Ce travail de thèse a été réalisé, dans le cadre de la convention CIFRE 1538/2010, au sein d'adixen Vacuum Products (aVP) à Annecy (France). Il a été en partie financé par le projet S.P.A.M. (Surface Physics for Advanced Manufacturing). Il s'agit d'un projet ITN financé par le programme Pierre et Marie Curie de la Communauté Européenne rassemblant des partenaires universitaires et industriels dont aVP. L'objectif de ce programme était de contribuer à l'étude et au développement de la lithographie et en particulier la lithographie à ultraviolet extrême (EUVL). Ce travail porte sur la problématique de la contamination moléculaire dans l'industrie des semi-conducteurs ainsi que les besoins de maitrise de contamination pour la photolithographie EUVL. Pour ce faire, des modèles mathématiques de sorption ont été recherchés, testés et validés à l'aide d'une microbalance à quartz (QCM). Cette technique, possédant une très haute sensibilité (au niveau du ng), permet d'étudier les phénomènes de sorption relatifs à tout matériau déposable sur un cristal de quartz mis au contact de différents gaz dont la pression partielle est maitrisée. Par conséquent, le protocole détaillé dans cette thèse peut être utilisé pour d'autres types d'expériences dans toute discipline nécessitant une telle précision. Le déroulement de notre plan d'expérience comprend deux types de matériaux naturellement différents : un polymère (PCBA) d'une part et deux substrats métalliques (SS AISI 304 et CuC1) d'autre part pour lesquels le transfert de masse n'intervient pas de la même manière. Les gaz d'étude ont été sélectionnés pour leur intérêt dans l'industrie des semi-conducteurs (vapeur d'eau, HF). Le résultat de l'interaction des gaz d'étude avec les substrats ciblés est suivi en direct par la QCM, ce qui permet non seulement de valider et/ou améliorer les modèles mathématiques déjà disponibles dans la bibliographie mais aussi de les ajuster aux données obtenues expérimentalement. Nous pouvons ainsi non seulement prévoir le comportement des contaminants à l'équilibre (isothermes) et à l'état transitoire mais aussi réaliser des estimations de sorption à des températures autres que celles retenues pour notre plan d'expérience / This thesis was carried out within the framework of the CIFRE 1538/2010 convention at adixen Vacuum Products (aVP) in Annecy (France). It is has been partly funded by the ITN project SPAM (Surface Physics for Advanced Manufacturing). SPAM is an ITN project funded by the Pierre and Marie Curie program of the European Community bringing together academic institutions and industrial partners including aVP. The objective of this program was to contribute to the study and development of lithography and extreme ultraviolet lithography (EUVL). This work deals with the issues caused by the airborne molecular contamination (AMC) in the semiconductor industry and their control needs in EUVL and the current photolithography. In order to tackle the problem, sorption mathematical models have been investigated and validated using a quartz crystal microbalance (QCM). This technique, which confers a high sensitivity (ng level), allows the study of the sorption phenomena related to any deposable material onto a quartz crystal in contact with different gases whose concentrations are accurately controlled. Consequently, the protocol detailed in this thesis may be used for other types of experiments in any discipline requiring such precision. The conduct of our experimental plan includes two types of naturally different materials: a polymer (PCBA) on the one hand and two metallic substrates (stainless steel AISI 304 and CuC1) on the other hand, for which the matter transfer does not occur in the same manner. Studied gases were selected for their interest in the semiconductor industry (water vapor, HF). The resulting interaction between the studied gases and the targeted substrates is continuously followed by the QCM, which allows not only to validate the mathematical models already proposed by the literature but also to fit the experimentally obtained data. This enables us not only to predict the behavior of the AMC at equilibrium (isotherms) and the transient state but also to provide sorption estimations at temperatures other than those specified in our experimental plan

L’objectif principal de ces travaux de thèse était de comprendre l’impact de la chimie de surface de NPs lors de leur interaction avec des interfaces biologiques. Deux sortes de NPs cœurs-coquilles ont été étudiées : des NPs sphériques de silice mésoporeuse Fe3O4@MSN de 100 nm de diamètre, contenant un cœur magnétique et des NPs composées d’analogues de bleu de Prusse (ABP) de formes cubiques (BP), cuboïdes (FeNi), ou polyédriques Au@BP contenant un cœur d’or, de tailles comprises entre 47 et 67 nm. Ces NPs différent par leur taille, leur composition chimique et leur forme. Les NPs de silice mésoporeuse, particulièrement étudiées ces dernières années pour leurs potentielles applications médicales, ont été choisies pour estimer la pertinence du recours à des modèles membranaires supportés pour l’évaluation de la sécurité biologique de nanomatériaux pour la santé. Les NPs Fe3O4@MSN ont été synthétisées de façon homogène et reproductible. Ces NPs ont ensuite été fonctionnalisées, par greffage de groupements PEG sur la silice, ou recouvertes avec une bicouche lipidique. L’influence des propriétés de surface sur la stabilité en suspension de ces NPs a été caractérisée dans différents milieux. Les effets de ces NPs sur la viabilité cellulaire et la cinétique d’internalisation ont été suivis sur une lignée cellulaire d’hépato-carcinome humain HepG2. Afin d’appréhender la relation entre les propriétés de surface des NPs et leurs effets sur les cellules, l’interaction des NPs avec des modèles membranaires a été étudiée. Les interactions des NPs avec des modèles membranaires ont été suivies par microbalance à quartz (QCM-D) et résonance plasmonique de surface (RPS). Les NPs fonctionnalisées sont plus rapidement internalisées que les NPs natives, en particulier les NPs recouvertes de bicouches lipidiques, mais sont moins toxiques pour les cellules HepG2. La présence de protéines de sérum de veau fœtal induit la formation d’une couronne de protéines qui influence l’interaction des NPs natives avec les membranes. Par contre, les groupements PEG ou le recouvrement lipidique forment un encombrement stérique limitant l’adhésion des protéines à la surface, qui n’influencent donc pas l’interaction des NPs avec les membranes. D’autre part, les NPs d’ABP ont été recouvertes avec des bicouches lipidiques. Les NPs polyédrique Au@BP contiennent un cœur d’or pour leur conférer des propriétés plasmoniques. La forme des NPs, sphériques, cubiques, cuboïdes ou polyédriques, n’influence pas le recouvrement lipidique. Ces différentes NPs, agrégées à 150 mM de NaCl, sont stabilisées en suspension par la formation d’une bicouche lipidique supportée en surface. L’influence de la forme sur la sécurité biologique des NPs peut ainsi être étudiée, celles-ci ayant des propriétés de surface communes mais différentes formes. / This work is a part of a multidisciplinary project focused on the safety of nanoparticles (NPs) developed for theranostic applications. The goal of this thesis is to investigate the role of surface chemistry of NPs at the biological interface. Two types of core-shell NPs have been studied: spherical mesoporous silica Fe3O4@MSN, with a diameter of 100 nm and a magnetic core, and cubic, cuboid and polyhedral NPs composed of Prussian blue analogous, presenting sizes comprised between 47 and 67 nm. The polyhedral Prussian blue NPs Au@BP contain a gold core. The NPs present different sizes, shapes and chemical compositions. Mesoporous silica NPs (MSN), particularly studied for their potential medical applications, have been used to evidence the relevance of model membranes to investigate NPs safety. First, Fe3O4@MSN were homogeneously synthesized, in reproducible 100 mg batches. These NPs have been functionalized by PEG grafting and lipid coating. The influence of the surface properties on the NPs stability have been characterized in various media. A human hepatocarcinoma cell line HepG2 have been used to measure the cell viability and observe the uptake kinetics when the cells are incubated with Fe3O4@MSN. To rely the surface properties of the NPs to their cell effects, the interaction of NPs with membrane models have been studied. Quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (RPS) were used to follow NPs-model membrane interactions. Functionalized NPs were uptaken faster than the bare ones, in particular lipid coated NPs, but were less cytotoxic for HepG2 cells. The presence of fetal calf serum proteins reduces the interaction of bare Fe3O4@MSN with model membranes, due to the protein corona that formed around the NPs. However, the presence of proteins doesn’t change NPs-model membranes interactions when NPs are functionalized by PEG grafting or coated with a lipid bilayer. The PEG groups and the lipid bilayers constitute a steric barrier which reduces the protein adhesion at the NPs surfaces. On the other hand, Prussian blue analogous NPs were also coated with lipid bilayers. The golden core of the polyhedral one’s confers localized plasmon properties. The lipid bilayer coating is equally performed on spherical, cubic, cuboid or polyhedral shapes of the various NPs. These different NPs are aggregated in high ionic strength conditions, with 150 mM NaCl, but dispersed when coated by lipid bilayer. The influence of the shape on the safety of the NPs may be compared, using these NPs with common surface coating but various shapes.

Functionalized membranes provide an elegant platform for selective separations and sorptions. In this dissertation, application of functionalized membranes for surfactant and metal sorption studies are discussed. Sorption behavior of surfactants is also studied using quartz crystal microbalance (QCM) and other techniques. Adsorption of the ethoxylated surfactants on polymeric materials (cotton and polyester) and model gold surface was quantified from a non-aqueous siloxane based solvent (D5) and water. The role of ethylene oxide group and the effect of nature of polymeric materials on adsorption behavior was quantified and established. In the case of gold-water interface, the adsorption data was fitted to calculate adsorption/desorption rate constants. The study is important towards applications involving use of the surfactants in cleaning operations. PAA functionalized membranes were prepared and used for separation of the surfactants from the siloxane solvent. Finally the pH sensitivity of the PAA-surfactant complex was verified by successful regeneration of the membrane on permeation of slightly alkaline water. The preparation and application of thiol and sulfonic acid functionalized silica mixed matrix membranes for aqueous phase metal ion sorption is also studied. The functionalized particles were used as the dispersed phase in the polysulfone or cellulose acetate polymer matrix. The effects of the silica properties such as particle size, specific surface area, and porous/nonporous morphology on the metal ion sorption capacity were studied. Silver and ferrous ions were studied for metal sorption capacities. The ferrous ions were further reduced to prepare membrane immobilized iron nanoparticles which are attractive for catalytic applications. One dimensional unsteady state model with overall volumetric mass transfer coefficient was developed to model the metal ion sorption using mixed matrix membrane. The study demonstrates successful application of the functionalized mixed matrix membranes for aqueous phase metal capture with high capacity at low transmembrane pressures. The technique can be easily extended to other applications by altering the functionalized groups on the silica particles. The study is important towards water treatment applications and preparation of membrane immobilized metal nanoparticles for catalytic applications.

A técnica de Microbalança de Cristal de Quartzo (QCM) tem sido utilizada para a aplicação em biossensores. Esta técnica consiste no monitoramento da freqüência de oscilação do cristal de quartzo e a variação de freqüência está relacionada com a variação de massa na superfície do cristal por meio da equação de Sauerbrey. Porém, sabe-se que há discrepância entre a massa calculada pela equação de Sauerbrey e a massa real aderida na superfície do cristal de quartzo, sendo tal discrepância causada por fatores tais como a viscoelasticidade, o que é especialmente observado para macromoléculas e sistemas biológicos. Com a técnica de Admitância Eletroacústica (AE) é possível analisar a massa real devido à análise em separado dos parâmetros que compõem o circuito equivalente do cristal de quartzo e também inferir informações sobre a estrutura das monocamadas montadas sobre a superfície do cristal de quartzo. Neste trabalho foi utilizada técnica de AE para se potencializar e detalhar o estudo da formação de monocamadas automontadas e interações entre diferentes proteínas e carboidratos. Em muitos casos verificou-se que durante a formação de determinadas monocamadas, grande parte da variação de massa estava relacionada a interações fracas e não-específicas. Também durante a formação das monocamadas de tióis de cistamina, verificou-se que a estrutura da monocamada é extremamente dependente das concentrações iniciais de cistamina utilizadas para formar a monocamada. As interações entre proteínas e carboidratos foram realizadas após formação de multicamadas nas quais as proteínas eram imobilizadas para depois estudar-se, então, sua interação com carboidratos específicos. No caso da Jacalina, um tipo de lectina, observou-se interações bastante específicas com a fetuína e interações fracas com a alfa-lactose. A atividade da enzima GumH também foi testada com sucesso utilizando a técnica de AE. / The Quartz Crystal Microbalance (QCM) has been largely used for biosensor applications. This technique consists on monitoring quartz crystal oscillation frequency. The relationship of quartz crystal frequency variation with mass deposited on the crystal surface is described by Sauerbrey´s equation. However, the relationship is not directly inferred and discrepancy exists caused mainly by viscoelasticity features of mass adsorbed on the quartz crystal surface. The viscoelastic influence is very common to be observed especially for macro-molecules and biological systems. By using Electroacoustic Admittance (EA) technique it is possible to calculate and separate the real mass deposited over the quartz crystal from other contributions. Therefore, the EA was used to infer about self-assembly monolayer structure being deposited over the quartz crystal. In this work EA technique was used to study details of self-assembled monolayer formation and specific interactions between different proteins and carbohydrate molecules. It was observed that during monolayer formation the majority of mass variation was related to non-specific interactions. For instance, regarding cystamine monolayer formation it was observed that the monolayer structure is dependent on the cystamine concentrations in the liquid medium. The study of interactions between proteins and carbohydrates was conducted by means of multilayers approach in which the proteins are immobilized previously to study the interaction between its active sites and carbohydrates. In the specific case of Jacalin, a type of lectin, it was observed a large formation of specific bonding between this protein and alpha-lactose or fetuin. The GumH enzyme activity was also tested successfully by using of EA technique.

A deposição em regime de subtensão (DRS) de cádmio e chumbo foi estudada sobre ouro e filmes de selênio em meio ácido. Os estudos foram realizados utilizando a voltametria cíclica (VC) e a microbalança eletroquímica de cristal de quartzo (MECQ). Foi observado que o cádmio e o chumbo se depositam de formas diferentes sobre ouro e sobre os filmes de selênio. O cádmio quando depositado sobre o eletrodo de ouro ocupa um átomo de ouro por ad-átomo, fornecendo uma carga associada à formação da monocamada adsorvida de aproximadamente 42 µC cm-2, que corresponde a um recobrimento de 0,15 monocamadas. Os resultados com a MECQ mostraram que a deposição em regime de subtensão do Cd ocorre com uma forte presença da adsorção de ânions perclorato e bissulfato. A DRS de cádmio sobre os filmes de selênio ocorre de maneira semelhante a que foi observada sobre o eletrodo de ouro, porém a carga total da monocamada adsorvida foi de 195,7 µC cm-2, que é um pouco maior do que a carga total para a formação de uma monocamada de selênio sobre ouro. Além disso, foi observado que o cádmio difunde no filme de selênio, e que a co-adsorção de ânions e água durante a formação da monocamada de cádmio foi negligenciável. O ad-átomo de chumbo ocupa dois átomos de ouro e a carga de formação da monocamada é atribuída a contribuições de dois picos relacionados com a DRS. O recobrimento máximo chega a 0,3 monocamadas de chumbo sobre ouro, com a deposição do tipo loosely packed. O processo de DRS sobre os filmes de selênio ocorre com a formação de um único pico. A formação do segundo pico sofre interferência da formação de H2Se que ocorre na superfície do filme de selênio e modifica o tipo de empacotamento dos ad-átomos de chumbo sobre o substrato eletródico. O recobrimento obtido com a DRS foi de 0,7 monocamadas de chumbo sobre selênio. A co-adsorção de ânions e água foi constante, tanto em estudos sobre o eletrodo de ouro, como sobre os filmes de selênio. O estudo das propriedades dos filmes de selênio modificados por ad-átomos de cádmio e chumbo foi efetuado por medidas de cronoamperometria para altos tempos de polarização. Foi observado que o cádmio difunde para a fase do filme de selênio, em função do seu alto coeficiente de difusão no estado sólido, formando o composto CdSe. Por outro lado, este processo de difusão não foi observado para o chumbo, não havendo evidências de formação do composto PbSe. A combinação da voltametria cíclica com a microbalança eletroquímica de cristal de quartzo possibilitou acompanhar as mudanças nos mecanismos de formação de monocamadas de cádmio e chumbo em potenciais de subtensão, assim como a inibição da formação do H2Se. Este último efeito foi marcante na DRS de chumbo, onde foi alterada a forma de empacotamento do ad-átomo na superfície. / Cd and Pb underpotential deposition (UPD) on gold electrode and selenium thin film, from acid media, were studied using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). Different form of deposition for cadmium and lead were observed on gold electrode and selenium thin film. The presence of one peak in the positive sweep with a total charge density value between 42 60 µC cm-2 was observed from the results obtained for Cd upd on Au. This result is attributed to a covering of 0.15 0.20 Cd monolayer on gold electrode with the occupation of one active site by each Cd ad-atom. EQCM results suggest a large increase in mass upon Cd upd, which appears to result from co-adsorbed perchlorate and bisulfate anions. The upd of cadmium on the selenium films were similar to the observed on the gold electrode; however with a higher associated charge of 196 µC cm-2. Moreover, the cadmium upd process on selenium is accompanied by the diffusion of cadmium into the bulk of Selenium films. Also, the co-adsorption of anions and water during cadmium deposition on Selenium films were negligenceable. The UPD process of Pb ad-atoms on gold electrodes occurs with the occupation of two gold atoms for ad-atom ones. Two electrochemical processes are observed and the charge values were conferred a low covering the 0.3 monolayer, with a wrapping up of the type loosely packed. The co-adsorption of perchlorate anions and water were observed during UPD process. The UPD process of Pb ad-atoms on the selenium films is complex, and the formation of H2Se modifies the type of wrapping up of lead ad-atoms on the electrode surface. In this case, that the gotten covering were 0.7 monolayer of lead on selenium, were observed the co-adsorption of anions and water in this UPD process. During the studies carried through for cronoamperometry in high times of polarization (UPD potentials) on the Se films were observed that the cadmium spreads out for the phase of the selenium film. This phenomenon occurs due to the high coefficient of diffusion in the solid state of the Cd, allowing the formation of the CdSe. On the other hand, this process of diffusion was not so evident for the lead, that presents a low coefficient of diffusion in the solid state, and thus, do not support the formation of PbSe. The UPD studies by cyclic voltammetry combined with electrochemical quartz crystal microbalance measurements allowed to observe the changes in the monolayers formation mechanisms of cadmium and lead, as well as the inhibition of H2Se formation. This effect was found in the lead UPD, where was modified the form of packing up of the adatom in the surface.

Abstract This thesis describes the design, fabrication and operation of a microfluidic device for the screening of biomolecule mixture surface mediated effects. The characterisation of a surface immobilisation strategy that will allow the robust attachment of candidate biomolecules on a substrate for use in cell culture applications. This is carried out in the form of a modified and optimised layer-by-layer surface immobilisation strategy and its subsequent thorough and robust characterisation. This was achieved by compiling and critically analysing large amounts of quartz crystal microbalance with dissipation (QCM-D) data and the model utilised to provide meaningful, physical data as an output. QCM-D data was combined with surface plasmon resonance (SPR) data to validate the assumptions used within the QCM-D model package. Further evidence demonstrating the presence of the multilayer, as described by QCM-D and SPR, is achieved using x-ray photoelectron spectroscopy (XPS). These results show that the multilayer surface is robustly attached to the substrate and consists of a large amount of water whilst being able to immobilise mixtures of four proteins. A custom protocol for fabricating these two layer devices was devised and is presented. Scale limitations have been overcome to provide mixing capabilities for large extracellular matrix molecules to be immobilised on the previously described, microfluidically generated surface immobilisation strategy. The optimisation and characterisation of the mixing within this microfluidic device, affected by the incorporated staggered herring bone mixer is also shown. Using dynamic force spectroscopy (DFS) along with a custom designed force curve data processing and analysis package, the spatial localisation of a mixture of four immobilised biomolecules was determined. The aim of this study was to compare the spatial localization of a mixture of four biomolecules created by; standard cell culture protocols (adsorbed from bulk onto tissue culture polystyrene) and a surface created via microfluidic deposition on top of a previously described surface immobilisation strategy. The design and robust application of this custom analysis package allows the definition of a “Barricade of Specificity” such that interactions between an antibody functionalised AFM tip and a surface composed of a mixture of proteins, to be categorised as either a “true” specific interaction, or a non-specific interaction. The application of this Barricade of Specificity thus allows the spatial localisation of four immobilized biomolecules to be determined with a large degree of accuracy as a result of the large rage of non-specific interactions surveyed and the strict definition of a valid rupture force. The final chapter details the application of the microfluidic platform to enable high throughput screening of the effects of extracellular matrix (ECM) molecules, singly and in combination, with regards to the effect on the expression of cell surface markers on umbilical cord blood (UCB) derived CD34+ cells. Careful selection of candidate ECM molecules, cytokine and oxygen concentration has resulted in little difference in the effect on UCB derived CD34+ cells differentiation state after seven days in culture. The major effect has been the maturation towards lymphocyte and leukocyte precursors. However, of the four ECM molecules tested individually, in binary and in quaternary combinations, osteopontin (Opn) and laminin (Ln) demonstrated differences compared to other surfaces tested. In order to further assess the effect of these protein surfaces on the cell surface marker expression of UCB derived CD34+ cells, further tests are warranted for increased periods of time to enable greater discrimination in marker expression and thus increase our understanding of the fundamental biology of this rare and clinically useful cell source.

Ce travail consiste en l'étude et la réalisation d'un micro-capteur destiné à la mesure de concentration d'un composé en solution. La méthode de détection est basée sur la variation de fréquence de résonance d'un micro-dispositif mécanique dont la surface est fonctionnalisée pour adsorber le composé à mesurer. Ces biocapteurs en silicium, sous forme de micromembranes piézoélectriques, sont remarquables par leur grande sensibilité et la possibilité d'explorer en parallèle de nombreux échantillons. Après avoir exposé les différentes technologies de biocapteurs existantes, l'étude se concentre sur l'optimisation des conditions d'élaboration de couches minces piézoélectriques pour obtenir un procédé technologique parfaitement compatible avec la technologie silicium. Une caractérisation mécanique de ces membranes a été effectuée par interférométrie optique 3D pour extraire le coefficient piézoélectrique du matériau. Les premières membranes réalisées présentent des propriétés d'actionnement excellentes. Une deuxième génération de membranes a ensuite été réalisée en modifiant les géométries des différentes couches. La sensibilité obtenue est compatible avec les seuils de détection nécessaires pour la détection de molécules biologiques. Des protocoles chimiques permettant la fonctionnalisation de la surface des micromembranes ont ensuite été développés. L'évaluation du comportement du microdispositif en situation, c'est-à-dire en milieu liquide, a enfin été effectuée. Pour cela, une cellule fluidique avec régulation de température a été mise au point. Les membranes piézoélectriques ont été positionnées à l'intérieur de cette cellule fluidique pour mesurer la cinétique d'adsorption de nanoparticules d'or en solution. Dans le cadre des biopuces, des microleviers permettant le dépôt de micro-gouttes de solutions ont aussi été développés. Ils permettent notamment de fonctionnaliser individuellement chaque membrane et présentent l'avantage de ne pas endommager les microstructures.

Le nano-moteur qui se trouve à la base des flagelles des bactéries est une merveille de part sa structure et son rôle dans la survie des bactéries. Il permet la mise en rotation rapide (300Hz) d'un long filament à l'extérieur de la bactérie, filament qui va jouer un rôle comparable à une hélice de sous marin. Malgré sa taille, 45 nm dans son plus grand diamètre, cette nano-bio-machine est composée de milliers de protéines, briques essentielles à la vie. Ces protéines travaillent de concert afin de faire tourner le flagelle bactérien et permettre à la bactérie de se mouvoir dans son environnement au gré du milieu dans lequel elle évolue. Malgré son importance dans la vie bactérienne, son fonctionnement précis reste encore relativement flou aujourd'hui. Sa découverte il y a plus de 30 ans a permis l'accumulation de données qui permettent d'esquisser la structure de certaines des protéines, leur emplacement ou le rôle joue par certaines parties de ces mêmes protéines. D'autres expériences ont permis de déduire des caractéristiques mécaniques, comme les relations couple/vitesse de ce moteur. Cependant, sa description à l'échelle nanométrique reste a ce jour limité et sujette à précautions. Dans le cadre de ma thèse, deux approches parallèles et complémentaires ont été développé afin de répondre à ce défi : le réassemblage de manière contrôlé in vitro d'une partie du moteur crucial pour le fonctionnement du moteur, l'étude à grande échelle des interactions entre les protéines identifiées comme étant essentielles à la rotation du flagelle. De nombreux outils qui n'avaient jamais été utilisés pour l'étude du moteur ont été mis à profit : le microscope à force atomique, afin de visualiser dans un environnement proche du milieu natif les parties du moteur réassemblées, et la Micro Balance à Quartz pour les études d'interactions. Des nouvelles données ont pu être obtenues et synthétisées dans une nouvelle hypothèse de fonctionnement du Nano-moteur flagellaire des bactéries q ui sera présentée.

L'objectif de la thèse est de réaliser des dispositifs électrochromes flexibles à signature infrarouge contrôlable dont les propriétés électro-optiques sont conférées par un polymère conducteur. En effet, l'application d'une différence de potentiel entre deux électrodes, dont l'une est le polymère conducteur, doit permettre de moduler la signature infrarouge du dispositif en bande II (3-5 µm) et III (8-12 µm), par modifications réversibles des propriétés optiques du polymère conducteur. <br /><br />La couche mince de polymère conducteur est électrochimiquement déposée sur une membrane microporeuse dorée, réflectrice vis à vis du rayonnement incident. Le polymère conducteur passant d'un état optique transparent à absorbant lors du processus électrochimique de dopage-dédopage engendre alors le contraste. Deux polymères conducteurs ont été étudiés : la polydiphénylamine et le poly(3,4-éthylènedioxythiophène). <br /><br />Le cyclage électrochimique des couches minces de polymères conducteurs met en évidence des effets de gonflement réversibles qui dépendent principalement de la nature du dopant et de l'électrolyte de cyclage. L'analyse de l'impédance d'une microbalance à quartz électrochimique, sur lequel est déposé le polymère, a permis de suivre in situ les changements de masse et de morphologie du film pendant les cycles d'oxydoréduction. Les insertions et les désinsertions des différentes espèces chimiques (ions et molécules de solvant) lors des processus redox ont ainsi pu être quantifiées. L'influence de la nature du dopant, l'effet de la nature de l'électrolyte de cyclage, ainsi que le type de signal électrique appliqué (triangulaire ou carré) ont été étudiés.<br /><br />Des dispositifs électrochromes flexibles à base de membranes poreuses et de polymères conducteurs ont été assemblés. Nous avons pu alors montrer que le contraste réversible obtenu dans le moyen infrarouge était lié aux mouvements d'insertion et de désinsertion des espèces chimiques mis en évidence à l'aide de la microbalance à quartz.

This thesis concerns the development of surface ligation techniques for the preparation of carbohydrate biosensors. Several methodologies were developed based on efficient photochemical insertion reactions which quickly functionalize polymeric materials, with either carbohydrates or functional groups such as alkynes or alkenes. The alkyne/alkene surfaces were then treated with carbohydrate azides or thiols and reacted under chemoselective Cu-catalyzed azide-alkyne cycloaddition (CuAAC) or photo-radical thiol-ene/yne click chemistry, thus creating a range of carbohydrate biosensor surfaces under ambient conditions. The methodologies were evaluated by quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) flow through instrumentations with recurring injections of a range of lectins, allowing for real-time analysis of the surface interactions. The developed methods were proven robust and versatile, and the generated carbohydrate biosensors showed high specificities and good capacities for lectin binding.  The methods were then used to investigate how varying the glycan linker length and/or a sulfur-linkage affect the subsequent protein binding. The survey was further explored by investigating the impact of sulfur in glycosidic linkages on protein binding, through competition assays with various O/S-linked disaccharides in solution interactions with lectins. / QC 20120309