In linear accelerator driven 4th generation Free Electron Lasers (FELs), the final beam quality is set by the linac and ultimately by its photoinjector and photocathode. Therefore, to deliver cutting-edge beam characteristics, there are stringent requirements for the photocathode used in the photoinjector. Understanding how surface properties of materials influence photocathode properties such as quantum efficiency (QE) and intrinsic emittance is critical for such sources. Metal photocathode research at Daresbury Laboratory (DL) is driven by our on-site accelerators VELA (Versatile Electron Linear Accelerator) and CLARA (Compact Linear Accelerator for Research and Applications), a free electron laser test facility. Metals offer the advantage of a fast response time which enable the generation of short electron pulses. Additionally, they are robust to conditions within the gun cavity. The main challenge with metal photocathodes is to maximise their (relatively) low electron yield. In this PhD thesis, the goal has been to carry out an experimental investigation on alternative metals to copper, correlating surface properties with photoemissive properties. A range of surface analysis techniques have been employed: surface composition was investigated using X-ray Photoelectron Spectroscopy and Medium Energy Ion Scattering, Kelvin Probe apparatus and Ultra-violet Photoelectron Spectroscopy were used to measure work function, and Atomic Force Microscopy and Interferometric microscope provided images characterising surface morphology. The photocathode properties studied include: QE measured using a 265 nm UV LED source that was later upgraded to a 266 nm UV LASER, and Mean Transverse Energy measured using the Transverse Energy Spread Spectrometer. As a result of this work, Mg, Nb, Pb, Ti and Zr have all been identified as photocathode candidate materials, each exhibiting a QE greater than Cu. Additionally, surface preparation procedures for optimising QE from a selection of metals has been explored; the findings of these experiments would suggest that ex-situ Ar plasma treatment followed by in-situ heat treatment is well suited to remove surface contaminants without altering the surface morphology of the cathode. As part of this work, metallic thin films produced by magnetron sputtering have been produced; ultimately the chosen cathode metal will be deposited onto a cathode plug which will be inserted into the electron gun that will drive CLARA. Thus the preparation of metal thin films has been investigated and the effect of different substrate materials on the film properties has been explored. Preliminary experiments studying the effects of surface roughness on photoelectron energy distribution have been conducted; the findings have not been conclusive, thus further systematic studies are required.

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Bilateral breast augmentation is one of the most common cosmetic surgical procedures carried out on women in the western world. Breast augmentation involves increasing the volume of a woman‘s breasts through surgery by placing a silicone implant in the subglandular or subpectoral cavity. Although a capsule forms inevitably around breast implants as a natural part of healing, it can cause significant morbidity if the capsule becomes firm and contracted, a condition known as breast capsular contracture (BCC). The aetiology of BCC remains unknown however it is characterised by dense fibrocollagenous connective tissue with a local inflammatory response. Host response is influenced by several factors including implant surface texture, chemistry and interactions between cells and the extracellular matrix. Texturing holds the implant in place, thus preventing micromotion at the host prosthesis interface. While in smooth surfaces, the implant moves inside the breast, making the fibroblasts repeatedly produce collagen in response to this host-prosthesis shearing motion. In this thesis, the effect of surface characteristics and specific coatings on the cell-surface interaction has been examined on smooth compared to textured surfaces using commercially available breast implants. The properties of breast implants shells have been characterised using confocal laser microscopy, contact angle measurements, confocal Raman spectroscopy and tensile testing. Confocal laser microscopy was used to evaluate the topographical features and surface roughness of the implant surfaces. Contact angle measurements were carried out to determine the hydrophobicity of the implant surfaces. Chemical characterisation was carried out recording Raman images and spectra of the implants using confocal Raman spectrometer. The mechanical properties of the breast implant shells were measured via tensile testing. Adhesive interactions of breast-derived fibroblasts with breast implant surfaces were examined in-vitro. For this purpose, the effect of four molecule coatings (aggrecan, collagen I, fibronectin, and hyaluronic acid) was evaluated on fibroblast attachment, proliferation, fibroblast morphology, spreading, cytotoxicity and gene expression. Results from in-vitro assays demonstrated cell susceptibility to topography and protein coatings and further showed cytoskeletal re-organisation and modification with specific cell adhesion patterns. Combination of diverse topographies and specific coatings induced differential regulation of the expression of adhesion related genes, such as focal adhesion kinase, paxillin, vinculin, and α-actinin on breast fibroblasts. In conclusion, this thesis has demonstrated the extent and strength of cell adhesion and subsequent cell proliferation and differentiation. This is based on the physical interactions between cells and the extracellular environment in the form of topography and on the chemical interactions mediated by specific coatings. Precise characterisation of the silicone breast implant surfaces was achieved. This may play an important role in the development of improved breast implant surfaces with improved qualities leading the development of surfaces that may be less prone to capsular contracture.

Ce travail de thèse s’inscrit dans la partie caractérisation d’un projet collaboratif ayant pour objectif d’élaborer des textiles antimicrobiens pour différents domaines d’application, en particulier les domaines de la santé et de l’agroalimentaire. La démarche analytique a consisté à combiner différentes techniques d’analyse de surface (techniques microscopiques (SEM, AFM, TEM) et spectroscopiques (XPS, ToF-SIMS, SIMS, EELS)) avec des analyses microbiologiques pour aider à la compréhension des mécanismes de protection antimicrobienne des textiles traités. Les agents antimicrobiens, l’argent et le Poly HexaMéthylène Biguanide (PHMB), ont été déposés respectivement par plasma (PVD / PECVD) et par foulardage. Les contraintes liées aux domaines d’application des textiles étudiés (implants herniaires et vêtements professionnels) ont été prises en compte (respectivement, quantité minimale de l’agent antimicrobien et résistance au lavage industriel). Malgré certaines contaminations inhérentes à des procédés industriels, les analyses de surface se sont révélées être un ensemble d’outils essentiel au développement des procédés (qualité du dépôt, influence des conditions de dépôt, influence du lavage). Selon les domaines d’application, l’analyse à très haute sensibilité en extrême surface et l’étude de la distribution en profondeur de l’agent antimicrobien ont été des étapes clés pour la compréhension des propriétés antimicrobiennes observées pour les dépôts, démontrant la pertinence de l’approche multi-analytique choisie dans ce travail de thèse / This thesis work concerns the characterization effort within a cooperation project aiming at developing antimicrobial textiles for various application fields, particularly health applications and food-processing industry. The analytical approach combined different surface analysis techniques (microscopy techniques (SEM, AFM, TEM) and spectroscopy techniques (XPS, ToF-SIMS, SIMS, EELS)) to microbiological tests in order to understand the antimicrobial activity of deposits at the surface of textiles. Silver and Poly Hexamethylene Biguanide (PHMB) antimicrobial agents were deposited by plasma (PVD / PECVD) and padding, respectively. Specific constraints related to the application fields (hernia implants and clothing) were considered (minimum concentration in antimicrobial agent and resistance to industrial washing, respectively). Despite some ubiquitous contamination related to industrial processes, surface analysis techniques proved to be an essential help to develop these processes (deposit quality, influence of deposition conditions, influence of washing). Depending on the application fields, high sensitivity surface analysis at the extreme surface and in-depth distribution of the antimicrobial agent were essential to understand the antimicrobial properties of the deposits, which confirms the relevance of the multi-analytical approach used in this thesis work

Les microsphères polymériques, biodégradables et biocompatibles sont prometteuses comme échafaudages pour fournir des cellules aux tissus sans dommage et améliorer la réponse des cellules souches. Il a été montré que les microparticules à base de PLGA à base de protéines ECM préparées par une technique d'extraction par solvant en émulsion améliorent l'adhésion et la prolifération des cellules souches. Bien qu'un certain effet biologique du revêtement protéique sur les microparticules de polymère soit établi, il n'est pas bien compris car des informations détaillées sur l'interaction entre les propriétés de surface des particules chimiques et physiques, l'adsorption protéique et la réponse cellulaire restent floues. Le but de cette étude est d'établir une relation entre les propriétés de surface des particules qui proviennent des variables utilisées lors des formulations, l'adsorption des protéines et la réponse des cellules souches pour permettre une conception plus rationnelle des microparticules. Deux types de polymères différents (PLGA et PLGA-P188-PLGA) et deux stabilisants d'émulsion différents; un polymérique PVA et une huile polaire Propylène glycol ont été utilisés pour préparer quatre types de particules dans un procédé en émulsion. Les particules ont été caractérisées en termes de taille, charge, topographie et morphologie et chimie de surface Identification des effets des variables dans la chimie et l'émulsifiant des polymères Des surfaces de polymère plat recouvertes de spins sont générées pour comprendre les interactions entre les polymères et les molécules d'adhésion de la fibronectine et de la poly-D-Lysine pour la fonctionnalisation des microparticule. / Polymeric, biodegradable and biocompatible microspheres are promising as colloidal scaffolds to deliver cells to tissues without damage and to enhance stem cell survival. It has been shown that PLGA (poly(lactic-co-glycolic acid)) based microparticles prepared by an emulsion solvent extraction technique and functionalised with ECM proteins improves stemcell adhesion and proliferation. While it is established that the presence of proteins in these systems has abiological effect, the interplay between microparticle properties and cells is poorly understood because there lationship between chemical and physical particle surface properties, protein adsorption and cell response remain unclear. Protein adsorption on a polymer particle surface is a complex phenomenon that is affected by different interfacial mechanisms/forces (e.g. DLVO and non-DLVO forces) and inherents tructural properties of macromolecules (e.g. polymers, surfactants, peptides and proteins) present on surface, establishing the parameters that involves inprotein/peptide adsorption on microparticles insights the logical design of the particles as a biomaterial useby contributing the understanding of another related complex phenomenon of the colloidal biomaterial-cell interface interaction in tissue engineering where limited study available to fully understand the concept.The purpose of this study is to investigate the impact of different formulation approaches on the physicochemical properties of the microparticles and identify connections between the particle properties, protein adsorption and ensuing cell response on these materials. To examine these, two different polymertypes (PLGA and PLGA-P188-PLGA) and two different emulsion stabilizers; a polymeric surfactant (PVA(Polyvinyl alcohol) and a polar oil propylene glycol were used to prepare four different types of particles in an emulsion process (O/W). Particles were characterized in terms of size, charge, topography, morphology and surface chemistry to identify the effect of the variables of polymer chemistry and use of surfactant on particle properties in first part of the study. Spin coated flatpolymer surfaces were generated to understand the interactions between the polymers and the proteins (fibronectin /poly-d-Lysine).

Le polymorphisme revêt un grand intérêt dans le domaine pharmaceutique puisqu’il concerne plus de 80% des principes actifs (PA). Les différences de propriétés physicochimiques entre deux polymorphes peuvent influer sur la mise en forme galénique de la molécule active, sa biodisponibilité, sa stabilité lors du stockage voire même sur son activité. D'un point de vue industriel, l'hétérogénéité de surface d'un solide pharmaceutique semble jouer un rôle fondamental, lors de sa mise en forme mais aussi lors de son stockage. Néanmoins, les interactions de surface avec l’environnement de ce type de solides sont des phénomènes de faible amplitude et donc très difficiles à quantifier. Les techniques de mouillabilité, les plus utilisées, relient le travail d’adhésion à l’énergie de surface par la mesure de l’angle de contact entre le solide et un liquide. La valeur de l’énergie de surface obtenue, n’a qu’un caractère statistique qui caractérise un comportement macroscopique global du solide d’étude. Cette notion perd toute signification à l’échelle microscopique et donc ne répond pas aux besoins actuels de l’industrie pharmaceutique. L’objectif de cette étude est donc de quantifier l’anisotrope énergétique de surface des solides d’intérêt pharmaceutique. La Chromatographie Gazeuse Inverse (CGI) apparaît alors comme une méthode de choix pour caractériser les propriétés de surface de solides divisés. L’étude de l’énergie de surface par CGI à dilution infinie, au travers d’une étude rigoureuse du domaine de Henry, nous a permis de distinguer, en surface, les formes polymorphes α, β et δ du D-mannitol. De plus, elle nous a permis de faire un lien entre la composante dispersive de l’énergie de surface et des procédés de génération et de mise en forme, tels que l’atomisation et le cryobroyage. Les augmentations d’énergie de surface à la suite de ces procédés ont été attribués aux changements intrinsèques de la particule, telles que sa taille et sa morphologie. / The polymorphism phenomenon is of great interest in the pharmaceutical field since it concerns more than 80% of the active pharmaceutical ingredients (API). Differences in physicochemical properties between polymorphs are known to influence the formatting dosage of the active molecule (compression during tableting), bioavailability, toxicity and stability under storage conditions. From an industrial point of view, the surface heterogeneity of pharmaceutical solids seems to play a fundamental role in formatting but also during storage. However, organic solid’s surface interactions are small amplitude phenomenon and therefore very difficult to quantify. Wettability techniques, the most commonly used, relate the work of adhesion to the surface energy by measuring the contact angle between the solid and a liquid. The value of the surface energy obtained has a statistical nature that characterizes a global macroscopic behavior of the solid. This concept becomes meaningless at microscopic level and therefore does not respond to the existing and growing needs of the pharmaceutical industry. The objective of this study is to quantify the anisotropic surface energy of pharmaceutical solids. The inverse gas chromatography (IGC) will appear as the technique of choice for characterizing divided solid surface properties. The study of the surface energy using IGC at infinite dilution, through a rigorous study of Henry’s domain, allowed us to distinguish the polymorphic forms α, β and δ of D-mannitol. In addition, we were able to make a connection between the dispersive component of the solid’s surface energy and the generation and forming processes, such as spray drying (SD) and cryo-milling (CM). Surface energy increments after SD and CM were attributed to changes of the intrinsic characteristics of the particles such as size and morphology.

Ces travaux de thèse portent sur l’étude et l’optimisation des propriétés interfaciales verre/PA 6-6 pour la conception de matériaux composites de structure. Une méthode visant à nettoyer et réactiver la surface du verre a dans un premier temps été développée. Elle permet de travailler avec des substrats de type fibres ou substrats modèles (plaques de verre) et d’obtenir des surfaces « contrôlées » avant l’application de nouveaux revêtements. La maîtrise de l’interface entre renfort et matrice nécessite l’optimisation de l’ensimage, dont les principaux constituants sont des agents filmogènes et des agents de couplage. Au cours de ce travail, nous avons donc étudié les propriétés thermiques, mécaniques et de surface des nouveaux revêtements appliqués sur les substrats de verre. Différents agents filmogènes, sélectionnés pour être compatibles avec les conditions de mise en oeuvre du PA 6-6, ainsi que deux agents de couplages usuels ont été étudiés. Par le choix d’une large gamme de familles d’agents filmogènes, nous avons montré que l’utilisation d’un agent filmogène de composition chimique proche de celle de la matrice permet d’atteindre de meilleures propriétés interfaciales. L’augmentation de la rugosité de surface du revêtement contribue également à cette amélioration. Le greffage des agents de couplage sur le verre s’est révélé bien plus efficace avec un traitement thermique à 150°C qu’à 110°C et un effet de synergie a pu être observé lors de leur association avec un agent filmogène. L’utilisation d’agents filmogènes à haute résistance thermique a permis d’obtenir des propriétés interfaciales très intéressantes, renforcées pour certains systèmes par l’ajout de nanoparticules. Enfin, afin d’accéder à une estimation de la ténacité de l’interface, un test de DCB en mode I a été adapté à notre problématique. Les résultats obtenus ont été complémentaires à ceux obtenus par les tests du plot et de la microgoutte / This work is devoted to the study and optimisation of glass/PA 6-6 interfacial properties for the conception of structural composite materials. A method to clean and reactivate glass surface was first developed. It allowed us to work with glass fibres and model substrates (glass plates), aiming to get controlled surfaces before the application of new coatings. Controlling the interface between the reinforcement and the matrix requires the optimisation of the sizing, which is mainly composed of film formers and coupling agents. This study consisted in the characterisation of thermal, mechanical and surface properties of the new coatings applied to the glass substrates. Different film former bases, selected for their compatibility with the processing conditions of PA 6-6, and two usual coupling agents were studied. This work allowed to identify different parameters that play a role in the improvement of interfacial properties. By working with a wide range of film formers, we could show that the use of a film former with close chemical composition from the matrix allows to reach better interfacial properties. Increasing the surface roughness of coatings also participates in this improvement. The grafting of coupling agents was more efficient after 150°C thermal treatment than 110°C, and a synergistic effect was obtained by their association to a film former. The use of film formers with high thermal resistance provided very interesting interfacial properties, also improved, for some, by the addition of silica nanoparticles. Finally, DCB mode I mechanical test was adapted to our system, allowing to estimate the fracture toughness of the glass/PA 6-6 interface which is a complementary result to the estimation of the adhesion force measured by pull-off and pull-out tests