Surface plasmon microscopes are mostly built around the prism based Kretschmann configuration. In these systems, an image of a sample can be obtained in terms of an intensity map, where the intensity of the image is dependent on the coupling of the light into the surface plasmons. Unfortunately the lateral resolution of these systems relies on the ability of plasmons to propagate along the metallised layer and is usually limited to a few microns unless special measures are taken. The widefield surface plasmon microscope (WSPR), used here enables surface plasmon imaging at significantly higher lateral resolutions than prism based systems. In this study we demonstrate the functionality of the WSPR by imaging a sequence of binding events between micro-patterned extracellular matrix proteins and their specific antibodies. Using the WSPR system a change in contrast was observed with each binding event. Images produced via the WSPR system were analyzed and compared qualitatively and quantitatively. Consequently, we confirm that the WSPR microscope described here can be used to study sequential monomolecular layer binding events on a micron scale. These results have significant implications in the development of new micron scale bioassays.

This thesis provides a compendium for the use of microcontact printing in fabricating electrical devices. Work has been undertaken to examine the use of soft lithographic techniques for employment in electronic manufacture. This thesis focusses on the use of high electric field generators as a means to producing electroluminescent devices. These devices provide a quantifiable output in the form of light. Analysis of the electrical performance of electrode structures can be determined by their success at producing light. A prospective reduction in driving voltage would deem these devices more efficient, longer lasting and an improvement on current specification. The work focussed on the viability of using relatively crude print techniques to create high resolution structures. This was carried out successfully and demonstrated that lighting structures of 75 μm and 25 μm have been produced. Microcontact printing has been established as a method for patterning gold surfaces with a functionalising self-assembled monolayer using alkanethiol molecules. This layer is then utilised as an etch resist layer to expose gold tracks for use as electric field generator electrode arrays. Through careful analysis of each step of the printing process, techniques were developed and reported to create a robust and repeatable print mechanism for reliability and accuracy. These techniques were employed to optimise the print process culminating in the development of each stage and final electrode structures mounted on a rigid backplate for use as electroluminescent devices for characterisation. These devices were then modelled for their electrical characteristics and investigated for being used in low voltage application. In this case for the development of electroluminescent applications, a driving voltage of 65 V was achieved and represents a significant advance to the field of printed electronics and Electroluminescence.

A non-crosslinking approach that covalently bonds nitroxide polymer brushes onto the ITO substrates via surface-initiated atom transfer radical polymerization (ATRP) was develpoed. Since the indium tin oxide (ITO)-silane covalent bonding providesvery strong chemical bonds to adsorb the nitroxide polymer brushes on ITO, it prevents polymers from dissolving into electrolyte solvent and thus improves its electrochemical properties. Moreover, micro-contact printing technology was used to pattern nitroxide polymer brushes on an ITO surface for the potential application in microbatteries. The morphology of electrodes was observed by atomic force microscopy.The electrochemical properties of the cathode were also studies.

Surface plasmon microscopes are mostly built around the prism based Kretschmann configuration. In these systems, an image of a sample can be obtained in terms of an intensity map, where the intensity of the image is dependent on the coupling of the light into the surface plasmons. Unfortunately the lateral resolution of these systems relies on the ability of plasmons to propagate along the metallised layer and is usually limited to a few microns unless special measures are taken. The widefield surface plasmon microscope (WSPR), used here enables surface plasmon imaging at significantly higher lateral resolutions than prism based systems. In this study we demonstrate the functionality of the WSPR by imaging a sequence of binding events between micro-patterned extracellular matrix proteins and their specific antibodies. Using the WSPR system a change in contrast was observed with each binding event. Images produced via the WSPR system were analyzed and compared qualitatively and quantitatively. Consequently, we confirm that the WSPR microscope described here can be used to study sequential monomolecular layer binding events on a micron scale. These results have significant implications in the development of new micron scale bioassays.

Yes / Cell behavior in terms of adhesion, orientation and guidance, on extracellular matrix (ECM) molecules including collagen, fibronectin and laminin can be examined using micro contact printing (MCP). These cell adhesion proteins can direct cellular adhesion, migration, differentiation and network formation in-vitro. This study investigates the effect of microcontact printed ECM protein, namely fibronectin, on alignment and morphology of HeLa cells cultured in-vitro. Fibronectin was stamped on plain glass cover slips to create patterns of 25μm, 50μm and 100μm width. However, HeLa cells seeded on 50μm induced the best alignment on fibronectin pattern (7.66° ±1.55SD). As a consequence of this, 50μm wide fibronectin pattern was used to see how fibronectin induced cell guidance of HeLa cells was influenced by 100μs and single pulse electric fields (PEF) of 1kV/cm. The results indicates that cells aligned more under pulse electric field exposure (2.33° ±1.52SD) on fibronectin pattern substrate. Thus, PEF usage on biological cells would appear to enhance cell surface attachment and cell guidance. Understanding this further may have applications in enhancing tissue graft generation and potentially wound repair. / Ministry of Higher Education Malaysia and UTHM Tier 1 Research Grant (U865)

Scaffold based tissue reconstruction inherently limits regenerative capacity due to inflammatory response and limited cell migration. In contrast, scaffold-free methods promise formation of functional tissues with both reduced adverse host reactions and enhanced integration. Cell-sheet engineering is a well-known bottom-up tissue engineering approach that allows the release of intact cell sheet from a temperature responsive polymer such as poly-N-isopropylacrylamide (pNIPAAm). pNIPAAm is an ideal template for culturing cell sheets because it undergoes a sharp volume-phase transition owing to the hydrophilic and hydrophobic interaction around its lower critical solution temperature (LCST) of 32°C, a temperature close to physiological temperature. Compared to enzymatic digestion via trypsinization, pNIPAAm provides a non-destructive approach for tissue harvest which retains its basal surface extracellular matrix and preserves cell-to-cell junctions thereby creating an intact monolayer of cell sheet suitable for tissue transplantation. The overall thrust of this dissertation is to gain a comprehensive understanding of how tissue precursors are formed, harvested and printed from interactions with shape-changing pNIPAAm hydrogel. A simple geometrical microbeam pattern of pNIPAAm structures covalently bound on glass substrates for culturing mouse embryonic fibroblast and skeletal myoblast cell lines is presented. In order to characterize the cell-surface interactions, three main investigations were conducted: 1) the mechanism of cell detachment; 2) the feasibility of micro-contact printing tissue precursors onto target surfaces; and 3) the assembly of these tissues into three-dimensional (3D) constructs. Detachment of cells from the shape-changing hydrogel was found to correlate with the lateral swelling of the microbeams, which is induced by thermal activation, hydration and shape distortion of the patterns. The mechanism of cell detachment was primarily driven by strain, which occurred almost instantaneously above a critical strain of 25%. This shape-changing pNIPAAm construct allows water penetration from the periphery and beneath the attached cells, providing rapid hydration and detachment within seconds. Cell cultured microbeams were used as stamps for micro-contact printing of tissue precursors and their viability, metabolic activity, local and global organization were evaluated after printing. The formation and printing of intact tissues from the shape-changing hydrogel suggests that the geometric patterning of pNIPAAm directs spatial organization through physical guidance cues while preserving cell functioning. Tissue precursors were sequentially assembled into parallel and perpendicular configurations to demonstrate the feasibility of constructing dense tissues with different organizations such as interconnected cell lines that could induce vascularization to solve perfusion issues in regenerative therapies. The novel approach presented in this dissertation establishes an efficient method for harvesting and printing of tissue precursors that may be applicable for the modular, bottom up construction of complex tissues for organ models and regenerative therapies.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

L'intégration de nano-objets dans des systèmes fonctionnels à l'échelle nanométrique est un sérieux challenge à relever pour les applications qui exploitent leurs propriétés uniques. Ces objets peuvent être de natures diverses et variées, des nano-particules, des protéines, des molécules. De nombreuses problématiques visent à assembler sous forme 2D ou 3D ces nano-objets en suspension dans un liquide sur des surfaces solides. Leur intégration depuis cette phase liquide sur une surface solide, demeure une opération sensible. Une attention toute particulière est alors mise sur l'assemblage de biomolécules ou de nano-particules pour des applications tournées vers l'analyse biologique et le diagnostic médical, mais aussi vers la fabrication de systèmes micro-nano systèmes électromécaniques spécialisés. Le travail présenté dans cette thèse s'inscrit dans cette problématique, il consiste à étudier, comprendre et modéliser les mécanismes physiques mis en jeu dans la technique d'assemblage dirigé par capillarité (mouillabilité, piégeage de la ligne triple sur des motifs artificiels, flux convectifs au sein de la solution). Pour cela nous avons conçu et assemblé un système expérimental d'assemblage capillaire. Un volet technologique a également été développé afin de créer des motifs de piégeage par des méthodes de nanolithographie. Le dernier volet du travail de recherche que nous avons effectué est de nature plus applicative, nous montrons comment un tel procédé peut être utilisé afin d'assembler des nano-objets d'intérêt, autres que des nanosphères parfaites. Nous avons en particulier étudié l'assemblage de brins d'ADN permettant leur peignage organisé sur une surface ainsi que l'assemblage de nanotubes de carbone.

Durant les dernières décennies, de plus en plus de types de cellules se sont révélées capables de sonder leur environnement mécanique par l'application de forces. Ce phénomène appelé «Mecanosensing» est lié à l'adhésion et la mécanique cellulaire, et est souvent étudié grâce à l'interaction des cellules avec des substrats artificiels. Dans des études distinctes, des surfaces chimiquement structurées avec une répartition des ligands spécifiques ont montré une forte influence sur l’adhésion et la mécanique cellulaire. Cependant, la relation entre les deux phénomènes n'a pas été beaucoup explorée, en partie parce que la fonctionnalisation de substrats mous s’est révélée être un défi technique.Pour résoudre ce problème, nous avons développé une technique simple et rentable nommée «reverse contact printing», afin de fabriquer des plots de protéines sub-microniques sur un élastomère d'élasticité contrôlée, le polydiméthylsiloxane (PDMS). Mon travail de thèse a focalisé sur la standardisation et la compréhension du procédé de transfert. A l’aide de mesures de forces réalisées par AFM nous avons mesuré l’élasticité du PDMS, ainsi que les forces de cohésion et d'adhésion effectives impliquées dans le processus. Nous avons également étudié l'adhésion cellulaire avec des lymphocytes-T sur des surfaces de PDMS d'élasticité variable. Nous avons montré que contrairement à la plupart des autres types de cellules, les cellules-T s'étalent davantage sur substrat mou que sur dur. Finalement nous avons réalisé des expériences pilotes d'adhésion cellulaire sur PDMS structuré. / In the past decade, more and more types of cells have been shown to be capable of probing the mechanics of their environment by application of forces. The stiffness of the environment strongly influences a host of cellular parameters including cell adhesion and mechanics. In separate studies, the spatial distribution of ligands, modulated by chemical patterning of a target surface, has been shown to strongly influence cell adhesion and mechanics. However, the cross-talk between the two phenomena has not been much explored, partly because patterned functionalization of soft substrates is an engineering challenge. To address this issue, we have developed a simple and technique named "reverse contact printing" for fabrication of nanometric protein patches on PDMS (polydimethylsiloxane) elastomer. My PhD work consisted of deciphering the molecular mechanisms that underlie this technique. We realized that the rate of transfer crucially depended on the molecular groups on the protein and on the nature of the PDMS surface. We used atomic force microscopy (AFM) force measurements to measure PDMS elasticity as well as protein-substrate interactions to understand the molecular mechanism governing the transfer. We have identified that a successful reverse transfer is facilitated by the grafting of appropriate chemical groups on the protein, and depends on the PDMS surface treatment and elasticity. We also studied adhesion and mechanics of T lymphocytes on PDMS. We found that surprisingly T lymphocytes spread more on softer than on harder PDMS. In on-going pilot experiments, cells on patterned soft PDMS seem to exhibit different behavior as compared to cells on patterned glass.

Grâce à leurs propriétés physiques/chimiques uniques, les nanoparticules colloïdales sont au cœur de nombreuses applications innovantes. Afin de faciliter leur caractérisation ou de les intégrer dans des dispositifs fonctionnels, il est nécessaire de les assembler de manière dirigée sur des surfaces solides. Dans ce contexte, l’objectif de cette thèse est de mieux comprendre et d’optimiser la technique de nanoxérographie, méthode d’assemblage dirigé où des nanoparticules sont piégées sur des motifs de charges électrostatiques. Après un premier travail consistant à améliorer le procédé de nanoxérographie, trois problématiques spécifiques ont été adressées : (i) l’assemblage de particules micrométriques. Le couplage de simulations numériques et de manipulations expérimentales a permis d’identifier les paramètres clés de l’assemblage de telles particules colloïdales et d’élargir (facteur 100) la gamme de tailles de particules assemblables par nanoxérographie. (ii) l’analyse de l’assemblage multicouche. Par le biais de nanoparticules modèles luminescentes et par la mise en place d’un nouveau protocole d’assemblage, les critères clés génériques pour l’assemblage 3D de colloïdes par nanoxérographie ont été dégagés. (ii) l’assemblage dirigé de nanogels sensibles à un stimulus environnemental extérieur. L’utilisation d’un protocole d’assemblage optimisé a permis d’élaborer des assemblages de nanogels interactifs avec leur environnement et du faire du tri sélectif de ces nanoparticules sur une même surface. / Owing to their unique physico-chemical properties, colloidal nanoparticles are building blocks for the creation of plentiful innovative devices. In order to make easier their characterization and to incorporate them into functional nano-devices, it is necessary to perfectly control their directed assemblies onto solid surfaces. In this context, this thesis’ purpose is to simultaneously better understand and optimize the nanoxerography method, which allows electrostatic and selective directing assemblies of nanoparticles onto charged patterns. After an optimization of the nanoxerography process, three specific problematics have been addressed: (1) micron-sized particles assembly. The combined use of numerical simulations and experiments enabled to unveil the key parameters involved in micron-sized particles assembly and to expend the particle size range foreseeable for an assembly by nanoxerography (factor 100). (2) the 3D assembly analysis. The influence of diverse parameters on the 3D assembly of luminescent model nanoparticles was quantified by using a new assembly protocol. The results gave the generic key criterions for the 3D assembly of colloids by nanoxerography. (3) directed assembly of nanogels sensitive to an external environmental stimulus. The use of an optimized protocol allowed elaborating nanogels assemblies interactive with their environment and to sort these nanoparticles onto the same surface.