Thesis (M.Sc.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: This thesis is a written record of an investigation into the self-assembly of organic monomers in amphiphilic solutions. The polymerizable surfactant sodium 10-undecenoate was used alone and with different concentrations of styrene and methyl methacrylate monomers and phenyl acetophenone initiator to investigate single particle formation from a simple amphiphilic self-assembly. Reactions were carried out under either ultra-violet light or gamma irradiation. It was shown that copolymerization between the surfactant and the monomers did not occur to any significant extent. This meant that inclusion of easily modifiable carboxyl functionalities in the polymer by incorporation of the carboxylate surfactant could not be quantified. Star-like particles were found. The shape of the particles formed, was the result of surfactant self-assembly to create self-assembled particles rather than templating of polymeric material. Polymerization of the unsaturated surfactant particles occurred to low conversions only. Analyses of formed particles were carried out using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, field emission scanning electron microscopy and light microscopy for structure observation. The techniques of energy dispersive analysis by x-rays, particle SIze analysis, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared analysis, nuclear magnetic resonance, small angle x-ray scattering and inductively coupled plasma (for counter-ion analysis) were used for the gathering of physical data. / AFRIKAANSE OPSOMMING: Hierdie studie is 'n geskrewe rekord van 'n ondersoek van die self-aneensetting van organiese monomere in amfifiliese oplossings. In die ondersoek is die polimeeriseerbare seep natrium 10-undekenoaat alleen en saam met verskillende konsentrasies van monomere en feniel asetofenoon gebruik om enkelpartikel formasie vanaf 'n eenvoudige amfifiliese templaat te ondersoek. Reaksies is uitgevoer onder of ultra-violet lig, of gamma bestraling. Dit is bewys dat kopolimerisasie tussen die seep en die monomere me III emge merkwaardige hoeveelhede plaasgevind het nie. Dit beteken dat insluiting van maklik veranderbare karboksiel funksionele groepe in die polimeer deur middel van insluiting van die karboksilaat seep nie meetbaar was nie. Ster-vormige partikels is gevind. Dit is getoon dat die vorm van die partikels wat in die vroeëre werk verkry is, die resultaat van seep self-aaneensetting, eerder as templatering van polimeriese materiaal is. Polimerisasie van die seep partikels het net tot lae vlak van omskakeling plaasgevind. Analise van die gevormde partikels is uitgevoer deur middel van skandeer elektron mikroskopie; transmissie elektronmikroskopie; atomiese kragmikroskopie; veldemissie skandeer elektron mieroskopie en ligmikroskopie vir struktuur bepalings. Die tegnieke van energie dispersie analiese deur middel van x-strale; deeltjie grootte analise; differensiaal skandeer kalorimetrie; termogravimetriese analise; Fourier transformasie infra rooi analiese; kern magnetiese resonansie; klein hoek x-straal diffraksie en induktief-gekoppelde plasma (vir teenioon analise) is gebruik om fisiese data te versamel.

No description available.

Thèse de doctorat : Médecine. Biologie cellulaire et moléculaire : Université de Nantes : 2006. / Bibliogr.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2014. / The exposure of organisms to environmental stresses and pathogens results in rapid activation of a range of defensive pathways that act as part of the innate immune system. The most common innate immunity response is the activation of cationic amphiphilic peptides in response to microbial infection. Moreover, cationic amphiphilic peptides possess desirable attributes for the pharmaceutical development of cancer-selective drugs. They selectively and rapidly kill cancer cells without killing normal mammalian cells and have a broad spectrum of mechanisms of action. The aim of this exploratory study was to screen for cationic amphiphilic peptides with anti-proliferative activity that is induced by genotoxicity. GeneFishing® technology, 2-D gel analysis and bioassays were used to identify and analyse molecules induced in response to genotoxic stress in an embryonic cell line originating from the dung beetle Euoniticellus intermedius. Bioassay results revealed that the cell line has constitutive expression of probable cationic amphiphilic proteins that are further induced by camptothecin treatment. GeneFishing® and 2-D gel analysis showed changes in gene expression at both transcriptional and translational levels, respectively. Overall, the study failed to identify the involvement or induction of cationic amphiphilic peptides in response to genotoxic stress. However, gene expression analyses revealed changes in the expression of classes of proteins involved in stress response, oxidative phosphorylation, mitochondrial maintenance, protein translation, cytoskeletal proteins and immunophilins. The results show that the cell line constitutively expresses probable cationic amphiphilic peptides which are further induced by camptothecin.

Ce travail de thèse décrit la préparation et l'étude des propriétés d'auto-assemblage de nouveaux amphiphiles fonctionnalisés par des sucres. Des glycosides propargyliques du lactose et de la N-acétyl-glucosamine ont été conjugués par chimie click (cycloaddition de Huisgen catalysée par des sels de cuivre) à des dérivés de poly(ethyleneglycol) dont une des extrémités a au préalable été modifiée par une fonction azide et l'autre par un bloc hydrophobe de type polyphénylène ou bien aliphatique. Après une caractérisation par résonance magnétique nucléaire et spectrométrie de masse, les propriétés d'auto-assemblage de ces amphiphiles ont été étudiées par diffusion dynamique de la lumière (DLS), diffraction des rayons-X aux petits angles (SAXS) et microscopie électronique. Il a été montré qu'en phase aqueuse, les systèmes amphiphiles dérivés du PEG 900 s'auto-assemblent pour former de micelles de taille extrêmement régulière dont le diamètre moyen est de l'ordre de 10 nm. La présence et la biodisponibilité des sucres à la surface de ces nanoparticules ont également pu être démontrées par diffusion dynamique de la lumière avec les lectines PNA et WGA. Les interactions spécifiques observées entre les lectines et micelles associées aux propriétés d'encapsulation de ce type de nanoparticules permettent d'imaginer de futures applications pour la délivrance de médicaments ou encore l'imagerie médicale.

Thèse de doctorat : Sciences chimiques. Chimie-physique : Bordeaux 1 : 2008. / Titre provenant de l'écran-titre.

Thèse de doctorat : Chimie : Strasbourg : 2009. / Titre provenant de l'écran-titre. Bibliogr. 9 p.

Reproduction de : Thèse de doctorat : Physique : Lyon 1 : 2006. / Titre provenant de l'écran titre. 115 réf. bibliogr.

Universiẗat, Diss., 2002--Jena.

Isolating chemically-reactive sites into nanosized compartments is an important mode of control used by Nature to perform chemical transformations with extremely high yields and selectivity. Biological systems are fundamentally organized as bounded and isolated nano- and micro-sized environments featuring distinct localized properties, such as steric crowding, polarity, hydrophobicity, potential for molecular recognition, or pH. Through this compartmentalization, reaction substrates are sequestered away from interfering factors and competing substrates, or are physically prevented from forming alternative products or favoring specific pathways. Inspired by Nature, chemists have explored the rational design and application of various nanocompartments. This work explores three types of nanoconfinement systems capable of catalysis and specific transport: surfactant micelles, block-copolymer micelles, and hollow inorganic nanoparticles. The surfactant micelles are designed as part of a system of self-replicating micelles and are used to show how the chirality of the confinement system effects reaction kinetics. Simple click chemistry between a hydrophilic chiral head and a hydrophobic tail is used to produce an amphiphile under biphasic conditions. Once the product achieves critical micelle concentration, stable micelles can form. These micelles subsequently compartmentalize and pre-concentrate hydrophobic substrates, increasing the reaction rate and resulting in the self-propagation of the micellar structures and their chiralities. The next system explores block-copolymer micelles that are made up of a hydrophobic saturated fluorocarbon block and a hydrophilic block. The amphiphilic copolymers can form aggregates in water and, because of properties unique to the hydrophobic block, this system also increases oxygen solubility in water. Different fluorocarbon monomers are discussed and it was found that the structure of the fluorinated monomer, temperature, and pH effect aggregation behavior and the concentration of dissolved oxygen. Additionally, varying the pH of the system could be used to trigger oxygen release. Similar to the block-copolymer micelles, the hollow inorganic nanoparticles were designed to transport oxygen. Here, hollow silica nanoparticles were designed with a fluorinated interior surface and a hydrophilic exterior. This design allows for highly dispersible nanoparticles in water and facilitates the uptake of saturated fluorocarbon liquids into their cores. Once the saturated fluorocarbon is incorporated, the system can les to increases in oxygen solubility.