Immobilisierung von Proteinen in elektrogesponnenen polymeren Nanofasern

Immobilisierung von Proteinen in elektrogesponnenen polymeren Nanofasern

Uniaxial orientierte diskotische Systeme und ihre optoelektronischen Eigenschaften

Für Anwendungen kolumnar-diskotischer Flüssigkristalle ist eine genaue Kontrolle über die Orientierung der entstehenden Strukturen Grundvoraussetzung. Die vorgelegte Arbeit beschäftigt sich mit Möglichkeiten zur uniaxialen Orientierung dieser Flüssigkristallklasse sowohl in dünnen, makroskopischen Filmen, als auch in Nanostrukturen. Eine uniaxial-liegende Orientierung kolumnar-diskotischer Flüssigkristalle in dünnen aufgeschleuderten Filmen ist durch die Verwendung von PTFE-Orientierungsschichten realisierbar. Dies stellt eine einfache filmbildende Methode für uniaxiale kolumnar-diskotische Schichten dar, wie sie beispielsweise in organischen Feldeffekttransistoren verwendet werden können. Nanostrukturen mit einer uniaxialen Ausrichtung des kolumnar-diskotischen Flüssigkristalls können mittels Benetzung nanoporöser Aluminiumoxidmembranen hergestellt werden. Hierbei sind sowohl uniaxial orientierte Nanodrähte als auch uniaxial orientierte Nanoröhrchen zugänglich

Richness of side-chain liquid-crystal polymers: From isotropic phase towards the identification of neglected solid-like properties in liquids

International audienceVery few studies concern the isotropic phase of Side-Chain Liquid-Crystalline Polymers (SCLCPs). However, the interest for the isotropic phase appears particularly obvious in flow experiments. Unforeseen shear-induced nematic phases are revealed away from the N-I transition temperature. The non-equilibrium nematic phase in the isotropic phase of SCLCP melts challenges the conventional timescales described in theoretical approaches and reveal very long timescales, neglected until now. This spectacular behavior is the starter of the present survey that reveals long range solid-like interactions up to the sub-millimetre scale. We address the question of the origin of this solid-like property by probing more particularly the non-equilibrium behavior of a polyacrylate substituted by a nitrobiphenyl group (PANO2). The comparison with a polybutylacrylate chain of the same degree of polymerization evidences that the solid-like response is exacerbated in SCLCPs. We conclude that the liquid crystal moieties interplay as efficient elastic connectors. Finally, we show that the " solid " character can be evidenced away from the glass transition temperature in glass formers and for the first time, in purely alkane chains above their crystallization temperature. We thus have probed collective elastic effects contained not only in the isotropic phase of SCLCPs, but also more generically in the liquid state of ordinary melts and of ordinary liquids

Biofunctionalized nanofibers using Arthrospira (Spirulina) biomass and biopolymer

Electrospun nanofibers composed of polymers have been extensively researched because of their scientific and technical applications. Commercially available polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHB-HV) copolymers are good choices for such nanofibers. We used a highly integrated method, by adjusting the properties of the spinning solutions, where the cyanophyte Arthrospira (formally Spirulina) was the single source for nanofiber biofunctionalization. We investigated nanofibers using PHB extracted from Spirulina and the bacteria Cupriavidus necator and compared the nanofibers to those made from commercially available PHB and PHB-HV. Our study assessed nanofiber formation and their selected thermal, mechanical, and optical properties. We found that nanofibers produced from Spirulina PHB and biofunctionalized with Spirulina biomass exhibited properties which were equal to or better than nanofibers made with commercially available PHB or PHB-HV. Our methodology is highly promising for nanofiber production and biofunctionalization and can be used in many industrial and life science applications

Extraction of poly(3-hydroxybutyrate) from Spirulina LEB 18 for developing nanofibers

The objective of this study was to extract poly(3-hydroxybutyrate) (PHB) from the microalgal biomass of Spirulina LEB 18 for the development of nanofibers by electrospinning method. Different extraction methods were tested. The maximum yield obtained was 30.1 ± 2%. It was possible to produce nanofibers with diameters between 826 ± 188 nm and 1,675 ± 194 nm. An increase in the nanofiber diameter occurred when a flow rate of 4.8 μL min-1 and a capillary diameter of 0.90 mm were used. The nanofibers produced had up to 34.4% of biomass additives, i.e., non-PHB materials. This can be advantageous, because it enables the conservation of microalgal biomass compounds with bioactive functions

Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form

Elektrogesponnene Nanofaser-Pheromon-Dispenser zur Regulierung des Bekreuzten Traubenwicklers (Lobesia botrana (Denis & Schiffermuller 1775))

Elektrogesponnene, organische Nanofasern sind neuartige Träger für flüchtige Signalstoffe zur biotechnischen Regulierung von Schadinsekten im integrierten und ökologischen Landbau. Der Einsatz von Pheromonen im Pflanzenschutz ist als eine umweltverträgliche Alternative zur Verwendung von chemisch-synthetischen Insektiziden oder als dessen Ergänzung bekannt. Die pheromonbeladenen Nanofasern wirken als Dispenser und sollten vom Konzept her eine möglichst kontinuierliche, räumlich und zeitlich gleichmäßige Abgaberate der flüchtigen Signalstoffe ermöglichen. Anforderungen sind, dass die Fasern wetterstabil sind, lang anhaltend funktionieren, einfach und kostengünstig ausgebracht sowie rückstandsfrei abgebaut werden können. Es werden Ergebnisse von Halb-Freilandversuchen präsentiert, die den Nachweis der prinzipiellen Funktionsfähigkeit von pheromonbeladenen, elektrogesponnenen Polymerfaserdispensern zur Insektenverwirrung erbringen. Der in unseren Versuchen eingesetzte Bekreuzte Traubenwickler, Lobesia botrana, dient uns lediglich als Modellorganismus. Eine Ausweitung dieser Technik auf andere Schadorganismen ist geplant