektrischen Effektes können zusätzliche wichtige Informationen wie zum Beispiel der Restitutionskoeffizient oder der Energieakkommodationkoeffizient experimentell erhalten werden. Zur Demonstration der Anwendungsmöglichkeiten sind Detektoren in verschiedenen Größen zur Messung von unterschiedlichen Strahleigenschaften verwendet worden. Untersucht wurde dabei die Strahlgeschwindigkeit von verschiedenen Edelgasen über einen großen Stagnationsdruck- und Stagnationstemperaturbereich. Außerdem wurden Strahlprofile zur Bestimmung der Strahldichte gemessen und mathematisch beschrieben. Zusätzlich wird eine Methode zur Bestimmung der Strahltemperatur mit Hilfe der Strahldichte und der Strahlgeschwindigkeit vorgestellt. / In this study, different particle detectors with a foil of polyvinylidene difluoride have been designed and built for use in a pulsed supersonic molecular jet experiment. Here, the molecular jet collides with the sensitive detector area and generates a charge. This generated charge is caused by the piezo- and the pyroelectric effect. Advantages of polyvinylidene difluoride detectors are a high detection efficiency, the detection of neutral atoms or molecules --- no ionization is required, a simple setup which can be easily incorporated in an existing experiment, an easy adjustment of the detector design because the shape and size can be changed easily, and a fast response-time in the sub-microsecond regime. Because the amount of charges generated is in the order of some picocoulomb, different amplifiers are used. In this analysis of the detected signal, the piezoelectric contribution is defined by the constitutive equations of piezoelectricity, which are used in combination with the concept of a driven damped circular membrane in order to obtain an analytic solution. The pyroelectric contribution is described via the exchanged energy. Because both the piezo- and the pyroelectric effects can be exploited, valuable additional information such as the coefficient of energy accommodation or the coefficient of restitution can be determined experimentally. In order to demonstrate the application possibilities of polyvinylidene difluoride detectors, detectors of different sizes are used as a local jet probe to determine different jet properties. The mean velocities of different rare gases for a wide range of source conditions are determined. Density profiles of various supersonic jets are measured and described mathematically in detail. In addition, both quantities, the velocity and the density, are used to determine the temperature of the supersonic jet.
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Ternary Rare-Earth Coinage Metal Arsenides LnTAs2, Sm2Cu3As3; Quaternary Arsenide Oxides Sm2CuAs3O and Selenides KGd2CuSe4, KLn2Cu3Se5, and K2Ln4Cu4Se9 (Ln = Y, La - Nd, Sm, Gd - Lu; T = Cu, Ag, Au): Syntheses, Crystal Structures and Physical PropertiesJemetio Feudjio, Jean Paul 22 August 2004 (has links) (PDF)
This thesis describes the syntheses, the crystal structures, and the physical properties of some new ternary and quaternary rare-earth coinage metal arsenides, selenides and oxides. All ternary compounds LnCu1+[delta]As2 (Ln = Y, La, Ce, Nd, Sm, Gd - Lu), LnAg1+[delta]As2 (Ln = La - Nd, Sm), and LnAuAs2 (Ln = Pr, Sm, Gd, Tb) adopt structures closely related to the HfCuSi2 type consisting of PbO-like layers of T and As atoms, square layers of As atoms and layers of Ln atoms separating the former two building units. All copper compounds of this series contain regular square nets of As atoms, whereas the respective nets in the silver and gold compounds are distorted. Two principally different patterns of distortion have been found: [As] zigzag chains in LnAgAs2 (Ln = Pr, Nd, Sm) and [As] cis-trans chains in LaAg1.01(1)As2, CeAgAs2, and PrAuAs2. Both patterns can undergo a further reduction of symmetry to end up with a pattern of As2 dumb-bells as can be seen in SmAuAs2, GdAuAs2, and TbAuAs2. Stoichiometric samples LnCuAs2 (Ln = Y, Pr, Nd, Sm, Gd, Tb, Dy, Er) have been used for measurements of the conductivity [rho], magnetic susceptibility [chi] and heat capacity cp. All investigated compounds exhibit metallic conductivity and, except for Y, order antiferromagnetically at temperatures below 10 K. In contrast to LnCuAs2 compounds, the silver compound CeAgAs2 shows semiconducting behavior throughout the temperature range from 4 to 350 K, whereas in PrAgAs2 metallic conductivity is preserved. The crystal structure of Sm2CuAs3O contains two different PbO-like layers formed either by Sm and O or Cu and As atoms. Both PbO-type layers are separated by sheets of Sm and distorted square nets of As atoms. The As atoms are arranged in planar zigzag chains, like those found in NdAgAs2. Sm2CuAs3O is thus the first quaternary rare-earth pnictide oxide with a distorted As net. The quaternary potassium rare-earth copper selenides KGd2CuSe4, KLn2Cu3Se5 (Ln = Ho, Er, Tm), and K2Ln4Cu4Se9 (Ln = Dy, Y) extend three series of previously described sulfide and selenide compounds. All three series adopt a three-dimensional tunnel structure built up by [LnSe6] octahedra and [CuSe4] tetrahedra. The K atoms reside in the tunnels with a bicapped trigonal prismatic coordination of eight Se atoms for KGd2CuSe4 and KLn2Cu3Se5 (Ln = Ho, Er, Tm), while for K2Ln4Cu4Se9 (Ln = Dy, Y), the K atoms are coordinated by seven Se atoms in monocappped trigonal prisms.
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Nitridonickelates: Preparation, Structure and PropertiesMehta, Akash 27 October 2005 (has links)
Low valent nickel (less than +1) complexes are rare in nature, however they are regularly encountered in nitridonickelate chemistry. Ternary alkaline earth nitridonickelates exhibit a variety of interesting crystal structures with respect to their covalently bonded nitridonickelate anionic framework. The coordination geometry of low valent nickel in these compounds presents a unique structural feature with nickel being in linear coordination by nitrogen atoms. The nitridonickelate frameworks of compounds investigated in this work are: Ba2[Ni3N2]: The first ternary alkaline earth nitridonickelates with 2D Ni-N anionic network. The formal oxidation state of Ni is +0.67. Ba2(Ba6N)[NiN]6: The structure is made of o1D helical Ni-N anionic chains. Also, the structural stability of this compound´s structure type was found to occur over a wide range of substitution of Ba by Ca and Sr; a max. of 70 percent Ba could be successfully replaced by Sr and Ca atoms retaining the same structure type. The formal oxidation state of Ni is +0.83. Ba[NiN] and the solid solution series Ba[CuxNi1-xN]: The structure is made of 1D zig-zag Ni-N chains. The solid-solution series is isostructural to Ba[NiN] at lower content of Cu while, at higher content it resembles Ba[CoN] structure type, however at very high Cu content it again transforms to Ba[NiN] structure type. The formal oxidation state of Ni is +1.0. Sr2[Ni(CN)N]: The structure consists of N-Ni-(CN) dumbbells. The compound is the first example of cyano-nitridonickelate. The formal oxidation state of Ni is 0. The handling of the ternary alkaline earth nitridonickelates in specific and also of the other nitridometalates in general suffers greatly due to their being air and moisture sensitive. This requires synthetic methods suitable for air and moisture sensitive samples and also the respective instrumental setup for the measurement of their physical properties under inert atmosphere. Up to now no comprehensive investigation of the physical properties of the ternary alkaline earth nitridonickelates has been made. In this work an emphasis was given to systematically investigate the physical properties of the ternary alkaline earth nitridonickelates and to understand their structure specific physical properties. The common features of the investigated ternary alkaline earth nitridonickelates are: 1. the low valency of nickel. 2. the linear coordination of Ni and octahedral coordination of N. During this investigation the low valent character of nickel was experimentally confirmed with the help of X-ray absorption spectroscopy and the interpretation of magnetic susceptibility data where the magnetic moments of the nickel atoms were always consistent with that of a low valent nickel species. The results obtained from the magnetic measurements and electrical conductivity shows that the alkaline earth nitridonickelates order antiferromagnetically at low temperatures and show temperature dependent metallic conductivity whereas the cyano-nitridonickelate Sr2[Ni(CN)N] does not order at low temperature, is paramagnetic, and exhibits semiconducting behaviour. This investigation has provided a better understanding of ternary alkaline earth nitridonickelates with respect to the different structure they exhibit and their associated physical properties. This work motivates to extend the investigations of the physical properties of other nitridometalates. These also exhibit different crystal structures with respect to their nitridometalate anionic framework and thus, structure specific physical properties are also to be expected.
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Ternary Rare-Earth Coinage Metal Arsenides LnTAs2, Sm2Cu3As3; Quaternary Arsenide Oxides Sm2CuAs3O and Selenides KGd2CuSe4, KLn2Cu3Se5, and K2Ln4Cu4Se9 (Ln = Y, La - Nd, Sm, Gd - Lu; T = Cu, Ag, Au): Syntheses, Crystal Structures and Physical PropertiesJemetio Feudjio, Jean Paul 16 September 2004 (has links)
This thesis describes the syntheses, the crystal structures, and the physical properties of some new ternary and quaternary rare-earth coinage metal arsenides, selenides and oxides. All ternary compounds LnCu1+[delta]As2 (Ln = Y, La, Ce, Nd, Sm, Gd - Lu), LnAg1+[delta]As2 (Ln = La - Nd, Sm), and LnAuAs2 (Ln = Pr, Sm, Gd, Tb) adopt structures closely related to the HfCuSi2 type consisting of PbO-like layers of T and As atoms, square layers of As atoms and layers of Ln atoms separating the former two building units. All copper compounds of this series contain regular square nets of As atoms, whereas the respective nets in the silver and gold compounds are distorted. Two principally different patterns of distortion have been found: [As] zigzag chains in LnAgAs2 (Ln = Pr, Nd, Sm) and [As] cis-trans chains in LaAg1.01(1)As2, CeAgAs2, and PrAuAs2. Both patterns can undergo a further reduction of symmetry to end up with a pattern of As2 dumb-bells as can be seen in SmAuAs2, GdAuAs2, and TbAuAs2. Stoichiometric samples LnCuAs2 (Ln = Y, Pr, Nd, Sm, Gd, Tb, Dy, Er) have been used for measurements of the conductivity [rho], magnetic susceptibility [chi] and heat capacity cp. All investigated compounds exhibit metallic conductivity and, except for Y, order antiferromagnetically at temperatures below 10 K. In contrast to LnCuAs2 compounds, the silver compound CeAgAs2 shows semiconducting behavior throughout the temperature range from 4 to 350 K, whereas in PrAgAs2 metallic conductivity is preserved. The crystal structure of Sm2CuAs3O contains two different PbO-like layers formed either by Sm and O or Cu and As atoms. Both PbO-type layers are separated by sheets of Sm and distorted square nets of As atoms. The As atoms are arranged in planar zigzag chains, like those found in NdAgAs2. Sm2CuAs3O is thus the first quaternary rare-earth pnictide oxide with a distorted As net. The quaternary potassium rare-earth copper selenides KGd2CuSe4, KLn2Cu3Se5 (Ln = Ho, Er, Tm), and K2Ln4Cu4Se9 (Ln = Dy, Y) extend three series of previously described sulfide and selenide compounds. All three series adopt a three-dimensional tunnel structure built up by [LnSe6] octahedra and [CuSe4] tetrahedra. The K atoms reside in the tunnels with a bicapped trigonal prismatic coordination of eight Se atoms for KGd2CuSe4 and KLn2Cu3Se5 (Ln = Ho, Er, Tm), while for K2Ln4Cu4Se9 (Ln = Dy, Y), the K atoms are coordinated by seven Se atoms in monocappped trigonal prisms.
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C^C* cyclometalated platinum(II) N-heterocyclic carbene complexes with a sterically demanding β-diketonato ligand – synthesis, characterization and photophysical propertiesStrassner, Thomas, Metz, S., Wagenblast, G., Münster, Ingo, Tenne, Mario 16 December 2015 (has links) (PDF)
Neutral cyclometalated platinum(II) N-heterocyclic carbene complexes [Pt(C^C*)(O^O)] with C^C* ligands based on 1-phenyl-1,2,4-triazol-5-ylidene and 4-phenyl-1,2,4-triazol-5-ylidene, as well as acetylacetonato (O^O = acac) and 1,3-bis(2,4,6-trimethylphenyl)propan-1,3-dionato (O^O = mesacac) ancillary ligands were synthesized and characterized. All complexes are emissive at room temperature in a poly(methyl methacrylate) (PMMA) matrix with emission maxima in the blue region of the spectrum. High quantum efficiencies and short decay times were observed for all complexes with mesacac ancillary ligands. The sterically demanding mesityl groups of the mesacac ligand effectively prevent molecular stacking. The emission behavior of these emitters is in general independent of the position of the nitrogen in the backbone of the N-heterocyclic carbene (NHC) unit and a variety of substituents in 4-position of the phenyl unit, meta to the cyclometalating bond.
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Cyber-Physical Production Systems - Herausforderungen bei Modellierung und Informationsmanagement [Präsentationsfolien]Gerhard, Detlef 10 December 2016 (has links) (PDF)
No description available.
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Synthetic peptides derived from decorin as building blocks for biomaterials based on supramolecular interactionsFederico, Stefania January 2011 (has links)
In this work, the development of a new molecular building block, based on synthetic peptides derived from decorin, is presented. These peptides represent a promising basis for the design of polymer-based biomaterials that mimic the ECM on a molecular level and exploit specific biological recognition for technical applications.
Multiple sequence alignments of the internal repeats of decorin that formed the inner and outer surface of the arch-shaped protein were used to develop consensus sequences. These sequences contained conserved sequence motifs that are likely to be related to structural and functional features of the protein. Peptides representative for the consensus sequences were synthesized by microwave-assisted solid phase peptide synthesis and purified by RP-HPLC, with purities higher than 95 mol%. After confirming the desired masses by MALDI-TOF-MS, the primary structure of each peptide was investigated by 1H and 2D NMR, from which a full assignment of the chemical shifts was obtained. The characterization of the peptides conformation in solution was performed by CD spectroscopy, which demonstrated that using TFE, the peptides from the outer surface of decorin show a high propensity to fold into helical structures as observed in the original protein. To the contrary, the peptides from the inner surface did not show propensity to form stable secondary structure. The investigation of the binding capability of the peptides to Collagen I was performed by surface plasmon resonance analyses, from which all but one of the peptides representing the inner surface of decorin showed binding affinity to collagen with values of dissociation constant between 2•10-7 M and 2.3•10-4 M. On the other hand, the peptides representative for the outer surface of decorin did not show any significant interaction to collagen.
This information was then used to develop experimental demonstration for the binding capabilities of the peptides from the inner surface of decorin to collagen even when used in more complicated situations close to possible appications. With this purpose, the peptide (LRELHLNNN) which showed the highest binding affinity to collagen (2•10-7 M) was functionalized with an N-terminal triple bond in order to obtain a peptide dimer via copper(I)-catalyzed cycloaddition reaction with 4,4'-diazidostilbene-2,2'-disulfonic acid. Rheological measurements showed that the presence of the peptide dimer was able to enhance the elastic modulus (G') of a collagen gel from ~ 600 Pa (collagen alone) to ~ 2700 Pa (collagen and peptide dimer). Moreover, it was shown that the mechanical properties of a collagen gel can be tailored by using different molar ratios of peptide dimer respect to collagen.
The same peptide, functionalized with the triple bond, was used to obtain a peptide-dye conjugate by coupling it with N-(5'-azidopentanoyl)-5-aminofluorescein. An aqueous solution (5 vol% methanol) of the peptide dye conjugate was injected into a collagen and a hyaluronic acid (HA) gel and images of fluorescence detection showed that the diffusion of the peptide was slower in the collagen gel compared to the HA gel.
The third experimental demonstration was gained using the peptide (LSELRLHNN) which showed the lower binding affinity (2.3•10-4 M) to collagen. This peptide was grafted to hyaluronic acid via EDC-chemistry, with a degree of functionalization of 7 ± 2 mol% as calculated by 1H-NMR. The grafting was further confirmed by FTIR and TGA measurements, which showed that the onset of decomposition for the HA-g-peptide decreased by 10 °C compared to the native HA. Rheological measurements showed that the elastic modulus of a system based on collagen and HA-g-peptide increased by almost two order of magnitude (G' = 200 Pa) compared to a system based on collagen and HA (G' = 0.9 Pa).
Overall, this study showed that the synthetic peptides, which were identified from decorin, can be applied as potential building blocks for biomimetic materials that function via biological recognition. / In dieser Arbeit wird das Design, die Synthese und Analyse neuer molekularer Bausteine für Biomaterialien basierend auf synthetischen, von Decorin abgeleiteten Peptiden beschrieben. Diese Peptide sind deshalb als Baustein für polymer-basierte Biomaterialien von besonderem Interesse, da sie die extrazelluläre Matrix (ECM) auf molekularer Ebene nachempfinden und spezifische, biologische wichtige Interaktionen für technische Anwendungen nutzbar machen.
Das Alignment multipler Sequenzen der internen Repeats von Decorin, die jeweils die innere bzw. äußere Seite des sichelförmigen Decorins bilden, wurde genutzt, um Konsensus-Sequenzen zu definieren. Diese Sequenzen beinhalten stark konservierte Sequenzmotive, die wahrscheinlich wichtig für Struktur und Funktion des Proteins sind. Ausgewählte Peptide, die repräsentativ für die Konsensus-Sequenzen sind, wurden dann mittels Mikrowellen unterstützter Festphasensynthese synthetisiert und mit RP-HPLC aufgereinigt, so dass Peptide mit Reinheiten ≥ 95 mol% erhalten wurden. Die Peptide wurden per MALDI-TOF-MS sowie 1D und 2D NMR Spektroskopie charakterisiert, wobei die Zuordnung der chemischen Verschiebungen zu einzelnen Protonen und Kohlenstoffen aus den 2D NMR Experimenten erfolgte. In Lösung wurden die Peptide zudem mit CD Spektroskopie untersucht, wobei gezeigt werden konnte, dass nur Peptide, die von der äußeren Seite des Decorins abgeleitet wurden, sich durch Zugabe von 2,2,2-Trifluorethanol zu α-Helices falten. Diese Faltung ist auch in der Röntgenstruktur bei den korrespondierenden Abschnitten zu finden. Im Gegensatz dazu zeigten Peptide, die von der inneren Seite des Decorins abgeleitet wurden, keine stabilen Sekundärstrukturen in Lösung (β-Faltblattstruktur in der Röntgenstruktur). Bindungsstudien der Peptide zu Kollagen I wurden mit Oberflächenplasmonenresonanz durchgeführt, wobei gezeigt werden konnte, dass alle bis auf ein Peptid, die von der innneren Seite abgeleitet wurden, an Kollagen mit Dissoziationskonstanten von 2•10-7 M bis 2.3•10-4 M binden, während Peptide, die für die äußere Seite von Decorin repräsentativ sind, keine Bindung an Kollagen I zeigten.
Diese Information wurde genutzt, um experimentelle Demonstrationsobjekte dieser Interaktion in komplexeren, einer späteren Anwendung näheren Situation, zu entwickeln. Dazu wurde das Peptide LRELHLNNN, welches die stärkste Bindung zu Kollagen I zeigte (KD = 2•10-7 M), N-terminal mit einer Alkinbindung funktionalisiert, so dass durch Kupfer (I) katalysierte Reaktion mit 4,4'-Diazidostilben-2,2'-disulfonsäure ein Peptid-Dimer erhalten werden konnte. Rheologische Untersuchungen zeigten, dass durch Zugabe des Peptid-Dimers der Elastizitätsmodul G' von Kollagen-Gelen von ~ 600 Pa (nur Kollagen) auf ~ 2700 Pa (Kollagen und Peptide-Dimer) gesteigert werden konnte. Darüber hinaus konnte gezeigt werden, dass die Veränderung der mechanischen Eigenschaften der Gele durch Veränderung des Kollagen:Peptid-Dimer Verhältnisses angepasst werden konnten.
Das gleiche, mit einer Alkin-Bindung funktionaliserte Peptid wurde dann zur Darstellung eines Peptid-Fluorescein Konjugats genutzt, indem es mit N-(5'-azidopentanoyl)-5-aminofluorescein umgesetzt wurde. Eine wässrige Lösung des Peptid-Farbstoff-Konjugats wurde dann in Kollagen- bzw. Hyaluronsäuregele injiziert. Die Diffusion des Peptid-Farbstoff-Konjugats war in Kollagengelen im Vergleich zu Hyaluronsäuregelen deutlich verlangsamt.
Das dritte Demonstrationsobjekt wurde erhalten, indem das Peptid LSELRLHNN, welches die geringste Bindung an Kollagen zeigte (KD = 2.3•10-4 M), auf Hyaluronsäure (HA) gegrafted wurde. Die Reaktion wurde durch Carbodiimid-mediierte Kupplung erreicht, und ein Funktionalisierungsgrad von 7 ± 2 mol% wurde durch Integration der 1H-NMR Spektren bestimmt. Das erfolgreiche Grafting wurde durch FTIR- und TGA-Untersuchungen bestätigt. In letzteren wurde gezeigt, dass der thermische Abbau durch das Grafting bei etwas niedrigeren Temperaturen beginnt als der Abbau reiner Hyaluronsäure (ΔT = 10 °C). Rheologische Untersuchungen zeigten, dass ein System aus Kollagen und HA-g-Peptid ein um zwei Größenordnungen höheren Elastizitätsmodul G' hat (G' = 200 Pa) als Systeme, die aus einer physikalischen Mischung von Kollagen und HA bestehen (G' = 0.9 Pa).
Zusammenfassend konnte gezeigt werden, dass die Peptide, die von Decorin abgeleitet wurden, als Kollagen-bindende Bausteine für biomimetische Materialien genutzt werden können.
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