Herein is presented the collective experimental record of research performed in the Laboratory for Biological Surface Science. These investigations are generally classified under the category of bioanalytical surface science and include the following projects. Chapters III and IV describe the creation of a microfluidic device capable of generating fixed arrays of concentration gradients. Experimental results were matched with computational fluid dynamics simulations to predict analyte distributions in these systems. Chapters V and VI demonstrate the discovery and utility of photobleaching fluorophores for micropatterning applications. Bleached fluorophores were found to rapidly attach to electron rich surfaces and this property was used to pattern enzymes inside microfluidic channels in situ. Finally, Chapter VII exhibits a method by which solid supported lipid bilayers can be dried and preserved by specifically bound proteins. The intrinsic property of lateral lipid mobility was maintained during this process and a mechanism by which the protein protects the bilayer was suggested.

Herein is presented the collective experimental record of research performed in the Laboratory for Biological Surface Science. These investigations are generally classified under the category of bioanalytical surface science and include the following projects. Chapters III and IV describe the creation of a microfluidic device capable of generating fixed arrays of concentration gradients. Experimental results were matched with computational fluid dynamics simulations to predict analyte distributions in these systems. Chapters V and VI demonstrate the discovery and utility of photobleaching fluorophores for micropatterning applications. Bleached fluorophores were found to rapidly attach to electron rich surfaces and this property was used to pattern enzymes inside microfluidic channels in situ. Finally, Chapter VII exhibits a method by which solid supported lipid bilayers can be dried and preserved by specifically bound proteins. The intrinsic property of lateral lipid mobility was maintained during this process and a mechanism by which the protein protects the bilayer was suggested.

The motivation for the current work stems from a unique application, i.e. the photopatterning of optical functionality in a photosensitive material immediately prior to use. In this case, optical devices such as diffraction gratings and optical interconnects are produced in thin films using integrated photonic sources under relatively uncontrolled environmental conditions. The compatibility of the material photoexcitation mechanism with wavelength and fluence levels available from compact solid-state optical sources and the need to understand the impact of local atmospheric composition and temperature on the photosensitive material response are therefore of primary concern. The primary goal of the current study was to investigate photoexcitation mechanisms and photoinduced optical and structural changes in promising candidate material systems for this application: polysilane and polygermane-based molecular hybrid polymers. The work pursued the development of a fundamental understanding of the key photophysical and photostructural responses of thin films composed of both pure, linear-chain polysilanes and of a Ge-Si copolymer. The effects of molecular modifications to the polymers, including polymer backbone catenate structure and side-group identity, on the optical and photosensitive behavior observed in these systems are examined. Through such effort, an understanding of how such structural characteristics influence key photosensitive properties, i.e. the excitation wavelength and the resulting photoinduced optical property changes, was attained. A related objective in the present work was to characterize the thermal stability of these hybrid polymers, specifically in terms of the effect of thermal treatment on as-deposited and photomodified materials. In this case, an evaluation of the similarities and differences in structural modification in response to both thermal and optical fields was pursued. The primary mechanism associated with the photoinduced phenomena observed in both polysilane and polygermane involves backbone chain scissioning and the formation of silane-radicals upon absorption of near-UV (λ ≈ 300 to 400 nm) photons, resonant with the lowest energy, σ - σ* (HOMO-LUMO) transition of the Group IVA backbone. The final photoproducts obtained result from a mixture of different competing processes which occur subsequent to this initial photoscissioning. In aerobic atmospheric environments, the radicals formed capture oxygen and form oxide linkages forming the dominant photoproducts. On the other hand, under anaerobic conditions, photooxidation is suppressed while hydride passivation of the radical dominates the response. The oxidized product, resulting from irradiation under the aerobic environment, exhibited higher refractive index changes than irradiation under anaerobic conditions. Photoexcitation using higher energy photons (typically λ ≈ 230 to 300 nm) are resonant with side-group transitions associated with π-conjugated states of the cyclic moieties. Under these conditions, the excitation accesses both these organic side-groups as well as the Group IVA backbone structure. Such excitation conditions resulted in a larger photoinduced structural modification in the irradiated polymer, as observed both in terms of its electronic structure as well as the resulting refractive index change. Thermally induced structural modification to the backbone and side-group moieties were found to be qualitatively similar those produced under optical irradiation. For example, the primary structural changes were again associated with backbone chain scissioning. Photoinduced structural modifications through resonant optical excitation of the material, however, tended to be more focused on the specific structural moieties accessed.

No description available.

Functional immobilization and lateral organization of proteins into micro- and nanopatterns is an important prerequisite for miniaturizing analytical and biotechnological devices. In this thesis I present novel and versatile approaches for high contrast surface micropatterning of proteins, artificial membranes and live cells based on maleimide photochemistry. The patterning strategy is carried-out on glass substrates exploiting a poly(ethylene glycol) PEG polymer layer as a compatible scaffold. The flexible PEG cushion prevents unspecific proteins attachment and cell adhesion to surfaces. The versatility of this method is demonstrated by means of different orthogonal chemistries using covalent- and affinity- based interactions for protein immobilization. Furthermore, using maleimide based alkyl-thiol chemistry, I utilized the patterning approach for capturing liposomes and proteoliposomes onto surfaces. Formation of fluid patterned polymer-supported membranes demonstrating lateral diffusion of lipids and proteins was confirmed by biophysical assays. A similar approach was used for micropatterning of transmembrane proteins in surface adhered live cells.

Ce travail de thèse a pour objectif l’étude de l’électrochimiluminescence (ECL) et son application pour le développement de nouvelles techniques analytiques. De par son importante sensibilité, l’ECL est une technique performante pour des applications telles que les diagnostics cliniques ou la chimie environnementale (présence d’agents contaminants dans l’eau ou la nourriture). L’immobilisation du luminophore ECL est réalisée généralement sur une phase solide. Cette étape constitue une phase essentielle pour obtenir une méthode d’immobilisation rapide, simple, flexible et efficace de ces luminophores ECL, tout en permettant une utilisation pour des systèmes variés. La première partie de ce travail présente l’optimisation de la déposition électrochimique de films de métallopolymère de ruthénium et son application pour la détection enzymatique. Un film d'épaisseur micrométrique de cet hydrogel redox a été préparé par voltamétrie cyclique. Cet hydrogel immobilisé a permis la détection d’un substrat modèle (le glucose) en utilisant l'enzyme glucose déshydrogénase. La seconde partie se concentre sur le développement d’une nouvelle méthode de photodéposition d’un polymère. Celle-ci permet l’immobilisation de centres actifs sur des régions sélectives. En utilisant les techniques de photolithographie, les figures du masque sont projetées sur la surface des électrodes. Cela permet la réalisation de spots micrométriques dont la taille, forme et épaisseur sont modulables. Les propriétés électrochimiques des films nanométriques obtenus sont comparables à ceux obtenues par électrodéposition. De même, les spectres ECL réalisés avec polymères immobilisés par ces deux stratégies sont identiques. Ces résultats montrent que les états excités induits lors de l’ECL sont identiques avec les deux techniques d’immobilisation. Le développement d'un tel procédé constitue une alternative prometteus pour la réalisation de réseaux de spots ECL différenciés et permettant la détection multipléxée par imagerie ECL. Dans la troisième partie de ce travail, nous avons associé la spectroélectrochimie et l'imagerie ECL pour contribuer à l’étude des mécanismes ECL au niveau d'une bille micrométrique fonctionnalisée par des complexes de ruthénium. En combinant microscopie de fluorescence et imagerie ECL, la distribution des sites électroactifs et des sites ECL a pu être mise en évidence. A partir de cette étude, nous pouvons clarifier les mécanismes conduisant à l'émission ECL au niveau de ces billes fonctionnalisées. / The main goal of this thesis was to study electrogenerated chemiluminescence (ECL) and its application in development of new analytical techniques. Due to its high sensitivity, ECL presents a powerful method for applications in clinical diagnostic and environmental chemistry (presence of contaminants in water or food). The immobilisation of an ECL luminophore is usually performed on a solid phase. This step is an essential point to obtain a technique for fast, simple, flexible and effective immobilisation of ECL luminophores with possibility of applications in various configurations. The first part of this work presents the optimisation of the electrochemical deposition of a ruthenium metallopolymer and its application in enzymatic detection. A redox hydrogel film with micrometric thickness was prepared using cyclic voltammetry. This immobilised hydrogel allows the detection of model substrate (glucose) using enzyme glucose dehydrogenase. The second part of this thesis is focused on the development of a new photodeposition method for the ECL polymer immobilisation. This method allows region-selective immobilisation of active centres. Using photolithographic methods, the figures from the mask are projected on the electrode surface. This allows the formation of micrometric spots which size, shape and thickness is modulated. Electrochemical properties of obtained nanometric films are comparable with those of electrodeposited films. Also, ECL spectra recorded with both immobilisation strategies are identical. It shows that the ECL excited state is the same. The obtained photopatterns were imaged using ECL. The development of such process presents an alternative for realisation of different ECL spot arrays and allows multiplexed detection by ECL imaging. In the third part of this work we have associated spectroelectrochemistry and ECL imaging to study the ECL mechanisms at the level of a single microbead, functionalised with ruthenium complex. Combining fluorescence microscopy and ECL imaging, the distribution of electroactive and ECL sites have been highlighted. From this study we can clarify the mechanism that leads to ECL emission at the level of functionalised beads.

The research described herein is aimed at exploring the thermo-mechanical properties of thiol-ene polymers in bulk form, investigating the ability of thiol-ene polymers to behave desirably as photolithographic media, and providing the first characterization of the mechanical properties of two-photon stereolithography-produced polymer structures. The thiol-ene polymerization reaction itself is well-characterized and described in the literature, but the thermomechanical properties of thiol-ene and thiol-ene/acrylate polymers still require more rigorous study. Understanding the behavior of thiol-ene networks is a crucial step towards their expanded use in bulk form, and particularly in specialized applications such as shape memory devices. Additionally, the thiol-ene polymerization reaction mechanism exhibits unique properties which make these polymers well suited to photolithography, overcoming the typical dichotomy of current materials which either exhibit excellent photolithographic behavior or have controllable properties. Finally, before two-photon stereolithography can create mechanisms and devices which can serve any mechanically functional role, the mechanical properties of the polymers they produce must be quantitatively characterized, which is complicated by the extremely small scale at which these structures are produced. As such, mechanical characterization to date has been strictly qualitative. Fourier transfer infrared spectroscopy revealed functional group conversion information and sol-fraction testing revealed the presence of unconverted monomer and impurities, while dynamic mechanical analysis and tensile testing revealed the thermomechanical responses of the systems. Nanoindentation was employed to characterize the mechanical properties of polymers produced by two-photon stereolithography. Optical and electron microscopy were exploited to provide quantitative and qualitative evaluations of thiol-ene/acrylate performance in small-scale polymerization regimes. The broad objective of the research was to explore thiol-ene polymer behavior both in bulk and at the small scale in an effort to supplement the material library currently used in these fields and to expand the design envelope available to researchers. The significance of the research is the advancement of a more complete and fundamental understanding of thiol-ene polymerization from kinetics to final properties, the quantitative establishment of the mechanical properties of materials created with two-photon stereolithography, and the comprehensive characterization of a supplementary class of photopatternable polymers with greater property tunability than is possible with currently used materials.

This thesis studies the different ways in which the localized plasmon heating effect of gold nanostructures -activated by plasmon excitation via visible and/or NIR irradiation- can be used to obtain different outcomes following the nanofabrication of applicable devices. Both spatial and temporal control were obtained for each one of the systems developed upon the incorporation of plasmonic gold nanostructures. Spatial control was enabled in hybrid mesoporous drug delivery systems fabricated in this thesis through the localized surface plasmon heating effect that allowed the modification of the dynamics of diffusion of the cargo being delivered, thus giving rise to different rates of release that can be controlled by plasmon excitation. At the same time, the plasmon heating effect proved to be capable of controlling the start of the release by dismantling thermo-responsive gates previously incorporated, thus enabling also a wavelength-controlled feature that enhances the versatility of these systems. Spatial control was also conferred to the photo-patterning applications presented in this dissertation by influencing the degree of motility of gold nanorods (AuNRs) embedded in polymer matrices allowing them to self-assemble when the longitudinal plasmon of the incorporated nanostructures was excited; the patterns generated were quite robust and persisted for extended periods of time. Finally, the feature of spatial heating control was also conferred to catalysis. The Friedel-Crafts alkylation of anisole by benzyl chloride using spherical gold nanoparticles (AuNPs) supported on Nb2O5-based catalysts was performed at bulk temperatures below those necessary for the reaction to occur when using bare or modified Nb2O5; this was the result of the combination of bulk and localized plasmon heating produced -both- via plasmon excitation. This also demonstrates the possibility of using plasmon excitation as an alternative heat source in this type of reactions. By combining the plasmonic properties of metallic nanostructures with those granted by mesoporous materials, polymer matrices and Nb2O5-based materials it was possible to obtain light-activated systems endowed also with temporal control and wavelength control while preserving the original properties of each systems' components. Overall, the content of this thesis describes in detail the practical aspects of combining gold nanostructures with different materials and the rationale behind the development of systems with customized and controllable properties.

Le contrôle spatial et temporel de l'auto-assemblage de molécules fluorescentes en nano-objets organisés et en matériaux mous a été réalisé par photochimie.La photodécarbonylation quantitative du progélifiant dkDDOA sous irradiation génère le super gélifiant 2,3-didécyloxyanthracène (DDOA) à température ambiante et simultanément gélifie le DMSO. DkDDOA est réactif sous excitation avec de la lumière bleue en raison de la fonction alpha-dicétone sensible à la lumière qui est ajoutée au noyau aromatique. De plus,l’ajustement de la couleur de l'émission du gel du bleu au vert a été obtenu en ajoutant un dérivé 1,2-dicétone-5,12-diphényltétracène photo réactif qui donne un 5,12-diphényltétracène émissif vert sensibilisé par un transfert d'énergie efficace.Sous un microscope, l'irradiation laser focalisée permet la structuration de nanofibres émissives sur une surface de verre. Bien que la surface de verre soit non traitée, on peut obtenir des micropattern de nanofibres de DDOA hautement alignées. Ces surfaces émettent une lumière bleue polarisée linéairement, comme le prouve la microscopie de polarisation. L'anisotropie élevée et l'orientation des fibres ont été obtenues en contrôlant la densité de nucléation et la direction de balayage du laser focalisé. Des micropattern orientés perpendiculairement peuvent ainsi être juxtaposés sur la même surface. / The spatial and temporal control of the self-assembly of fluorescent molecules into organized nano-objects and into soft materials was achieved by photochemistry. The quantitative photodecarbonylation of the progelator dkDDOA under irradiation generates the supergelator 2,3-didecyloxyanthracene (DDOA) at room temperature and simultaneously gelates DMSO. dkDDOA is reactive under excitation withblue light due to the light sensitive alpha-diketone moiety that is added to the aromatic core.Additional colour-tuning from blue to green emission from the gel was achieved by adding a similar photoreactive 1,2-diketone-5,12-diphenyltetracene that yields a green emissive 5,12-diphenyltetracene sensitized through an efficient energy transfer. Under a microscope, focused laser irradiation enables the patterning of blue-emissive nanofibers on to a glass surface. Although the surface is non-treated, micropatterns of highly aligned DDOA nanofibers can be obtained. These surfaces emit linearly polarized blue light,as proven with polarization microscopy. The high anisotropy and the orientation of the fibers was achieved by controlling the nucleation density and the direction of scanning of the focused laser. Perpendicularly oriented micropatterns can thereby be juxtaposed on the same surface.

No description available.