Polymer waveguides present a potentially low cost alternative to electronics in communication systems. Polymers offer relatively straightforward and economical fabrication when compared to conventional materials. In this study, a fabrication process for Bragg gratings in polymer waveguides was developed. Waveguides were designed using finite-element analysis, patterned via e-beam lithography, and a detailed fabrication method was developed. Surface-Plasmon Resonance (SPR) is a widely accepted method for biological and chemical sensing. Measurement of bulk refractive index changes and specific surface binding is a crucial part in any biosensing. Design and fabrication of a novel self-referencing SPR sensor is described and its functionality is tested.

Surface plasmon waves are TM polarized charge density waves that propagate at the interface of two media with real dielectric constants of opposite sign (i.e. liquid dielectric and certain metals). Surface plasmon resonance (SPR) sensors use these waves to detect refractive index changes adjacent to the metal layer. Refractive index changes arise from the binding of an analyte (e.g. a target molecule, protein, or bacterium) to the functionalized metal layer or from interfering effects such as changes in solution index. Standard, single channel SPR sensors cannot differentiate these two effects as their design allows only one mode to be coupled. This novel self-referencing technique employs two surface plasmon modes to simultaneously measure surface binding and solution refractive index. Dual surface plasmon modes are achieved by matching the refractive indices on either side of the metal film. The two modes generated - symmetric, long-range surface plasmon (LRSP) and anti-symmetric, short-range surface plasmon (SRSP) - have different field profiles and hence assist in differentiating solution refractive index changes from surface layer formation. Amorphous Teflon, with a refractive index close to water, is chosen as the buffer layer and gold is chosen as the metal layer. Magnesium fluoride, with a higher index than Teflon, is used as the buffer layer when using ethanol as the base solution. The sensor operation was optimized through simulations to yield higher sensitivity, lower reflectivity and resonances within the spectrometers range. Optimization results showed good performance over a wide range for Teflon, MgF2 and gold thicknesses which helped in the fabrication of the sensor. Demonstration of self-referencing operation was done through two different sets of experiments: (1) formation of an alkanethiol self-assembled monolayer on gold in the presence of ethanol and methanol solutions having different refractive indices and (2) streptavidin-biotin binding with solutions of different NaCl concentration and thus different refractive indices. In both these experiments, the resonance wavelengths were accurately predicted, reflectivity varied by 10-15% and sensitivity by 25% from that of the simulated values.

Surface plasmons are bound TM polarized electromagnetic waves that propagate along the interface of two materials with real dielectric constants of opposite signs. Surface plasmon resonance (SPR) sensors make use of the surface plasmon waves to detect refractive index changes occurring near this interface. For sensing purposes, this interface typically consists of a metal layer, usually gold or silver, and a liquid dielectric. SPR sensors usually measure the shift in resonance wavelength or resonance angle due to index changes adjacent to the metal layer. However this restricts the limit of detection (LOD), as the regions of low slope (intensity vs. wavelength or angle) in the SPR curve contain little information about the resonance. This work presents the technique of tunable laser interrogation of SPR sensors. A semiconductor laser with a typical lasing wavelength of 650nm was used. A 45nm gold layer sputtered on a BK7 glass substrate served as the sensor. The laser wavelength is tuned to always operate in the region of highest slope by using a custom-designed LabVIEW program. It is shown that the sensitivity is maximized and LOD is minimized by operating around the region of high slope on the SPR curve.

Du fait de leur haute stabilité et bas coût de production, les aptamères suscitent un intérêt croissant, depuis près de 20 ans, dans le design de biocapteurs en tant qu'élément de reconnaissance idéal. Le but de ce travail de thèse est de démontrer l'intérêt et la pertinence d'un outil tel qu'une biopuce à aptamères, associant les avantages des sondes aptamères à ceux d'une détection par SPRi (Surface Plasmon Resonance imaging), permettant une détection sans marquage et en temps réel d'interactions moléculaires. Dans ce but, deux aptamères anti-thrombine (APT1 = 5′- GGT-TGG-TGT-GGT-TGG -3′ et APT2 = 5′-AGT-CCG-TGG-TAG-GGG-AGG-TTG-GGG-TGA-CT-3′) ont été choisis comme objets d'étude modèles. Ce choix a permis d'orienter différents axes de recherche : utilisés indépendamment comme sondes lors de l'élaboration de notre biopuce, ils ont tout d'abord permis de réaliser une détection cinétique optimisée de la thrombine, avec des performances remarquables pour une détection de ce type, ainsi que le calcul de constantes de dissociation en solution et à la surface des biopuces. Mais au-delà d'un simple biocapteur, la biopuce a également pu être utilisée comme véritable plateforme d'étude de la thrombine et de ses interactions, au sein de structures plus complexes telles que la structure " sandwich " entre les deux aptamères, ou d'autres interactions impliquant la thrombine en tant qu'acteur de la cascade de coagulation (inhibition de la thrombine par l'antithrombine III et le cofacteur II de l'héparine, transformation de la prothrombine au sein du complexe prothrombinase).

Protein-protein and protein-molecule interactions are complicated phenomena due to the tendency of proteins to change shape and function in response to their environment. Protein aggregation whether onto surfaces or in solution, can pose numerous problems in industry. Surface plasmon resonance (SPR) devices and quartz crystal microbalances (QCM) are two real-time, label free methods that can be used to detect the interactions between molecules on surfaces. These devices often employ self-assembled monolayers (SAMs) to produce specific surfaces for studying protein-protein interactions. The objective of this work was to develop methodologies utilizing SPR to better understand protein-protein and protein-molecule interactions with possible applications in the food and separation industrial sectors. A very well characterized whey protein, β-lactoglobulin (BLG), is used in numerous applications in the food industry. BLG can undergo different types of self-aggregation due changes in external environment factors such as buffer strength, pH or temperature. In this work, a hydrophilic SAM was developed and used to study the interaction and non-specific adsorption of BLG and palmitic acid (PA), a molecule which is known to bind to BLG. It was found that PA tended to reduce BLG conformational changes once on the surface, resulting in a decrease in its surface adhesion. Fluorescent excitation emission matrices (EEM’s) using a novel fluorescence probe technique were utilized to detect protein on the surface as well as conformational changes on the surface of the sensor, although the extent these changes could not be quantified. Another whey protein, α-lactoglobulin (AL), was utilized as a surrogate protein to study the adsorption of colloidal/particulate and protein matter (CPP) extracted from filtration studies of river water. A large fraction of natural organic matter (NOM), the major foulant in membrane based water filtration, is CPP and protein. Understanding the interactions between these components is essential in abating NOM membrane fouling. Several SPR methods were investigated in order to verify the interactions. A mixture of AL and CPP particles in solution prevented the non-specific adsorption of AL to the SAM surface. This change in association was then detected through SPR. Fluorescent EEM’s of the sensor surface verified that CPP and AL bound to the surface. This finding has fundamental significance in the interpretation of NOM-based membrane fouling. To better understand the mechanisms behind non-specific adsorption, a mechanistic mathematical model was developed to describe the adsorption of BLGs onto the hydrophilic SAM. The resulting model performed well in terms of predicting adsorption based on SPR data. The model incorporated the monomer-dimer equilibrium of BLG in solution, highlighting the impact of protein aggregation on non-specific adsorption mechanisms. For future studies, improvement in fluorescent FOP surface scan methodology would help identify different protein/molecules and conformations on the surface.

Surface immobilization of probe molecules in surface based assays is a key area of research in the continued development of immunoassay microarrays. Interest continues to grow in microarray based immunoassays given their potential as a high throughput technique for immunodiagnostics. Therefore, it is important to thoroughly study and understand the implications of interfacial chemistry and immobilization conditions on the performance of the assay. This thesis presents a body of work that examines the impact of probe density, interfacial chemistry, and enhancement factors for arrays read with surface plasmon resonance (SPR) imaging. An array of structurally similar Salmonella disaccharides was immobilized at varying densities and the interface formed was thoroughly investigated to determine the properties of the interface. The arrays were then used with SPR imaging to evaluate the binding of an antibody specific for one disaccharide of the three stereoisomers on the array. A dilute disaccharide surface was found to provide optimal antibody binding. Higher densities result in steric hindrance of antibody binding by not allowing the disaccharide to insert into the antibody binding pocket. The role of interfacial chemistry in antibody attachment was studied to determine optimum conditions. The study examined physical adsorption, covalent attachment, and affinity capture. It was found that covalent attachment provided the most stable attachment and resulted in the lowest levels of antigen detection. Both the physical adsorption and affinity capture provided larger antigen binding capacity and therefore more sensitive antigen detection. The covalent attachment was chosen to evaluate an enhanced assay with the incorporation of gold nanoparticles. These particles provided detection limits that were an order of magnitude improved over those excluding the nanoparticles. A novel surface chemistry for antibody immobilization in SPR imaging studies was evaluated. This involved the electrochemical driven formation of mono- to multilayers of diazonium benzoic acid films. The studies showed the ability to control the thickness of the films formed and also the ability of the antibody chips to capture antigen from solution.

The present research focused on the development of a new methodology to assess the strength of the interaction between vaccine antigens and elicited polyclonal antibodies through SPR biosensors. Quantifying the binding strength of polyclonal antibodies is of first importance to evaluate the quality of the vaccine as well as to increase the scientific knowledge of immune protection mechanisms. To now the development of such tool has been complicated by the non-specific binding caused by high protein abundance in the blood and serum samples but also by the way of interpreting the data resulting from multi-interaction events measured at the same time. At first, we unsuccessfully tried to segregate the individual affinity contribution of each antibody population by measuring the signal as the sum of singular interactions. Differentiation of the singular contribution would have needed the fulfillment of the “additivity” hypothesis, meaning that each antibody bind identically alone or in mixture with other antibody. This hypothesis was not met and mathematical assessment by the sum of singular contribution led to fitting results that did not reflect the biological reality. It was therefore decided to switch the analysis method and to measure the end association binding level reached by the different samples injected at the same specific antibody content. The dissociation behavior was interpreted by the percentage of binding after long and fixed dissociation time. In a first application, we compared the antibodies elicited by two different commercially available vaccines and we showed that the binding interaction was not concentration dependent as, highly different levels were reached when injecting identical antibody concentration. No statistical significant difference was observed between both vaccines. Research firstly focused on the decrease of the non-specific binding and we found that ionic strength was a key parameter, increasing the buffer salt concentration reduced the non-specific binding without diminishing the binding strength. The sample composition was also a key parameter and purifying the IgG allowed to decrease dramatically the undesired binding events. A second application aimed at showing the equivalence between two different antigen constructions for two antibodies population. Even if identical antigen level immobilization is a challenge, the methodology is completely suitable to perform a 2-dimensional comparison (ligand and analyte). A last application was dedicated to the comparison between D and Q-pan Flu vaccines, and results showed that there was no statistical evidence of significant differences between both vaccines. End association level correlated well with haemagglutination inhibition assay at least when serum samples were not diluted at the same antibody content. This last application also showed that throughput may be extended to more than 50 samples per 80 hours / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

Thin metal films have attracted much interest because they provide a way to produce surface plasmon resonance (SPR) in the Kretschmann configuration. This technique is a very sensitive for determining small changes at the interface between a metallic layer and a dielectric medium, and the metals generally used are silver and gold once their surface plasmon resonances are located in the visible range. Thin films of gold, due their stability and diversity applications, have been extensively studied by electrochemistry, surface enhanced Raman spectroscopy (SERS) and techniques of Microscopic such as AFM and STM. The Raman technique has been used to the analysis of organics compounds in determined system. However, in very low concentration levels is inefficient due to weak signal or interference from noise. A developed method to markedly increase the signal of a species presented at many levels is the SERS. One of the major considerations for the formation of a SERS-active surface is surface roughness, and this has been realized by various ways. In the present work, we analyzed the efects of various oxidation-reduction cycles (ORCs) on the surface of the thin films of gold using the techniques of cyclic voltammetry, microscopy, UV-Vis spectroscopy and SPR, which will be used to evaluate the efficiency of electrochemically modified substrates as SERS and SPR active. Initially, the film was cycling in a solution of H2SO4 to remove impurities from the surface. After this procedure, the 50 nm and 100 nm thick gold films, deposited on a glass substrate, were subjected to a series of ORCs in a solution of H2SO4 containing 0,005 M KCl electrolyte. As the number of ORCs is increased, the roughness of the film increased. We used techniques of microscopy, Spectroscopy UV-Vis, Resonance Plasmon Surface and Cyclic Voltammetry to characterize the surface of the film as a function of roughness. A “home − made” SPR system based on the configuration of Kretschmann was utilized for analyzed the changes provoked in surface film before and after the electrochemically modified. The medium size of the gold islands deposited was analyzed for Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM). This same metallic film, after passing for oxidation processes and reduction, was used to obtain a spectrum SER using an organic molecule the 2-thiouracil adsorbed on the surface of the film. The results observed for AFM, STM and cyclic voltammetry shows that surfaces electrochemically modified increase the roughness, and that the changes modified o depth of the signal SPR. These change provoked electrochemistry after various ORC improve significantly the Raman sign of molecules adsorbed on the surfaces of the metallic films. Finally, we conducted an evaluation of the roughness factor obtained through the techniques of AFM, STM and cyclic voltammetry. _______________________________________________________________________________________ RESUMO: Filmes finos metalicos tem despertado muito interesse devido a possibildade de produzir Ressonancia de Plasmons de Superfıcie (SPR) utilizando uma configuracao de Kretschmann. Esta tecnica e muito sensıvel na determinacao de pequenas mudancas na interface entre uma camada metalica e um meio dieletrico, e os metais usados geralmente sao prata e ouro, uma vez que a ressonancia de plasmon da superfıcie desses metais esta localizada na regiao do visıvel. Esses filmes, devido a sua estabilidade e diversidade de aplicacoes, tem sido extensivamente estudados por tecnicas eletroquımicas, espectroscopia Raman intenficada por superfıcie (SERS) e por tecnicas de microscopia tais como o AFM e STM. A Espectroscopia Raman tem sido utilizada para a analise de compostos organicos em determinados sistemas. No entanto, em sistemas que possuem concentracoes muito baixas, o sinal Raman e extremamente fraco e ineficiente, ou sofre interferencias de ruıdos. Um dos metodos desenvolvidos para aumentar significativamente o sinal de uma especie adsorvida sobre uma superfıcie metalica em varios nıveis e o SERS. Uma das consideracoes importantes para a formacao de um substrato SERS ativo e a rugosidade da superfıcie, e a obtencao dessas superfıcies tem sido realizado de diversas maneiras. No presente trabalho, analisamos o efeito de diferentes ciclos de oxidacao-reducao (ORCs) sobre a superfıcie de filmes finos de ouro, utilizando as tecnicas de voltametria cıclica, microscopias, espectroscopia UV-Vis e SPR, que serao utilizadas para avaliar a eficiencia dos substratos modificados eletroquimicamente como SERS e SPR ativos. Inicialmente, o filme e ciclado em uma solucao de H2SO4 para remover as impurezas da superfıcie. Apos este procedimento, os filmes com espessuras de 50 e 100 nm, depositados sobre um substrato de vidro, foram submetidos a uma serie de ORCs em uma solucao de H2SO4.

The dynamic process of how fast a spintronic device can be switched from one state to another is characterized by the Gilbert damping parameter. It has been found that the Gilbert damping along with other intrinsic properties in permalloy, can be tuned by different dopants and doping concentration. Therefore, a study of intrinsic magnetic properties with emphasis on the dependence of the Gilbert damping parameter from first principles calculations is investigated. It is aimed at to give an insight of the microscopic understanding originated from electronic structure and to provide a guideline in the practical spintronic design. The topic of the present thesis is to investigate, by means of first principle calculations, how the variation of the Gilbert damping parameter depends upon the electronic structure of pure and doped permalloy. We show that the Gilbert damping has a monotonic increase with the doping concentration due to an increasing amount of scattering processes. The dopants of the 5d transition metal give rise to a much larger impact than the 4d, as the spin orbit coupling effect is more pronounced in the heavy elements. Our results are in satistying agreement with experiment. / <p>QC 20150629</p>

This essay examines the paranormal in Stephen King’s novel The Shining to investigate if there is a parapsychological motif and how that affects the narrative. This is achieved by analysing the abilities that the Torrance family, Dick Hallorann, and the Overlook exhibit and how these abilities are linked to established terminology within the parapsychological research area. The main focus will be on correlations between The Shining and research that has been carried out within anomalistic psychology and parapsychology. Structuralist literary theory is used to investigate all parts of the narrative. Both a mimetic and a semiotic reading are applied. This is done first by performing a comparative analysis from a Gothic structural perspective. Furthermore, an analysis of the paranormal abilities the characters exhibit and likewise the paranormal phenomena in the narrative is done. Finally, the abilities and phenomena are linked to the terminology used within the paranormal research field. The conclusion is that there is a correlation between the scientific paranormal terminology and Kings description of the characters' abilities, as well as the phenomena in the narrative. / Uppsatsen undersöker det paranormala i Stephen Kings roman Varsel för att utreda om det finns ett parapsykologiskt motiv i berättelsen samt i så fall hur ett parapsykologiskt motiv påverkar berättelsen. Studien analyserar därför förmågorna som familjen Torrance, Dick Hallorann och Overlook uppvisar och hur dessa förmågor kan länkas med den kända terminologin inom det parapsykologiska forskningsområdet. Huvudfokus ligger på att studera korrelationer mellan Varsel och forskningen som utförts inom den anomalistiska psykologin och parapsykologin. Strukturalistisk litteraturteori kommer att användas för att undersöka alla delar av berättelsen genom tillämpning av både mimetisk och semiotisk läsning. Detta genom att först utföra en komparativ analys från ett gotiskt strukturellt perspektiv för att sedan undersöka vilka paranormala förmågor persongalleriet uppvisar och slutligen länka dessa till den terminologi som används inom det paranormala forskningsområdet. Slutsatsen blev att studien fann ett samband mellan den vetenskapliga paranormala begreppsbilden och Kings beskrivning av karaktärernas förmågor samt intrigens fenomen i Varsel.