Užití biologických materiálů k náhradě tkání v plastické chirurgii ! Abstrakt v angličtině Background: Biological meshes are biomaterials consisted of extracellular matrix and used in surgery particularly for hernia treatment or thoracic wall reconstruction. They are capable of vascularization, that decreases risk of infection, expecially when used in contaminated fields. This study compared the strength of incorporation and biocompatibility of two porcine-derived grafts (cross-linked and non-cross-linked) in a rat hernia model. In addition, we hypothesized that combination of extracellular matrices with autologous mesenchymal stem cells used for hernia repair would result in increased vascularization and increased strength of incorporation. Methods: Standardized 2 x 4 cm fascial defect was created in 42 Wistar rats and repaired with a cross-linked or a non-cross-linked graft either enriched or non-enriched with stem cells. The rats were sacrificed 3, 6 and 12 months later. The strength of incorporation, vascularization, cellular invasion, foreign body reaction and capsule formation were evaluated. Results: Comparison of stem cell enriched and non-enriched groups showed no significant differences in the capsule thickness, foreign body reaction, cellularization or vascularization. In the non-cross-linked...

In the present work, a super water-absorbent poly(acrylic acid) was synthetized by inverse suspension polymerization, using Span60 as the dispersant, toluene as the dispersing organic phase, trimethylolpropane triacrylate as the crosslinking agent, and sodium persulfate as the initiator. The synthesis was conducted in a small-scale glass reactor operated in semi-batch mode. The following reaction conditions were evaluated: effects of initiator concentration, temperature, percentage of multifunctional cross-linker agent and monomer concentration. Also, two important properties were determined, conversion and gel fraction. A kinetic model including a population balance was employed to simulate the process. The proposed model uses the numerical fractionation technique and is capable of predicting the pre-gel and post-gel properties, the effect of the crosslinking agent level on the polymer properties and the dynamic of gelation. The model was compared with the experimental results and showed a satisfactory representation of the system after parameter adjusting. / No presente trabalho, o poli (ácido acrílico) super-absorvente foi sintetizado por polimerização em suspensão inversa, usando Span 60 como o dispersante, tolueno como fase orgânica, trimetilolpropano triacrilato como agente de reticulação e persulfato de sódio como iniciador. A síntese foi conduzida num reator de vidro em escala de bancada, operado em modo semi-batelada-batelada. As seguintes condições da reação foram avaliadas: os efeitos da concentração de iniciador, a temperatura, a porcentagem de agente de reticulação multifuncional e a concentração de monómero. Além disso, foram determinadas propriedades importantes, como a conversão e a fração de gel. Da mesma forma, foi desenvolvido um modelo de balanço populacional para simular o processo em conjunto com a técnica de fracionamento numérico, que é capaz de prever as propriedades pré-gel e pós-gel, o efeito do nível do agente de reticulação no polímero e as propriedades da dinâmica de gelificação. O modelo foi comparado com os resultados experimentais e mostrou uma representação satisfatória do sistema após o ajuste dos parâmetros.

L’élucidation des interactions non-covalentes des complexes biologiques revêt d’une importance majeure dans la compréhension du fonctionnement cellulaire. L’objectif de ce travail de thèse est d’approfondir les développements de la spectrométrie de masse (MS) pour l’étude de ces complexes, que ce soit par MALDI-MS (la désorption-ionisation laser assistée par matrice) ou par ESI-MS (l’ionisation électrospray). Ce travail s’est articulé autour de trois axes : i) étude de la stœchiométrie et de la topologie du complexe SAGA HAT (Spt-Ada-Gcn5 Acétyltransferase, module Histone Acétyl Transferase) par pontage chimique couplé à la MS ; ii) suivi de la dimérisation des complexes formés par RAR-RXR (récepteur de l’acide rétinoïque - récepteur X des rétinoïdes) avec différents ADNs ; iii) mesure de la constante de dissociation des complexes RXR-ligand. Les méthodologies développées ont permis de repousser le potentiel de la MS et d’obtenir des informations structurales des complexes biologiques. / Elucidation of non-covalent interactions of biological complexes takes on great importance for the understanding of cellular function. The purpose of this thesis is a further development of mass spectrometry (MS) for the study of these complexes, either by MALDI-MS (matrix-assisted laser desorption-ionization) or by ESI-MS (electrospray ionization). This work was focused on three main lines: i) study of the stoichiometry and the topology of SAGA HAT (Spt-Ada-Gcn5 Acetyltransferase, Histone Acetyl Transferase module) complex by chemical cross-linking coupled to MS; ii) monitoring the dimerization of the complexes formed by RAR-RXR (retinoic acid receptor - retinoid X receptor) with different DNAs; iii) measuring the dissociation constant of RXR-ligand complexes. The developed methodologies made it possible to expand the potential of MS and get insight into structure of biological complexes.

Dans ce travail, le comportement des protéines de pois vis-à-vis de la gélification enzymatique par la transglutaminase microbienne (MTGase) a été évalué à l’état natif et après dénaturation (réduction chimique ou thermo-dénaturation). L’application finale concernait la formation de microparticules protéiques permettant d’encapsuler la riboflavine, choisie comme molécule active hydrophile modèle. Le procédé d’extraction des fractions protéiques de pois a été optimisé de manière à affecter le moins possible la structure des protéines et de récupérer des fractions natives riches en albumines (Alb) et en globulines (Glob), ou leur mélange. La mise en place des méthodes de suivi de la réaction enzymatique a permis de mettre en évidence leur complémentarité ainsi que leurs limites. Deux nouvelles méthodes de suivi de la réticulation enzymatique ont été développées. L’une basé sur la RMN permet la détermination simultanée de la quantité du fragment glutamine-lysine, produit de la réaction enzymatique, et le degré de réticulation ; l’autre méthode, basée sur les techniques de mesure de taille (SDS-PAGE et DLS), permet de visualiser les liaisons intramoléculaires. L’étude du traitement enzymatique appliqué aux fractions Alb et Glob de pois à l’état natif et dénaturé, ainsi qu’en mélange natif, a montré que la réaction enzymatique est fortement liée à la structure et à la conformation des protéines. Contrairement à la fraction Alb, la fraction Glob constitue un bon substrat pour la MTGase et la réticulation met en jeu des sous-unités constitutives des globulines différentes pour chaque condition de traitement. Néanmoins, la fraction Alb peut être utilisée en tant que booster de réaction enzymatique ce qui peut faire l’objet d’une voie innovante d’amélioration de la susceptibilité des protéines vis-à-vis de la MTGase. Le mécanisme semble basé sur un phénomène d’affinité sélective. Les bonnes propriétés mécaniques et de capacité de rétention d’eau du gel de la fraction protéique de pois totale ont été exploitées pour produire des microparticules à partir de la dispersion de la solution protéique sous forme d’émulsion suivie d’une gélification enzymatique par la MTGase. Les microparticules ont été pratiquement insolubles dans les milieux gastro-intestinaux en absence d’enzymes et lentement dégradable en présence d’enzymes. La libération de la riboflavine est gouvernée par un phénomène de diffusion en absence d’enzyme et de dégradation de support en présence d’enzymes selon des cinétiques compatibles avec des applications nutraceutiques. / In this work, pea proteins behavior toward enzymatic gelation by microbial transglutaminase (MTGase) was studied at native state and after denaturation (chemical reduction or thermal denaturation). The final application was the formation of protein microparticules to encapsulate riboflavin, chosen as hydrophilic active molecule model. The extraction process of the pea protein fractions has been optimized in such a way to minimize as possible protein denaturation and recover native fractions rich in albumin (Alb) and globulin (Glob) or a mixture of both.The setting up of the enzymatic reaction monitoring methods has brought out their complementarity as well as their limits. Two new monitoring methods of enzymatic cross-linking reaction have been developed. The first one, based on the NMR, allows to the simultaneous determination of the glutamine-lysine isopeptide bond, product of the enzymatic reaction, and the degree of crosslinking; the second method, based on size measuring techniques (SDS-PAGE and DLS), permit to view the intramolecular links. The study of enzymatic treatment applied to pea Alb and Glob at the native and denatured states, as well as thier native mixture showed that the enzymatic reaction is strongly related to the structure and conformation of proteins. Unlike Alb, the Glob fraction is a good substrate to transglutaminase and crosslinking reaction involves different subunits constituting globulins for each treatment condition. However, the Alb can be used as a booster of enzyme reaction which can be an innovative way for improving the proteins susceptibility toward transglutaminase treatment. The mechanism seems to be based on a selective affinity phenomenon. The good mechanical properties and water holding capacity of total pea proteins gel have been exploited to produce microparticles from a water-in-oil emulsion followed by enzymatic gelation. The produced microparticles were practically insoluble in gastrointestinal media in the absence of enzymes and slowly degradable in the presence of enzymes. The release mechanisms of riboflavin in digestive environments are governed by a diffusion phenomenon in the absence of enzymes and by support degradation phenomenon in the presence of enzymes according to kinetics compatible with nutraceutical applications.

Dans le cadre de cette thèse, les dérivés d’huiles végétales sont utilisés pour la synthèse de bioplastifiants bio-résistants pour le PVC d’une part et la plastification et la réticulation d’un élastomère d’autre part (EPDM). Les huiles ont été choisies comme matières premières renouvelables car elles ont des fonctions esters qui permettent la solubilisation du PVC et des chaines grasses compatibles avec l’EPDM. Les réactions d’ouvertures d’époxydes d’esters gras en di-esters (symétriques et dissymétriques) ont été étudiées et principalement appliquées à la plastification du PVC. L’ouverture des époxydes d’esters gras en éther-esters a aussi été étudiée, principalement pour la plastification de l’EPDM. Les conditions réactionnelles ont été optimisées par l’étude de catalyseurs, homogène (TBACl) et hétérogène (TiO2) pour l’ouverture en hydroxy-ester, et par des résines sulfoniques pour l’ouverture en éther et pour l’estérification des hydroxyles résiduels. Une large variété de réactifs choisis suivant l’application désirée a été utilisée. Le dérivé cyclohexanoate/acétate d’esters méthyliques de colza présente les meilleures propriétés plastifiantes pour le PVC mais il n’est malheureusement pas biorésistant. Les dérivés éther-ester ne sont pas stables thermiquement et ne permettent pas la plastification de l’EPDM. Un dérivé di-insaturé et peu polaire (oléate d’oléyle) a été synthétisé en vue de la plastification et la réticulation de l’EPDM. Plusieurs réactions ont été examinées pour lier l’huile et le polymère (hydrosilylation, ène-réaction et métathèse) mais la réactivité est trop faible pour permettre la réticulation / During this thesis, derivatives of vegetable oils are used to synthesize bio-resistant bio plasticizers for PVC and plasticizer / cross linker for an elastomer (EPDM). The oils possess ester functional groups which allow the solubilization of PVC and fatty chains compatible with EPDM. The reactions of epoxide ring-opening of fatty esters to di esters (symmetrical and asymmetrical) have been studied and applied mainly to the plasticization of PVC. The ring-opening of epoxides of fatty esters to ether-esters has also been studied, primarily for plasticization of EPDM. Optimization of the reaction conditions was carried: homogeneous (TBACl) and heterogeneous (TiO2) catalysts were efficient for the preparation of hydroxy-ester, and sulfonic resins in ether and the esterification of residual hydroxyls. A wide variety of reagents selected according to desired application were used. The derivative cyclohexanoate / acetate rapeseed methyl esters present the best plasticizing properties for PVC but it is unfortunately not bio-resistant. Ether-ester derivatives are not stable thermally and do not allow the plasticization of EPDM. A relatively non-polar di-unsaturated derivative (oleyl oleate) was synthesized for the plasticization and cross linking of EPDM. Several reactions are considered to link the oil and the polymer (hydrosilylation, ene- reaction and metathesis), but the reactivity is too low to allow the cross linking

The synthesis of materials with molecular recognition properties has become a topic of great technological and scientific interest. Molecular imprinting is one of the most effective strategies in preparing highly selective synthetic receptors. The technique of molecular imprinting involves the copolymerization of functional and cross-linking monomers in the presence of a molecular template. Following polymerization and subsequent removal of the template, the molecularly imprinted polymer (MIP) retains a “molecular memory” of the template. During rebinding, the resultant polymer shows higher affinity and selectivity towards the molecular template when compared to other structural analogs. Ease of preparation and high thermal and chemical stability of this class of materials offers a broad range of potential applications. Promising areas of application include separation, chromatography, catalysis, sensors, antibody mimics, and drug delivery etc. The thesis entitled “Molecularly Imprinted Polymers based on Fluorescent and Template binding Cross-linker” deals with the design and synthesis of several molecularly imprinted polymers (MIPs) using different functional and cross-linking monomers, the main focus being use of preformed template-monomer complex, use of fluorescent cross-linker and development of functional group containing cross-linker. Chapter 1: An Introduction to Molecularly Imprinted Polymers. The first chapter provides an introduction to the field of molecularly imprinted polymers. It presents an overview of molecular imprinting process including a brief history of its discovery and its evolution to the present form. This chapter further elaborates on the principle of molecular imprinting with an emphasis on different parameters that directly affect their performance. It also provides a brief review of the applications of molecularly imprinted polymers. Chapter 2: Highly Cross-linked Metal Ion Imprinted Polymers. The second chapter deals with the synthesis of series of highly cross-linked metal-ion imprinted polymers. The process of metal ion-imprinting usually involves carrying out the polymerization and cross-linking directly in presence of the appropriate metal ion. In the present study, chemical-immobilization method was adopted which involves the use of preformed metal complexes with polymerizable group for the imprinting. Acrylate complexes of various metal-ions, such as Cu2+, Zn2+, Co2+, Ni2+, Pb2+ and Cr3+, were synthesized prior to polymerization. These pre-assembled complexes were then used to prepare MIPs, in the anticipation that this would lead to enhanced selectivity. Ethyleneglycol dimethacrylate (EGDMA) was used as the cross-linking monomer. As a control, the respective non-imprinted polymers (NIPs) were also made in absence of the template metal ion. Following polymerization, the template metal ion was extracted from the resultant metal ion-imprinted polymer. The selectivity of the metal ion-imprinted polymers was examined by a batch process using analytical tools, such as, Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Spectroscopy (ICP). The spectroscopic studies revealed significant selectivity of all the MIPs towards the template metal ion. Among all six metal ion-imprinted polymers, Pb2+ and Cr3+ ion-imprinted polymer showed remarkable selectivity, followed by Cu2+ and Zn2+ ion-imprinted polymers. The Co2+ and Ni2+ ion-imprinted polymers exhibited comparatively poor selectivity. Representative plots depicting the selectivity exhibited by Pb2+ and Cr3+ ion-imprinted polymers are shown in Figure 1. These observations were rationalized based on the size and geometric preferences imposed by the imprinted site on the ion that binds to it. Figure 1. Selectivity study for (a) Pb2+ ion-imprinted polymer, (b) Cr3+ ion-imprinted polymer. Chapter 3. Molecularly Imprinted Fluorescent Chemosensor for Copper (II). Cu(II) is a source of important pollutant and therefore, the development of sensors that can detect Cu(II) selectively as well as remove Cu(II) from contaminated samples is an important objective. The use of molecular imprinting technique is an appealing approach in this regard. For this, a fluorophore containing cross-linker, namely 9,10-bis-(acryloyloxymethyl)anthracene (BAMA) was synthesized. This fluorescent cross-linker was used along with the standard cross-linker, EGDMA, for preparing Cu2+ ion-imprinted polymer. The complex of copper methacrylate (Cu-MAA) was prepared prior to polymerization used for the preparation of MIP. The resultant imprinted polymer exhibited quenching of the fluorescence in presence of Cu2+ ion, both in organic and aqueous medium. The efficiency of quenching of NIP (prepared in absence of Cu2+ ion) was significantly lower than that of MIP. A typical stack spectra showing the quenching process, along with a comparison of the quenching efficiency of MIP and NIP is shown in Figure 2. The imprinted polymers showed significant selectivity over other non-template metal ions, thereby reaffirming the importance of the imprinting process. The sensitivity of the fluorescence detection could be enhanced by increasing the level of the fluorophore incorporation. The increased sensitivity in detecting Cu2+ ion, demonstrated by the MIP suggests that a statistically random incorporation of the fluorophore into MIP matrices could be a useful approach for imparting a sensing element to MIPs. Figure 2. Fluorescence spectra of the (a) imprinted (MIP-1) and (b) non-imprinted (NIP-1) polymers in the presence of various concentration of Cu(OAc)2 in methanol. (c) Comparison of quenching efficiency of MIP-1 and NIP-1. Data were collected 3 h after addition of copper solution. I0 and I are the fluorescence intensities at 399 nm of the polymers in the absence presence of copper respectively. Two individual runs are presented in (c). Chapter 4. Molecularly Imprinted Turn-Off-On Sensor. This chapter describes the design and synthesis of molecularly imprinted fluorescent turn-off-on sensor utilizing the same fluorescent cross-linker, BAMA. Combining the process of fluorescence resonance energy transfer (FRET) with molecular imprinting technique, a novel turn-off-on sensor was developed. A molecularly imprinted polymer was prepared using a fluorescent template Coumarin-30 (C-30). C-30 was chosen as the template to ensure a significant overlap of the emission spectra of BAMA and the absorption spectra of C-30, thereby optimizing for FRET. Figure 3. Structures of relevant molecules. The C-30 imprinted polymer exhibited simultaneous quenching in fluorescence (turn-off) of BAMA and enhancement in fluorescence (turn-on) of C-30 (Figure 4). The imprinted polymer showed significantly better performance over the non-imprinted polymer (NIP). Figure 4. Fluorescence spectra of the (a) imprinted (MIP) and (b) non-imprinted (NIP) polymers with increasing concentration of the template Coumarine-30 in methanol. The UV-vis studies revealed that the more effective quenching is indeed due to the affinity for C-30 exhibited by the higher binding imprinted polymer. The imprinted polymer also showed significant selectivity over structurally analogous molecules. Therefore, both high sensitivity and selectivity were realized in such novel off-on sensor. Extension of this concept to other biologically relevant fluorescent templates could lead to potentially useful applications. Chapter 5. Design of New Template Binding Cross-linker. In molecularly imprinted polymers (MIP), high cross-linking density (~80 to 90 mole percent) is essential to ensure high selectivity, which limits the functional (binding) monomer to about 10-20 mole percent. Methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) are the most common combination of functional monomer and cross-linker, respectively, used in molecular imprinting. Generally a molecularly imprinted polymer made with this combination, contains only 10-20% binding sites. This limitation of binding site density is an aspect that has largely been overlooked. In order to improve the efficiency of MIP materials by enhancing the number of binding sites, a new cross-linking monomer (CYDI, 1) with two carboxylic acid groups was designed and synthesized by coupling itaconic anhydride with cyclohexane dimethanol (Figure 5). Figure 5. Structures of relevant molecules. The new functional group bearing cross-linking monomer (1) Itaconate ester of cyclohexanedimethanol (CYDI), the template (2) theophylline (Theop) and the structural analogue of template (3) caffeine (Caff). This new cross-linking monomer was then employed for preparing molecularly imprinted polymer using a drug molecule, theophylline (Theop 2, a bronchodilator) as the template. Seven molecularly imprinted polymers were synthesized with different ratios of CYDI and EGDMA, keeping the cross-linking density constant. The binding efficiency and the selectivity of these imprinted polymers were thoroughly investigated. It was seen that while saturation binding values for theophylline increased continuously with functional cross-linker (CYDI) content, the optimum selectivity with respect to analogous substrate, caffeine, was attained at 40 mol% CYDI. These studies suggest that the approach of using functional group containing cross-linkers could lead to improved MIP performance.

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Biodegradabilné syntetické polyméry nesú vlastnosti, ktoré ich zvýhodňujú oproti iným materiálom používaným na poli regeneratívnej medicíny a tkanivového inžinierstva. Najdôležitejšie výhody zahŕňajú schopnosť prispôsobovať mechanické a chemické vlastnosti aj kinetiku degradácie. Obzvlášť polyestery sú zaujímavé z pohľadu na ich biodegradáciu. Podliehajú hydrolýze, počas ktorej dochádza k štiepeniu esterových väzieb a degradačné produkty sú metabolizované bez akýchkoľvek škodlivých účinkov. Diplomová práca je zameraná na syntetické biodegradabilné triblokové kopolyméry PLGA-PEG-PLGA s obsahom kyseliny polymliečnej (PLA), kyseliny polyglykolovej (PGA) a polyetylénglykolu (PEG), ktoré patria do skupiny biodegradabilných polyesterov. Obsah hydrofilnej a hydrofóbnej zložky polymérneho reťazca spôsobuje amfifilný charakter kopolyméru. Pripravené triblokové kopolyméry sú schopné tvoriť hydrogél pomocou fyzikálneho sieťovania v dôsledku ich amfifilného charakteru. Tieto materiály zaznamenali významný záujem vo vedeckej oblasti. Teoretická časť diplomovej práce všeobecne popisuje hydrogély, bližšie sa venuje fyzikálnemu sieťovaniu amfifilných blokových kopolymérov a mechanizmom degradácie. Podrobný popis triblokového kopolyméru PLGA-PEG-PLGA je rozdelený na PLGA kopolyméry, PEG a ich fyzikálno-chemické vlastnosti. Zahrnuté sú aj poznatky o chemickej funkcionalizácii anhydridom kyseliny jantárovej, anhydridom kyseliny itakonovej a kyselinou listovou. Dopamín je prezentovaný ako spájací faktor a spomenuté sú taktiež najdôležitejšie bioaktívne látky. Experimentálna časť sa zaoberá konkrétnymi metódami syntézy, ktoré viedli k funkcionalizácii a modifikácii triblokových kopolymérov PLGA-PEG-PLGA. Funkcionalizáciou anhydridom kyseliny itakonovej bol získaný kopolymér s oboma koncami obohatenými o reaktívne dvojité väzby a karboxylové funkčné skupiny. Dvojité väzby umožňujú chemické sieťovanie a koncové karboxylové skupiny ponúkajú možnosť modifikácie kopolyméru biologicky aktívnymi látkami. Modifikácia bioaktívnymi látkami L-lyzínom a butylamínom obohacuje polymérnu sieť a dopamín v roli spojovacieho faktoru poskytuje univerzálnosť v naväzovaní bioaktívnych látok, stabilizuje ich a zabezpečuje zachovanie biologickej aktivity naviazaných bioaktívnych látok predĺžením reťazca. Výsledné produkty boli charakterizované pomocou 1H NMR, FTIR a DRA analýz. Funkcionalizácia anhydridom kyseliny itakonovej bola prevádzaná v tavenine. Podarilo sa dosiahnuť vyššieho množstva naviazanej kyseliny itakovovej s hodnotou 79,4 mol % a následné modifikácie boli prevádzané vo vodnom roztoku, organickom roztoku a taktiež v tavenine. Bolo zistené, že najefektívnejšia metóda modifikácie bola syntéza v organickom roztoku s rozpúšťadlom N,N-dimetylformamidom a aktivačným systémom dicyklohexylkarbodiimid/4-(dimetylamino)pyridínom. Najvyššie množstvo naviazaného dopamínu bolo 18,6 mol %, najvyššie množstvo naviazaného butylamínu bolo 7,8 mol % a L-lyzín sa naviazať nepodarilo.

Le cross-linking du collagène cornéen (CXL) est une cornéoplastie mini-invasive reposant surun concept biomécanique difficile à objectiver physiquement et dont les preuves del’efficacité thérapeutique sont d’interprétation complexe. Les principes, les nuances et lesrésultats du CXL sont colligés dans cette thèse afin de valider l’intérêt du modèleexpérimental choisi pour tester la pertinence de notre travail de recherche sur l’élastographiecornéenne par ondes de cisaillement.Notre cheminement expérimental a abouti au choix du modèle de CXL trans-épithélial (TCXL)assisté par iontophorèse (I-CXL), réalisé in vivo, sur oeil de lapin. Les mesuresélastographiques obtenues après euthanasie ont ainsi pu démontrer une modificationsignificative du profil d’élasticité de la cornée après CXL, testé successivement de manièredynamique et statique.Nos résultats confirment donc l’efficacité biomécanique instantanée du I-CXL et donnent uneidée plus précise de la valeur de la photo-polymérisation du tissu cornéen isolée desphénomènes liés à la cicatrisation. Les enjeux technologiques de l’élastographe cornéen paranalyse des ondes de cisaillement ont pu être définis afin de développer une stratégie de miseen oeuvre d’un système pertinent pour la pratique clinique. / Corneal collagen cross-linking (CXL) is a kind of minimaly invasive corneoplasty mainlybased on a biomechanical concept, which is very difficult to measure physically, and whichthe therapeutic efficacy understanding is complex.Principles, different protocols and resultsare summarized in this thesis in order to illustrate the usefulness of the experimental modelchosen in our experimentations about elastographic corneal shear wave imaging.The pathway of our experimental work have led to the choice of trans-epithelial CXL (TCXL)assisted by iontophoresis (I-CXL), performed in vivo, on rabbits eyes. Elastographicmeasurements we obtained after animals euthanasia have shown a significant change of thecorneal elasticity profile after CXL, successively tested in a dynamic and in a static fashion.Our results do confirm the biomechanical efficacy of the I-CXL procedure and give a moreprecise idea of the sole photo-polymerization effect by avoiding any confounding healingconcern. Technological issues for corneal elastography with shear wave imaging have beenraised in this thesis to develop a realistic strategy for the launch of a clinically useful device.

Der Einfluss von reduzierten Dimensionen und zunehmendem Vernetzungsgrad auf die Polymerkettendynamik in der Nähe der Glassübergangstemperatur, Tg, wird mittels der Vibrating Reed Technik untersucht. Die mechanische Dämpfung der unterstützten Polymerfilme, wird am System Polymerfilm/Substrat gemessen. Mechanische Spektroskopie liefert nicht nur die Information über Tg, es können auch die ganzen Relaxationsspektren untersucht werden.Der Effekt der reduzierten Dimensionen wird an PS Filmen untersucht. Für Filmdicken unterhalb 100 nm, wird der α Relaxationspeak, der mit dem Glassübergang verknüpft ist, zu kleineren Temperaturen hin verschoben und verbreitert. Dieser Effekt wird nur bis zu 44 nm Filmdicke beobachtet. Ein Model, das dises Verhalten beschreibt, wird vorgeschlagen. An der Grenzfläche Vakuum/Film existiert eine flüssigskeitsähnliche Schicht, die eine erhöhte Kettenbeweglichkeit zeigt, was zu dem Abfall von Tg führt. Bei der mechanischen Spektroskopie ist das Verhalten der Schicht viskos und zeigt keinen Glassübergang in dem gemessenen Temperaturbereich. Folglich, würde sich im Falle, dass die Filmdicke gleich der Dicke der flüssigkeitsänlichen Schicht ist, Tg gegen 0 annähren. Der Gegeneffekt wird durch die erhöhte Dichte an der Film/Substrat Grenzfläche untersucht, die durch die bevorzugte out of plane Orientierung den Phenylringe entsteht.Der Einfluss der Vernetzung auf die Dynamik bei Bulkfilmen wird an dem Beispiel von Poly(vinyl cinnamate) (PVCN) untersucht. Das Material ist vernetzbar durch die Bestrahlung mit UV Licht. Der Vernetzungsgrad wird durch die IR Spektroskopie untersucht. Die Beweglichkeit in der vernetzten Struktur ist behindert, deshalb wird der α Relaxationspeak zu größeren Temperaturen verschoben und die Relaxationsstärke nimmt ab. Die Linienbreite ist beeinflusst durch die Verbreiterung der Relaxationszeitdistribution, die im Folge der neuen heterogenen Struktur auftritt. Der Anteil der Vernetzungsknoten für PVCN beträgt etwa 75%.