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Dissertations / Theses on the topic 'Optical Biosensors'
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Nightingale, Joshua Ryan. "Optical biosensors SPARROW biosensor and photonic crystal-based fluorescence enhancement /." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5818.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vi, 120 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 91-100).
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Cullen, David Charles. "Conductimetric & optical biosensors." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293445.
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Zourob, Mohammed M. "Development of optical waveguide biosensors." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743091.
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Urmann, Katharina [Verfasser]. "Aptamer-based optical biosensors / Katharina Urmann." Hannover : Technische Informationsbibliothek (TIB), 2018. http://d-nb.info/1166271978/34.
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Mohd, Salleh Mohd Hazimin. "Polymer waveguide micro-resonators for optical biosensors." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2461/.
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This work describes the investigation of optical ring or disk micro-resonator as elements in label-free biosensing devices. The use of polymeric materials for micro-resonator structures recently has been gain major interest multi disciplinary research since it allows rapid and straightforward fabrication process. The aim of the work described here was to develop an optical biosensor which operates within the visible range of λ = 500 – 800 nm based on micro-resonator principle by exploiting the SU-8 polymer material. This thesis is focused on fabrication procedures using the electron beam lithography (EBL) technology, device characterization, biological element immobilization and sensing experiments. Through the use of EBL technology, a double-cascaded gapless disk resonator (DDR) structure has been fabricated in order to significantly increase (composite) free-spectral range (FSR) to 10.0 nm from the 1.3 nm achievable with a single gapless disk resonator. The DDR structures also overcome the fabrication complexity of obtaining 50 nm gap spacing for bus waveguide to micro-resonator coupling. In order to build the device into a biological sensing platform, a biological immobilization protocol has been optimized by evaluating the degree of surface functionalization using fluorescence microscopy and X-ray photoelectron spectroscopy (XPS). Following this, to deliver the solutions required for sensing experiments, the device is integrated with a microfluidic channel system. In experiments using sucrose solutions, linear relationship between resonance wavelength shift and refractive index of the solution was achieved with the sensitivity of 12 nm/RIU. Further experiments were performed that used specific biotin-streptavidin antibody and multiple protein binding. These showed that the device was capable of detecting immobilised biomolecules. For example, the resonance wavelength shifted by 0.43 nm following streptavidin binding. Effort also has been devoted to perform experiments on combining the spectral absorption and resonance wavelength shift analysis since this device has a capability to operate in visible wavelength region, thus exploiting strongly coloured dyes. Here, using Dylight 649® labelled streptavidin, absorption at λ = 655 nm could be detected and was accompanied by a resonance wavelength shift of 0.261 nm. From the experiments in this thesis, the DDR device that operated within the visible wavelength region has exhibited the capability of resonance wavelength shift for label-free detection and absorption spectra analysis for optical biosensing.
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Dar, T. "Numerical characterisation of label free optical biosensors." Thesis, City University London, 2015. http://openaccess.city.ac.uk/13075/.
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There is a significant need for the development and use of numerical methods to simulate advance and complex optical biosensor structures. Finite Element Method (FEM) has been established as one of the most powerful and versatile numerical method and has been implemented in this thesis to characterize, analyse and optimise label-free optical biosensors for the detection of micron size biological objects like bacteria such as E.coli and nanometre size biomolecules such as antibody, nucleic acids and proteins. These sensors are all suitable for deep-probe sensing as large evanescent field can be excited in the sensing medium with substantial penetration depth achieved by techniques like Surface Plasmon Resonance (SPR) and sensor architectures based on nanowires and slot waveguides. This thesis presents three different architectures of label-free optical biosensors. First, a fiber optic surface plasmon resonance (SPR) biosensor for the detection of E.Coli is optically modeled by using the finite-element approach in conjunction with the perturbation technique which is computationally more efficient and can be used for waveguides with low or medium loss values. The same sensing architecture is used when surrounding index is varied from 1.30 -1.44 to cover most of the biological elements that are used in the biosensing applications. Second one is based on evanescent-wave guiding properties of nanowire waveguides a theoretical investigation of silica nanowires employing a wire assembled Mach-Zehnder structure to detect the presence of E.Coli is studied second. Finally, a slot-waveguide based micro-ring resonator is investigated for the detection of DNA Hybridization using H-field FEM based full-vector formulation. It is found that all of the numerical methods provide good agreement with the experimental sensitivities and detection limits.
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Pathak, Shantanu. "Resonant optical waveguide biosensor characterization." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3792.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains viii, 109 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 107-109).
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Scullion, Mark Gerard. "Slotted photonic crystal biosensors." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3405.
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Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them result in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This thesis presents a new platform for optical biosensors, namely slotted photonic crystals, which engender higher sensitivities due to their ability to confine, spatially and temporally, the peak of optical mode within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. High sensitivities were observed in smaller structures than most competing devices in the literature. Initial tests with cellular material for real applications was also performed, and shown to be of promise. In addition, groundwork to make an integrated device that includes the spectrometer function was also carried out showing that slotted photonic crystals themselves can be used for on-chip wavelength specific filtering and spectroscopy, whilst gas-free microvalves for automation were also developed. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.
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Carlsson, Jenny. "Interaction Studies in Complex Fluids with Optical Biosensors." Doctoral thesis, Linköpings universitet, Tillämpad Fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-14694.
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In this thesis interactions in complex fluids, such as serum and meat juice, were analysed with optical biosensor techniques. Panels of lectins immobilised on gold surfaces were used for investigation of differences in protein glycosylation pattern in sera and meat juices between various species. The present panel was also used for investigation of global glycosylation changes of serum proteins in type 1 diabetes patients. Biorecognition was evaluated with null ellipsometry and scanning ellipsometry combined with multivariate data analysis techniques (MVDA). Principal component analysis (PCA) showed that the lectin panel enabled discrimination between sera from the different species as well as for the different meat juices. The results also indicate that there is a measurable global alteration in glycosylation pattern of serum proteins in type 1 diabetic patients compared to healthy subjects. Using an artificial neuronal net (ANN), it was also possible to correctly categorise unknown serum samples into their respective class or group. The analytical potential of combining information from lectin panels with multivariate data analysis was thereby demonstrated. Also, a sensitive and specific method based on surface plasmon resonance (SPR) for detection of insulin autoantibodies (IAA) in serum samples from individuals at high risk of developing type 1 diabetes (T1D) has been developed. When measuring trace molecules, such as autoantibodies, in undiluted sera with label-free techniques like SPR, non-specific adsorption of matrix proteins to the sensor surface is often a problem, since it causes a signal that masks the analyte response. The developed method is an indirect competitive immunoassay designed to overcome these problems. Today, IAA is mainly measured in radio immunoassays (RIAs), which are time consuming and require radioactively labelled antigen. With our SPR-based immunoassay the overall assay time is reduced by a factor of >100 (from 4 days to 50 min), while sensitivity is maintained at a level comparable to that offered by RIA. Finally, the assay was used in a screening study of newly diagnosed type 1 diabetes patients and non-diabetic subjects.
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Schrenkhammer, Petra. "New optical biosensors for uric acid and glucose." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2008/993/.
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Chamorro, García Alejandro. "Electrochemical and optical nanomaterial-based biosensors for diagnostic applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/319692.
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La presente tesis describe el desarrollo de nuevos métodos de sensado basados en nuevas propiedades de nanomateriales aplicados en la detección de proteínas y ADN. El trabajo ha sido basado en dos plataformas de sensado: primero, electrodos serigrafiados de carbono (SPCEs). Estos electrodos fueron aplicados en un ensayo de detección por impedancia eléctrica de nanopartículas de oro (AuNPs). Del mismo modo, SPCE fueron adaptados mediante films de polythionina y nanopartículas de Iridio (IrOxNPs) para la detección de secuencias de ADN. La segunda plataforma utilizada fue basada en papel y tiene el formato de un inmunoensayo de flujo lateral (LFIA, del inglés lateral flow immunoassays). Esta plataforma se adaptó para la detección de una proteína específica Parathyroid like hormone (PTHLH) utilizando AuNPs como marcas, con el fin de obtener una nueva estrategia más simple, sin marcaje de isótopos radioactivos, menos costosa y más rápida. En el Capítulo 1 se da una visión general de las aplicaciones llevabas a cabo y mejoras aportadas por parte de nanomateriales en el campo de los biosensores, y las posibles aplicaciones en la detección de biomarcadores. En el Capítulo 2 se presentan los objetivos de la tesis. El uso de SPCE como plataforma para la detección de AuNPs mediante medidas de impedancia se presenta en el Capítulo 3 consiguiendo una mejor detección en comparación con métodos similares publicados para la detección de AuNPs. La técnica desarrollada es aplicada satisfactoriamente en la detección de AuNPs de diferente tamaño, y en un magnetoinmunoensayo utilizando AuNPs como marca para la detección de una proteína modelo. En el Capítulo 4, se presenta el trabajo relacionado con el desarrollo de nuevos sensores para la detección de DNA. El sistema está basado en la modificación de SPCEs mediante películas de un polímero y nanopartículas de óxido de iridio (IrOxNPs) sobre las cuales se inmovilizan secuencias de captura de DNA. La detección del ADN objetivo se consigue mediante medidas de impedancia eléctrica, basadas en el efecto de bloqueo del ADN hibridado para la difusión de un indicador redox a la superficie del electrodo. El biosensor resultante, que opera en modo libre de marcas, fue utilizado para la detección de secuencias de ADN específicas para el parásito de Leishmania. En el Capítulo 5 se presentan conclusiones generales y perspectivas futuras. En el Anexo A, se presenta el trabajo relacionado con las plataformas de papel para la detección de una proteína específica, PTHLH. El sistema de detección presentado es del tipo LFIA. La técnica desarrollada supone una alternativa menos costosa, más rápida y menos peligrosa a las técnicas disponibles actualmente. El límite de detección (LOD) conseguido está en el rango de ng mL-1 en muestras reales (medio de cultivo celular y lisado celulares). Además, se comprobó la compatibilidad del método desarrollado con suero humano utilizando suero humano con PTHLH añadido. En el Anexo B, se presenta el trabajo llevado a cabo en una estancia de investigación. En esta sección se presenta la fabricación de sensores electroquímicos de ADN (E-DNA) y basados en aptameros (E-Ab), y la aplicación de dicha tecnología en sensores serigrafiados de oro y en SPCE modificados con AuNPs. El Anexo C representa la investigación llevada a cabo como continuación de otra hecha anteriormente en nuestro grupo. Las condiciones y materiales encontrados previamente se aplicaron en la fabricación de una plataforma de nanocanales para la detección de una proteína secretada por células cultivadas directamente sobre la plataforma de sensado.This thesis describes the study and development of new biosensing approaches based on novel properties of nanomaterials for the detection of proteins and DNA. The work has been performed in basis of two sensing platforms: first platform, the carbon screen-printed electrodes (SPCEs), were used in a more sensitive detection of gold nanoparticles (AuNPs) through electric impedance measurements. Furthemore, the same platform (SPCE) was adapted through polythinione films and iridium oxide nanoparticles (IrOxNPs) for the detection of specific DNA sequences in a label free assay. The second platform, paper-based platforms in format of Flow Immunoassay (LFIA), using gold nanoparticles as labels is adapted for the detection of a specific protein, Parathyroid like Hormone (PTHLH), with the aim to find a new strategy for simpler, non-hazardous, cheaper and faster detection of the protein. In Chapter 1 a general overview of the application of nanomaterials for the improvement of biosensors and its application in the field of diagnostics and biomarkers detection is presented. In Chapter 2 the objectives of the thesis are presented. Use of SPCE as platform for detection of gold nanoparticles (AuNPs) through electric impedance measurements is presented in Chapter 3. The developed technique is successfully applied in the detection of AuNPs of different sizes, and in a magnetoimmnuoassay for the detection of a model protein using AuNPs as electrochemical labels. In Chapter 4, a novel biosensor for the detection of DNA is presented. The system is based in SPCE modified with polymer films and Iridium Oxide nanoparticles, where capturing DNA sequences have been immobilized. Detection of target DNA sequences is performed through electric impedance measurements, based in the blocking effect of the DNA against the diffusion of a redox indicator to the surface of the electrode. A label free immunoassay for detection of specific sequences of Leishmania parasite’s DNA is shown. In Chapter 5 general conclusions and future perspectives of the presented work are discussed. In Annex A the work related to the paper-based platform for protein detection is presented. In this annex, detection of a specific protein (parathyroid like hormone, PTHLH) through LFIA strips is described. The developed LFIA strips represent a cheaper, faster and non-hazardous alternative to current available systems for PTHLH detection. Limits of detection (LOD) in the range of ng mL-1 for PTHLH in real samples (cell culture media, cell lysates) are reported. Furthermore, the developed system is challenged using human serum spiked with PTHLH, proving the potential of the system to detect PTHLH In human serum. In Annex B the work carried out in a research stay is presented. In this section fabrication of electrochemical DNA (E-DNA), and electrochemical aptamer (E-Ab) biosensors is described. The aim of the work was focused on adapting the E-DNA and E-Ab technology to SPCE, using AuNPs as connecting platform between the thiol modified DNA and the SPCE. Annex C represents a research done as a continuation of a previous one done in the group related mostly to the study of compatible materials with interest to be used as cells growth platforms with interest in sensing. As continuation of this work, in Annex C the conditions and materials previously selected to grow cells are applied in a nanochannel platform for the detection of a protein secreted by the cells grown directly on the sensing platform.
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Chinowsky, Timothy Mark. "Optical multisensors based on surface plasmon resonance /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5857.
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Asiri, Hamoudi. "Fabtrication of Surface Plasmon Biosensors in CYTOP." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23286.
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This thesis describes work carried out on the research, development and implementation of new processes for the fabrication of surface plasmon waveguide biosensors. Fabrication of surface plasmon resonance (SPR) based waveguides embedded in a thick CYTOP cladding with the incorporation of fluidic channels was achieved with improved quality and operability compared to previous attempts. The fabrication flow was modified in key areas including lithography for feature definition, gold evaporation and the upper cladding deposition procedure. The combined result yielded devices with sharper resolution of waveguides, gold surfaces with minimal aberrations, reduced surface roughness and minimization of waveguide deformation due to reduction of solvent diffusion into the lower cladding. The fabricated waveguides consisted of a thin, 35 nm, patterned gold film, embedded in a thick, 18 µm, CYTOP fluoroploymer cladding. The gold devices were exposed by O2 plasma etching through the upper cladding to form fluidic channels for the facilitation of flow of an index matched sensing medium. Optical and physical characterization of devices revealed structures of significantly improved quality over previous attempts, rendering the platform competitive for biosensing applications.
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Blyth, David John. "Optical biosensing using sol-gel technology." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338063.
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El-Dweik, Majed. "Optical glucose nanobiosensor encapsulated in erythrocytes." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4672.
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Thesis (Ph.D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 23, 2009) Vita. Includes bibliographical references.
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Psoma, Sotiria D. "Fluorescence-based optical biosensors for clinical and environmental applications." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/3917.
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The aim of this thesis was to investigate the feasibility of simultaneous utilisation of pH and oxygen-dependent fluorescent indicators for the development of a novel fibre-optical fluorescence-based bio sensor. This approach would be used to measure simultaneously changes in the two indicator species generated by a single enzyme-catalysed reaction in response to one analyte where both the indicators and the enzyme are immobilised in the same sol-gel matrix, and to offer more accurate and reliable results using this portable optical biosensor in the clinical and environmental fields. HPTS (1-hydroxypyrene-3,6,8-trisulfonic acid) and tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate, respectively, were used as the target fluorescent indicators; these two indicators had no cross sensitivity separate or in the same solution and well-separated emission bands at 510 nm and 610 mn, respectively. The catalytic oxidation of glucose by the enzyme glucose oxidase was initially investigated using the two indicators, and subsequently the same principle was applied in other biocatalysed oxidations such as of lactate, xanthine and phenol. Substrate concentration was assessed by simultaneously measuring two parameters: oxygen consumption, through the reduction of the fluorescence intensity of tris(2,2'-bipyridyl) ruthenium(II) chloride hexahydrate; and the production of acid, through pH changes affecting the fluorescence intensity of HPTS.A thorough spectroscopic study of the enzymatic oxidation of glucose was performed using glucose oxidase in solution in a cuvette, in the presence of both indicators. A number of combinations of wavelengths of the indicators for excitation and fluorescence were utilised in order to establish calibration curves with the optimum performance for glucose detection in the diabetic range. Similarly results were taken from the kinetic studies of lactate oxidase, xanthine oxidase and polyphenol oxidase for the detection of lactate and xanthine in blood and phenol in water at ppb-levels, using the above principle. The application and characterisation of immobilisation techniques for the fluorescence-based blood-glucose b iosenor were carried out. The advantages of the microcapsulation sol-gel method over conventional immobilisation techniques for application in an optical biosensor, were elucidated and this immobilisation technique was implemented for glucose and phenol detection. Finally, additional solution studies were conducted and used to evaluate the implementation and performance of the above method when used for the detection and measurement of glucose concentration in biological samples such as human serum.
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Sweeney, Robin Emily, and Robin Emily Sweeney. "Biosensors for Blood and Infection Analysis." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626360.
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Three major topics will be discussed in this dissertation. The first is an optical biosensor for specific diagnosis of bacterial skin and wound infection, followed by a paper microfluidic assay and accompanying monitoring device for monitoring blood coagulation and determining patient-specific heparin and protamine dosing. The final work to be discussed is ongoing work involving the detection of circulating tumor cells (CTCs) using a paper microfluidic detection platform.
All of these works involve the development of biosensors for the simultaneous advancement and simplification of diagnosis and analysis of blood and bacterial infection. The aims of each of these projects included significantly decreasing the time to diagnosis and decreasing the reagents, laboratory space, personnel, and other resources needed for detection and diagnosis.
The first works are focused on the design, development, and testing of an optical biosensor for the immediate detection of bacterial skin and wound infection, including diagnosing the specific species of bacteria responsible for the infection. The optical biosensor developed allows for diagnosis of a bacterial infection on skin or in a wound in as little as three seconds, in a contact-free, reagent-free manner.
The second work focused on the design, development, and testing of a paper microfluidic assay and accompanying Raspberry Pi-based monitoring device for use before, during, and after surgeries requiring the use of cardiopulmonary bypass. The assay monitors the extent of blood coagulation of a whole blood sample and determines patient-specific dose response curves of an anticoagulant and its reversal agent.
The final work discussed focuses on developing a paper microfluidic assay for the detection of CTCs from whole blood samples. The goal of this work is to detect multiple morphologies of CTCs from whole blood samples to provide insight on patient prognosis in a rapid, low resource manner.
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Cornell, Timothy Allen. "Fabrication of resonant optical waveguide biosensors using electron gun depositions." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4272.
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Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains iv, 94 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 93-94).
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Cho, Soohee, and Soohee Cho. "Smartphone-Based Optical Detection of Diagnostic Biosensors on Microfluidic Platforms." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625604.
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Diagnostic biosensors are on the rise in the global market due to the increasing prevalence of diseases. Specifically, the point-of-care segment has made great strides due to the improvement of biosensors' user-friendliness, simplicity, and clinical capabilities in the comfort of one's home. Although there are conventional diagnostic techniques, they are mutually time-consuming, costly, and labor-intensive. Not to mention, they are primarily dependent on bench-top or large immovable equipment. The widespread availability of smartphones has potentiated optical biosensors towards delivery of rapid and point-of-care diagnostic biosensors. Due to the affordability and user-friendliness of smartphones, smartphone-based biosensors may become ubiquitously available. Additionally, microfluidic platforms possess small footprints and portability towards development of true point-of-care and real-time diagnostic biosensors.
In this dissertation, development of multiple diagnostic biosensors on microfluidic platforms is discussed. Diagnostic biosensors equipped with a smartphone-based optical detection show great promise of bringing clinical and bench-top laboratory capabilities for the convenience of the user, with reduced time, costs, and labor requirements. The widespread availability of point-of-care and real-time diagnostic biosensors may show promise in securing global health.
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Rivas, Torcates Lourdes. "Electrochemical and optical nanoparticlebased biosensors for point-of-care applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/285610.
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Thomas, F. C. "Thin film oxygen optical sensors and their use as biosensors." Thesis, Swansea University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639224.
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The purpose of the thesis was to develop a sensitive oxygen optical sensor, which, when coupled with an enzymatic reaction would lead to the creation of useful optical biosensors for the biochemical analytes hydrogen peroxide and glucose. Chapter 3 is an account of work in which a [Ru(dpp)3 2+(Ph4B-)2]-based oxygen optical sensor, immobilized in silicone rubber, was developed and fully characterised. The sensor was extremely sensitive and stable towards oxygen compared with previous literature findings. The sensitivity of the oxygen sensors was temperature independent, but the response and recovery times decreased with increasing temperature. Chapter 4 gives results from an investigation into some of the factors controlling the sensitivity of a series of [Ru(L)3 2+(Ph4B-)2]-based oxygen optical sensors immobilized in cellulose acetate. The sensitivity was found to vary according to the lumophore's lifetime and the amount of plasticizer used in the formulation. The sensitivity of the oxygen sensor increased with longer lumophore lifetime and with plasticizer volume. Chapter 5 provides results from a study of an analogous, highly sensitive optical sensor, i.e. [Ru(dpp)3 2+(Ph4B-)2] immobilized in cellulose acetate butyrate and plasticized by tributyl phosphate which was coupled with an enzymatic reaction to produce a hydrogen peroxide optical biosensor. This biosensor was found to be more sensitive than those previously reported in the literature, due to the increased activity of the catalase enzyme as measured by Michaelis kinetics. Chapter 6 gives an account of the development and characterisation of a glucose biosensor. The biosensor sensitivity could be tuned for different applications by varying the amount of glucose oxidise used in the formulation. The activity, as measured by Michaelis kinetics was largely independent of temperature.
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Sapsford, Kim Elizabeth. "The development of optical biosensors for nitrogen oxyanions using metalloproteins." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327497.
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Aylott, Jonathan William. "The development of optical biosensors using sol-gel immobilised metalloproteins." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389226.
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Beffara, Flavien. "SERS biosensors based on special optical fibers for clinical diagnosis." Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0009.
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Malgré d'importantes percées dans le domaine de la biodétection, nous avons toujours besoin de nouveaux capteurs qui faciliteraient la détection précoce de maladies graves comme le cancer. La biopsie tissulaire classique reste la référence dans de nombreux cas. Bien que cette approche ait montré son potentiel, elle reste invasive pour les patients et les techniques de détection sont fastidieuses ou manquent de sensibilité pour détecter la maladie à un stade précoce. La spectroscopie Raman a démontré son intérêt pour la biodétection. Sa capacité à caractériser la nature chimique, la structure et l'orientation d'un analyte, en fait un candidat idéal. Les pics Raman très nets d'une molécule peuvent être considérés comme une véritable empreinte digitale. Malheureusement, le signal Raman diffusé est extrêmement faible. Cette limitation a été surmontée par la spectroscopie Raman exaltée de surface (SERS), car elle augmente considérablement le signal Raman diffusé tout en maintenant la largeur des pics du spectre d'une molécule. Malheureusement, la plupart des substrats SERS actuels sont soit des surfaces métalliques nano-rugueuses en 2D soit des nanoparticules colloïdales, qui manquent de sensibilité et de fiabilité dans les mesures avec une faible répétabilité et reproductibilité des données. Ces dernières années, des fibres optiques spéciales ont été utilisées comme plateformes SERS. Elles comportent des trous qui s'étendent sur toute leur longueur. Ces trous permettent d'incorporer l'analyte à l'intérieur de la fibre. Ainsi, une telle plate-forme représente une alternative prometteuse aux substrats plans puisque l'analyte et la lumière d'excitation peuvent interagir sur une plus grande longueur à l'intérieur des fibres. De plus, les fibres optiques sont très flexibles, compactes, et permettent un guidage de la lumière à faible perte. Par conséquent, ces capteurs à fibres présentent à la fois les capacités de détection exceptionnelles du SERS, les avantages des fibres optiques et une sensibilité et une fiabilité améliorées. Dans ce manuscrit, nous visons à créer une plateforme de biodétection qui pourrait être utilisée dans un cadre clinique. Pour cela, nous proposons d'optimiser les caractéristiques d'une topologie de fibre déjà existante. Cela nous permet d'augmenter sa sensibilité tout en améliorant sa fiabilité et sa facilité d’utilisation. Grâce à ce capteur amélioré, nous avons pu pour la première fois détecter le biomarqueur du cancer de l'ovaire dans les fluides de kystes cliniques, ce qui nous a permis de différencier le stade du cancer. Par la suite, nous proposons une nouvelle topologie de fibre, spécifiquement conçue pour augmenter encore la sensibilité des sondes à fibre basées sur le SERS. Cette amélioration est réalisée en augmentant la surface d'interaction par rapport aux sondes à fibre standard. Pour cela, le diamètre du noyau est considérablement augmenté et la quantité de lumière qui interagit avec l'analyte est contrôlée avec précision. Nous envisageons que de tels capteurs à fibres fonctionnalisés puissent être incorporés à l'intérieur d'une aiguille de biopsie afin de créer un capteur deux-en-un pour la collecte et l’analyse de fluides corporels. Les limitations associées aux aiguilles de biopsie actuelles, qui exigent une collecte et une analyse des échantillons en deux étapes, pourraient ainsi être surmontéesDespite important breakthroughs in biosensing, we are still in need of new sensors that would facilitate the early detection of severe diseases such as cancer. Classical tissue biopsy remains the gold standard in many cases. Although this approach has shown its potential, it remains invasive for the patients and the detection techniques are either tedious or lack the sensitivity to detect the disease at an early stage. Raman spectroscopy has demonstrated its interests for biosensing. Its ability to characterize the chemical nature, structure and the orientation of an analyte makes it an ideal candidate. The sharp Raman peaks of a molecule can be seen as a true fingerprint. Regrettably, Raman scattered signal is extremely weak. This limitation was overcome by surface enhanced Raman spectroscopy (SERS), since it drastically increases the Raman scattered signal while maintaining the sharp peak of the fingerprint spectrum of a molecule. Unfortunately, most of the current SERS substrates are 2D nano-roughened metal surfaces or colloidal nanoparticles, which lack the sensitivity and reliability in measurement with poor repeatability and reproducibility in the data. In the recent years, special optical fibers have been used as SERS platforms. They feature holes that run along their entire length. These holes allow for the analyte to be incorporated inside the fiber. Thus, such platform represents a promising alternative to planar substrates since the analyte and the excitation light can interact for longer length inside the fibers. In addition, optical fibers are very flexible, compact and allow for low-loss light guiding. Therefore, such fiber sensors exhibit the outstanding detection abilities of SERS, the advantages of optical fibers and improved sensitivity and reliability. In this manuscript, we aim to create a biosensing platform that could be routinely used in a clinical setting. For that, we propose to optimize the features of an already reported fiber topology. This allows us to increase its sensitivity while simultaneously improving its reliability and practicability. With this improved sensor, for the first time, we could detect the biomarker for ovarian cancer in clinical cyst fluids, which allowed us to differentiate the stage of the cancer. Subsequently, we propose a novel fiber topology, specifically designed to further increase the sensitivity of SERS-based fiber probes. This is achieved by increasing the surface of interaction compared to standard fiber sensors. For that, the core diameter is significantly increased and the amount of light that interacts with the analyte is precisely controlled. We envision that such functionalized fiber sensors could be incorporated inside a biopsy needle to create a two-in-one sensor for body fluid collection and readout that can eventually overcome the limitations associated with existing biopsy needle platforms, which demands for two-step sample collection and readout
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Samudrala, Pavan Kumar. "Alumina waveguide characterization and SPARROW biosensor modeling." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4841.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains vii, 85 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-72).
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Poloju, Praneetha. "Fabrication and functional analysis of SPARROW biosensor." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5374.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains viii, 90 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 74-76).
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Barnes, Robert David Frazer. "Diffraction gratings as a platform for overlayer detection and representation." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319553.
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Ruano-Lopez, Jesus M. "Optical devices for biochemical sensing in flame hydrolysis deposited glass." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368575.
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Stengel, Gudrun. "Real time monitoring of DNA hybridization and replication using optical and acoustic biosensors." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971304572.
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Sun, Kailiang. "Fluorescence based optical sensor for protein detection." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2010r/ksun.pdf.
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Quantrill, Nigel Stuart Michael. "Optical fluoroassays based on substrate induced quenching." Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/10428.
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The
recently proposed bioassay procedure that is based on the substrate induced
quenching (SIQ) of an indicator fluorescence for the measurement of analyte
concentrations is evaluated. In this type of assay a enzynatic reaction and a
fluorescence
quenching interaction are coupled together. Typically, an appropriate
dehydrogenase enzyme reduces or oxidises the nicotinamide adenine dinucleotide
cofactor. The
change in the concentration of NADH results in variations in the excited
fluorophore population as observed through fluorescence intensity. This latter aspect is
used to monitor substrate (analyte) concentrations.
Results on the
investigation of the substrate induced quenching bioassay method and
possibilities of using it as the basis of (i) a novel enzyme bioassay technique and (ii) a
novel
bioprobe format are presented. Ethanol was chosen as the model analyte, and a
new
assay procedure for its measurement was developed.
A
generic theoretical relation is discussed for the observed assay kinetics of substrate
induced
quenching (SIQ) and a model is described that includes the effects due to
dynamic/static quenching of the fluorophore by either the enzyme substrate or product.
The
validity of the derived model is shown by comparison with experimental results for a
SIQ based ethanol assay. The option of running the dehydrogenase reaction so as to
consume NADH rather than
generate it is also investigated. In order to demonstrate this
approach acetaldehyde was chosen as the model analyte, and a assay procedure for its
measurement was
developed.
The
potential of the SIQ technique for incorporation into biosensor based upon a
'reservoir' format was demonstrated through the development of custom optical
instrumentation and resevoir flowcell. Applicability of the SIQ technique to other
biosensor formats such as flow-injection analysis and 'dry reagent' technology is
discussed.
The overall
applicability of the SIQ technique is assessed through the generation of a
number of SIQ assays on the following substrates: ethanol, glucose, glucose-6-
phosphate, L-glutamic acid, isocitric acid, acetaldehyde, pyruvic acid, ot-ketoglutaric
acid, and oxalacetic acid.
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Cheung, Sin Man. "Development of optical chemosensors for cation sensing." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/771.
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Dante, Stefania. "All-optical phase modulation for advanced interferometric point-of-care biosensors." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285191.
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Durante las últimas décadas un gran número de trabajos se han centrado en la implementación de plataformas lab-on-chip compactas y de alta sensibilidad, para una amplia gama de aplicaciones descentralizadas. Los dispositivos basados en óptica integrada se han revelado como candidatos prometedores, ya que combinan una alta sensibilidad en ensayos directos sin marcadores, con una fabricación de bajo coste a través de la tecnología estandar microelectrónica, permitiendo su producción en masa. En particular las configuraciones interferométricas han demonstrado las prestaciones superiores, en términos de resolución y límite de detección, en comparación con otros dispositivos de óptica integrada como los resonadores o las redes de difracción. Sin embargo, la complejidad en la interpretación de su señal de respuesta, consecuencia de su periodicidad con las variaciones de fase, dificulta su comercialización y su adopción en la práctica clínica.
Para resolver las limitaciones de los biosensores interferométricos tradicionales y permitir una integración completa en una plataforma lab-on-chip, se ha estudiado teórica y experimentalmente un nuevo método para la linearización de la señal de salida. Este método se basa en la variación de la longitud de onda de emisión de la fuente láser, que se traduce en una modulación de fase. A fin de mantener una plataforma compacta y rentable, la modulación se introduce aprovechando la dependencia entre la longitud de onda y la potencia de los diodos láser comerciales. El método se ha aplicado a dos plataformas, los interferometros Mach-Zehnder y de guía de onda bimodal, desarrollados en el grupo de investigación donde se ha realizado este trabajo. Los sensores interferométricos modulados en longitud de onda permiten una lectura directa en tiempo real y sin ambigüedades, con una alta sensibilidad tal y como requieren las aplicaciones biosensoras en ámbitos reales.During the last decades impressive efforts have been devoted to the implementation of compact and highly sensitive lab-on-chip platforms for a wide range of decentralized applications. Among optical devices, those based on integrated optics have been underlined as promising candidates since they combine a high sensitivity in a label-free approach with a cost-effective fabrication through standard Si microfabrication technology, rendering in potential mass production. In particular interferometric arrangements have shown superior performances in terms of resolution and limits of detection compared to other integrated optics solutions as resonators or grating structures. However the complexity of their read-out, consequence of the periodicity of the output signal with the phase variation, still hinders their successful commercialization and adoption in the clinical practice. In order to solve the limitations of standard integrated interferometric biosensors and to allow a complete integration onto a lab-on-chip platform, an innovative method for linearization of the interferometric output is theoretically and experimentally analyzed. The proposed phase modulation system is based on tuning of the emission wavelength of the laser source. In order to keep a compact and cost-effective platform, the wavelength modulation is introduced by taking advantage of the power-wavelength dependence of commercial laser diodes. Thanks to our research Group experience in the design and fabrication of integrated optical biosensors, two different platforms have been analyzed along this Thesis, namely the well-known Mach-Zehnder interferometer and the recently proposed Bimodal Waveguide interferometric biosensors. The wavelength modulated interferometric biosensors allow a direct, unambiguous, highly sensitive real-time read-out, as required by real biosensing applications.
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Macias, Sotuela Gerard. "Nanostructural Engineering of Optical Interferometric Biosensors Based on Nanoporous Anodic Alumina." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/292246.
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Aquesta tesi doctoral presenta els resultats d'estudis en l'efecte de les característiques nanoestructurals en biosensors òptics d'interferència basats en alúmina anòdica nanoporosa (NAA). Els biosensors òptics són dispositius altament sensibles capaços de detectar selectivament analits químics o bioquímics monitoritzant la interacció bioquímica entre un receptor d'origen biològic i l'analit en qüestió. En aquest treball s'han presentat les tècniques disponibles per al biosensat i els principis de biosensat, així com els procediments més comuns per a la fabricació de NAA juntament amb les corbes de calibració requerides per a la seva fabricació i també, la caracterització estructural i òptica d'aquest material. Dues estructures òptiques interferomètriques diferents s'han estudiat i optimitzat: la monocapa i la doble capa. Els resultats mostren com, en general, diàmetres de porus grans i capes fines resulten en un millor funcionament del sensor. A més, l'interferòmetre de doble capa presentat aquí consta d'una capa de referència per a l'autocorrecció de les desviacions ambientals gràcies a la seva arquitectura capaç de separar les proteïnes i el dissolvent. Finalment, s'ha presentat una estructura fotònica més complexa: el rugate filter. Els experiments preliminars mostren resultats prometedors amb sensibilitats similars a la d'altres mètodes i permet noves formes de detecció, com ara la colorimetria.sta tesis doctoral presenta los resultados de estudios sobre el efecto de las características nanoestructurales en biosensores ópticos de interferencia basados en alúmina anódica nanoporosa (NAA). Los biosensores ópticos son dispositivos altamente sensibles capaces de detectar selectivamente analitos químicos o bioquímicos monitorizando la interacción bioquímica entre un receptor de origen biológico y el analito en cuestión. En este trabajo se han presentado las técnicas disponibles para el biosensado y los principios del biosensado, así como los procedimientos más comunes para la fabricación de NAA juntamente con las curvas de calibración necesarias para su fabricación y también la caracterización estructural y óptica de este material. Dos estructuras ópticas interferométricas distintas se han estudiado y optimizado: la monocapa y la doble capa. Los resultados muestran como, en general, los diámetros de poro grandes y capas finas resultan en un mejor funcionamiento del sensor. Además, el interferómetro de doble capa presentado aquí consta de una capa de referencia para la autocorrección de las desviaciones ambientales gracias a su arquitectura capaz de separar las proteínas del disolvente. Finalmente, se ha presentado una estructura fotónica más compleja: el rugate filter. Los experimentos preliminares muestran resultados prometedores con sensibilidades similares a las de otros métodos y permiten nuevas formas de detección, como la colorimetria.
This Ph.D. thesis presents the results of studies on the effect of nanostructural features of interferometric optical biosensors based on nanoporous anodic alumina (NAA). Optical biosensors are highly sensitive devices capable of selective detection of chemical or biochemical species by monitoring the biochemical interaction between a biological receptor and the target analyte. In this work, a survey of the different biosensing techniques has been carried out and the principles of biosensing have been explained, as well as the common procedures for the fabrication of NAA along with the calibration curves required for its fabrication. Also structural and optical characterization of this material is presented. Two different optical interferometric biosensing devices have been studied and optimized: the monolayer and the double layer. Moreover, the proposed double-layer interferometer has an integrated reference channel for self-correction of the environmental drifts thanks to its size exclusion architechture. Finally, a more complex photonic structure has been introduced: the rugate filter. The preliminary experiments show promising results with sensitivities similar to those of other methods and allow new detection techniques, such as colorimetry.
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Hölzel, Sara Sibylle [Verfasser]. "Group III-Nitride Nanowires as Multifunctional Optical Biosensors / Sara Sibylle Hölzel." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1173615059/34.
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Hölzel, Sara [Verfasser]. "Group III-Nitride Nanowires as Multifunctional Optical Biosensors / Sara Sibylle Hölzel." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1173615059/34.
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Edwards, Paul. "The use of optical biosensors for kinetic analysis : a critical appraisal." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7472.
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Carloni, Adolfo. "A novel optical chip for affinity biosensors based on fluorescence anisotropy." Thesis, Cranfield University, 2008. http://dspace.lib.cranfield.ac.uk/handle/1826/3168.
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The subject of this thesis relates to the realisation of a novel biochip for sensors based on optical principles. In particular, affinity biosensors for antigens (IgG/anti-IgG), for a transcription factor, and for mRNA were studied and developed. The interrogation of the biosensors implied the development of a novel and innovative optical platform based on fluorescence which was designed, implemented and thoroughly characterised. The biosensors developed were integrated within an optical biochip connected to an innovative platform. The optical biochip was fabricated from polymethylmethacrylate (PMMA) formed by two pieces of PMMA complementary shaped in order to obtain four micro-channels. The lower part included the micro-channels and the inlet and outlet for the fluidic, while the sensing biolayer was immobilised on the upper part. The optical signal comprised the fluorescence emitted by the layer, which was anisotropically coupled to the cover and suitably guided by the chip. Several chemical treatments of the surface were investigated to obtain the most effective distribution of carboxylic groups for the covalent immobilisation of antibodies. Deposition of the polymers, in particular by Langmuir-Blodgett method, can enhance the performances of the chip going through lower detection limits. The potential of the optical chip as a biosensor was investigated in depth by means of a direct IgG/anti-IgG interaction carried out inside the flow channels. Following this, bioassays for the determination of the NF-kB transcription factor and for the mRNA that codifies for MGMT protein were implemented on the optical platform. The development and characterisation of the biosensors, the identification of the protocol for the bioassays and the design and characterisation of the optical platform were performed at the Institute of Physics Applied Carrara of National Research Council (IFAC-CNR), Firenze, Italy. The research devoted to the development of biosensing surfaces for the realisation of affinity biosensors able to detect and quantify antigens, transcription factors and RNA sequences were carried out at the laboratories of the Institute of Clinical Physiology of National Research Council (IFC-CNR), in Pisa, Italy. Langmuir-Blodgett deposition of polymers, Atomic Force Microscopy imaging and further fluorescence measurements of proteins covalently bound on the surfaces were performed at Cranfield University in Silsoe, England. The overall project starts from a first characterisation of the optical system, and comprehend the enhanced optimisation of the biochip performances until the realisation of the biosensors previously mentioned.
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Peláez, Gutiérrez Enelia Cristina. "Nanoplasmonic biosensors for clinical diagnosis, drug monitoring and therapeutic follow-up." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/672028.
Full textAbstract:
Aquesta tesi doctoral té com a objectiu el desenvolupament de diversos biosensors que operen sense necessitat de marcatge addicional basats en dispositius plasmònics òptics per a la detecció directa de medicaments o biomarcadors relacionats amb diferents malalties i que són analitzats directament en mostres humanes com plasma, sèrum, orina o esput. Aquests dispositius biosensors ofereixen un sens fi de beneficis com és la seva alta sensibilitat, facilitat d’operació, l’obtenció de dades quantitatives, detecció sense marcatge en temps real, i comunament només necessiten d’un petit volum de mostra. Tot això converteix els biosensors plasmònics en eines analítiques molt adequades per al diagnòstic de malalties, el control de la medicació o el seguiment de teràpies personalitzades. El nostre grup d’investigació ha demostrat amb èxit la implementació de biosensors òptics basats en plasmònica i en fotònica de silici, inclòs el desenvolupament complet de bioaplicaciones, el que ha aplanat el camí de la seva futura transferència tecnològica per a la seva implementació com a dispositius Point-of-Care ( POC). Els biosensors desenvolupats en aquesta Tesi inclouen la seva optimització i validació completa amb mostres reals, exemplificant alguns desafiaments clínics en els quals aquests biosensors plasmònics poden superar importants limitacions de les tècniques d’anàlisi convencionals actuals, mostrant el seu potencial i versatilitat com a futurs dispositius POC per ser usats en les unitats d’atenció primària en salut o fins i tot en l’entorn domèstic per al propi autocontrol per part dels pacients.
La tesi està organitzada en sis capítols. El capítol 1 conté la introducció dels conceptes bàsics i l’estat de l’art sobre els avenços actuals en les tècniques de diagnòstic i control de malalties i / o teràpies i el paper que exerceixen els biosensors per millorar-los. El capítol 2 inclou una descripció detallada de les plataformes biosensoras emprades i una descripció general dels processos metodològics. El Capítol 3 descriu el desenvolupament d’un dispositiu nanoplasmónico per al control terapèutic de l’medicament acenocumarol, un anticoagulant comunament administrat directament en plasma humà. El Capítol 4 es centra en el desenvolupament d’un biosensor plasmónico que serveixi com a control de la dieta lliure de gluten que han de portar els pacients celíacs. El Capítol 5 descriu les estratègies desenvolupades per a la detecció de dos biomarcadors per al diagnòstic primerenc de tuberculosi en mostres d’esput. Finalment, el Capítol 6 explora la detecció de quatre autoanticossos específics associats amb l’aparició de l’tumor directament en el sèrum humà com biomarcadors potencials per al diagnòstic primerenc de el càncer colorectal.Esta Tesis Doctoral tiene como objetivo el desarrollo de diversos biosensores que operan sin necesidad de marcaje adicional basados en dispositivos plasmónicos ópticos para la detección directa de medicamentos o biomarcadores relacionados con diferentes enfermedades y que son analizados directamente en muestras humanas como plasma, suero, orina o esputo. Estos dispositivos biosensores ofrecen un sinnúmero de beneficios como es su alta sensibilidad, facilidad de operación, la obtención de datos cuantitativos, detección sin marcaje en tiempo real, y comúnmente sólo necesitan de un pequeño volumen de muestra. Todo esto convierte a los biosensores plasmónicos en herramientas analíticas muy adecuadas para el diagnóstico de enfermedades, el control de la medicación o el seguimiento de terapias personalizadas. Nuestro grupo de investigación ha demostrado exitosamente la implementación de biosensores ópticos basados en plasmónica y en fotónica de silicio, incluido el desarrollo completo de bioaplicaciones, lo que ha allanado el camino de su futura transferencia tecnológica para su implementación como dispositivos Point-of-Care (POC). Los biosensores desarrollados en esta Tesis incluyen su optimización y validación completa con muestras reales, ejemplificando algunos desafíos clínicos en los que dichos biosensores plasmónicos pueden superar importantes limitaciones de las técnicas de análisis convencionales actuales, mostrando su potencial y versatilidad como futuros dispositivos POC para ser usados en las unidades de atención primaria en salud o incluso en el entorno doméstico para el propio autocontrol por parte de los pacientes. La tesis está organizada en seis capítulos. El Capítulo 1 contiene la introducción de los conceptos básicos y el estado del arte sobre los avances actuales en las técnicas de diagnóstico y control de enfermedades y/o terapias y el papel que desempeñan los biosensores para mejorarlos. El Capítulo 2 incluye una descripción detallada de las plataformas biosensoras empleadas y una descripción general de los procesos metodológicos. El Capítulo 3 describe el desarrollo de un dispositivo nanoplasmónico para el control terapéutico del medicamento acenocumarol, un anticoagulante comúnmente administrado directamente en plasma humano. El Capítulo 4 se centra en el desarrollo de un biosensor plasmónico que sirva como control de la dieta libre de gluten que deben llevar los pacientes celíacos. El Capítulo 5 describe las estrategias desarrolladas para la detección de dos biomarcadores para el diagnóstico temprano de tuberculosis en muestras de esputo. Finalmente, el Capítulo 6 explora la detección de cuatro autoanticuerpos específicos asociados con la aparición del tumor directamente en el suero humano como biomarcadores potenciales para el diagnóstico temprano del cáncer colorrectal.
This Doctoral Thesis aims to the development of several label-free biosensing analytical strategies integrated within optical plasmonic devices for the direct detection of drugs or biomarkers related to different diseases in biological samples such as plasma, serum, urine, and sputum. These biosensor devices offer several benefits like their high sensitivity, ease of operation, quantitative data, label-free operation, and real-time detection, and commonly require a small sample volume. All this turn plasmonic biosensors into well-suited analytical tools for diagnosing diseases, monitoring medication, or for personalized therapies follow-up. Our research group has extensively demonstrated the successful conjunction of novel in-house optical biosensor configurations (like plasmonic and photonic-based designs) with the full demonstrations of bioapplications, which has paved the way for their potential technological transfer as Point-of-Care devices (POC) for clinical diagnostics. The biosensor assays here implemented, which include their full optimization and validation with real samples, exemplify clinical challenges where such biosensors can overcome limitations of current conventional analytical techniques. The results show the potential and versatility that plasmonic biosensors can offer as future POC devices placed in primary healthcare units or even in the household environment for patients’ self-monitoring. This thesis is organized into six chapters. Chapter 1 is the introductory one, which explains the basic concepts and the state of the art of the current advances in diagnosis and monitoring techniques of diseases and/or therapies and the role of biosensors to improve them. Chapter 2 includes a detailed description of the biosensor platforms employed and a general description of the methodological processes. Chapter 3 is related to the development of a nanoplasmonic device for the therapeutic monitoring of the drug acenocoumarol, a commonly administered anticoagulant, directly in human plasma. Chapter 4 focuses on the implementation of a plasmonic biosensor that monitors the gluten-free diet in urine in celiac patients. Chapter 5 describes the biosensing strategies developed for the detection of two biomarkers for the early diagnosis of tuberculosis in sputum samples. Finally, Chapter 6 explores the detection of four specific autoantibodies associated with the tumor onset directly in human serum as potential biomarkers for the early detection of colorectal cancer.
Universitat Autònoma de Barcelona. Programa de Doctorat en Química
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Wang, Chun-Wei. "Quantitative protein detection in serum samples using fiber-optic biosensors." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/wang.pdf.
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Tsargorodska, Anna. "Research and development in optical biosensors for determination of toxic environmental pollutants." Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20458/.
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The detection of pollutants (such as toxins, heavy metal ions, and pesticides) in water and food plays an important role in human health and safety regulations. Different optical biosensing techniques enabling the monitoring of these compounds were chosen for this study. Low molecular weight (LMW) environmental toxins, such as simazine, atrazine, nonylphenol and T-2 mycotoxin were registered with the methods of surface plasmon resonance (SPR) and the recently developed total internal reflection ellipsometry (TIRE). The immune assay approach was exploited for in situ registration of the above toxins with specific antibodies immobilized onto a gold surface via a polyelectrolyte layer using electrostatic self-assembly (ESA) technique. TIRE showed a higher sensitivity than the SPR technique. The obtained responses of the TIRE method were higher than estimated for the immune binding of single molecules of nonylphenol or T-2 mycotoxin. The mechanism of the binding of large aggregates of these toxins to respective antibodies was suggested as a possible reason for this. The formation of large molecular aggregates of toxin molecules on the surface was later proven by the AFM study. The prototype of the portable sensor array device for water pollution monitoring was based on a SiO[2]/Si[3]n[4] planar waveguide with a sensing window coated with ESA film containing pH sensitive organic chromophore molecules and different enzymes (namely, urease, acetyl- and butyryl-cholinesterase) adsorbed on a disposable nylon membrane. The sensor was capable of registration of enzyme reactions as well as their inhibition by traces of some typical water pollutants, such as heavy metal ions Cd[2+], Pb[2+], and Ni[2+], and pesticides imidacloprid and DVDP over a wide range of concentrations (from 1000 ppb down to 0.1 ppb). A portable prototype sensor array device comprises a fan-beam laser diode, a semi-cylindrical lens, a planar waveguide with a three-channel cell attached, and a CCD array photodetector. Dedicated software was developed for CCD image processing and further data analysis with an artificial neural network. The large internal surface area within a small volume, efficient room-temperature visible photoluminescence and biocompatibility of porous silicon (PS) has stimulated recent interest in its applications for sensor development. The method of spectroscopic ellipsometry was applied to study in situ the adsorption of bovine serum albumin (BSA) into PS. The porosity and amount of adsorbed BSA were determined by fitting the ellipsometric data to the Bruggeman effective medium approximation model. The presence of intermediate adsorbed layers of polyelectrolytes was found to increase protein adsorption.
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Fedorenko, Viktoriia. "Atomic layer deposition on three dimensional silicon substrates for optical biosensors applications." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT183/document.
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Ce manuscrit de thèse présente les recherches et les applications potentielles en tant que plate-forme (bio) capteur des couches minces conformes de ZnO et / ou Al2O3 / ZnO nanolaminates, déposées par dépôt de couche atomique (ALD) sur les différents substrats. Tout d'abord, une étude des propriétés optiques des films minces ZnO (20 et 50 nm) déposés par la technique ALD sur les grandes zones de nanofils de silicium ordonné (SiNW), réalisée en combinant la lithographie à la nanosphère et la gravure chimique à base de métal, a été réalisée. Ces méthodes ont permis la morphologie et le contrôle organisationnel des SiNW sur une grande surface. L'étude détaillée des propriétés structurales et optiques de l'hétérostructure SiNWs / ZnO à noyau-coquille a été réalisée en utilisant respectivement la spectroscopie XRD, SEM, de réflectance et de photoluminescence. L'intégration des tableaux SiNWs en tant que noyau et ZnO comme coque peut avoir un impact important sur le développement d'éléments de détection avec des propriétés améliorées. Dans les recherches ultérieures, des films ZnO formés par ALD en tant que plate-forme de biocapteur optique pour la détection des protéines de type A du virus Grapevine (antigènes GVA) ont été représentés. La détection de l'antigène GVA a été effectuée en utilisant les changements dans le comportement de la bande PL liée à la GVA. La sélectivité du biocapteur a été prouvée. La possibilité de détecter les antigènes GVA sans étiquettes supplémentaires a été démontrée. Ainsi, on a développé un biosensor à base de photoluminescence à base de photoluminescence libre pour les antigènes GVA. Une autre partie de notre étude est un contrôle spécifique de l'ancrage des protéines par le développement d'une surface multifonctionnelle avec une grande gamme de sphères de polystyrène (PSS), produite par la lithographie de nanosphère et bloquant davantage l'adsorption non spécifique des protéines à la surface du PSS par SAM de PEG. La microscopie d'épifluorescence a été utilisée pour confirmer qu'après l'immersion de l'échantillon sur la protéine cible (avidine et anti-avidine), ces dernières sont spécifiquement situées sur une sphère de polystyrène. Ces résultats sont significatifs pour l'exploration de dispositifs basés sur un nanoarray à grande échelle de sphères de PS et peuvent être utilisés pour la détection de protéines cibles ou simplement pour structurer une surface avec des protéines spécifiques. Notre recherche comprend également l'ajustement des propriétés structurelles et l'amélioration des propriétés électroniques et optiques des nanolaminés 1D PAN ZnO / Al2O3 conçus par dépôt de couche atomique (ALD) et électrospinning. Les propriétés structurelles et optiques de Al2O3 / ZnO déterminées à partir des analyses XPS, TEM, FTIR, XRD et PL. L'amélioration des propriétés électroniques et optiques permettrait l'application dans différents domaines de tels capteurs et biosensorsThis thesis manuscript presents the investigations and potential applications as a (bio)sensor platform of the conform thin layers of ZnO and/or Al2O3/ZnO nanolaminates, deposited by atomic layer deposition (ALD) on the various substrates. First, a study of the optical properties of ZnO thin films (20 and 50 nm) deposited by ALD technique on the large areas of ordered silicon nanowires (SiNWs), produced by combining nanosphere lithography and metal-assisted chemical etching, was performed. These methods allowed the morphology and the organization control of SiNWs on a large area. The detailed study of structural and optical properties of core-shell SiNWs/ZnO heterostructure was done by utilizing XRD, SEM, reflectance and photoluminescence spectroscopy, respectively. Integration of SiNWs arrays as core and ZnO as shell can have a strong impact on the development of sensing elements with improved properties. In the further investigations, ZnO films formed by ALD as an optical biosensor platform for the detection of Grapevine virus A-type proteins (GVA-antigens) were represented. The GVA-antigen detection was performed using the changes in the GVA related PL band behavior. The biosensor selectivity has been proved. The possibility to detect GVA-antigens without additional labels has been demonstrated. Thus, label free and sensitive photoluminescence based biosensor for GVA-antigens has been developed. Another part of our study is a specific control of protein anchoring by the development of multifunctional surface with large-scale array of polystyrene spheres (PSS), which produced by nanosphere lithography and further blocking the unspecific adsorption of protein on the surface of the PSS by PEG SAMs. The epifluorescence microscopy was used to confirm that after immersion of sample on target protein (avidin and anti-avidin) solution, the latter are specifically located on polystyrene sphere. These results are meaningful for exploration of devices based on large-scale nanoarray of PS spheres and can be used for detection of target proteins or simply to pattern a surface with specific proteins. Our research also includes the tuning of structural properties and the enhancement of electronic and optical properties of 1D PAN ZnO/Al2O3 nanolaminates designed by atomic layer deposition (ALD) and electrospinning. The structural and optical properties of Al2O3/ ZnO determined from the XPS, TEM, FTIR, XRD and PL analysis. The enhancement of electronic and optical properties would allow application in different fields such sensors and biosensors
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Hwang, Dae Kun 1972. "Computational optical science of textured liquid crystals for biosensors, rheooptics, and carbon composites." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102509.
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Liquid crystals are functional materials used in displays, sensors, and biosensor applications, as well as structural materials used as precursors in the manufacturing of polymer superfibers and high performance carbon composites. While consumer display applications are based on defect-free homogeneous liquid crystals, the performance of biosensors devices and the characterization of structural material precursors is based on the presence of defects, textures, and heterogeneities. This thesis uses theory, modeling, and simulation to formulate the computational optical science of textured liquid crystals, and its applications in biosensors and material characterization methods.The computational optical science of textured liquid crystals is established by a comprehensive study of light propagation through cross-polars in thin liquid crystal films containing defects of significant complexity. Optical matrix methods widely used in display applications, including the aggregate model and the well-known Berreman method are quantitatively compared with the direct numerical simulation (DNS) of the Maxwell equations for anisotropic liquid crystal media.
Biosensors based on liquid crystal vision offer an affordable, fast, transportable means to detect viruses and proteins, through the disruption of the liquid crystal orientation upon protein surface adsorption. This thesis presents simulations of the texture formation process relevant to the LC biosensors based on the nematodynamic model and the matrix and DNS optical methods and identifies the optical factors that lead to optimal performance.
Rheooptics is an experimental tool used to better characterize the flow properties of liquid crystal polymer solutions. The rheooptics of Poly-gamma-Benzyl-L-Glutamate (PBLG) solutions under shear start-up flow between parallel plates was computed using the Berreman method and the FDTD method. The ubiquitous banded textures were reproduced using the Leslie-Ericksen equation for flowing liquid crystals. The optical signal of each band revealed the presence of characteristic double peak structures which correlated with the underlying defect texture of the flowing polymer solutions.
Carbonaceous mesophases are precursors materials used in the manufacturing of high performance carbon fiber composites. Reflection polarized optical microscopy (RPOM) is used to characterize the experimentally observed defects and heterogeneities in these materials.
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Sanogo, Yacouba. "Conception et fabrication de capteurs et de leur technique d’interrogation pour des applications dans les domaines de la santé et de l’environnement." Thesis, Cachan, Ecole normale supérieure, 2012. http://www.theses.fr/2012DENS0080/document.
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Le besoin croissant de biocapteurs optiques compacts, sélectifs, ultrasensibles, rapides et bas coût dans les domaines médical et environnemental a engendré une émergence de solutions technologiques, notamment les capteurs à bases de microrésonateurs optiques. Ces types de biocapteurs sont capables de fournir une détection sélective de très faibles concentrations de biomolécules si leurs surfaces sont fonctionnalisées. En revanche, les deux méthodes optiques d'interrogation actuelles, balayage spectral et variation de l’intensité, ne peuvent ni fournir la sensibilité de la phase du signal optique propagé dans le capteur, ni les paramètres opto-géométriques (perte par propagation, l'indice effectif, coefficient de couplage, etc) nécessaires pour une modélisation de la réponse du capteur. Pour accéder à ces informations, nous avons proposé d’utiliser l'interféromètre optique à faible cohérence sensible à la phase comme une technique alternative d’interrogation et de caractérisation de microrésonateurs. La première partie des travaux de cette thèse est consacrée à l’étude de conception et de réalisation de microrésonateurs monomodes possédant un facteur de qualité supérieur à 20000 dans l'eau. Cette étude a été validée par la réalisation technologique, à l'aide des procédés de photolithographie classique et de gravure sèche au plasma d'oxygène, de microrésonateurs polymères possédant des facteurs de qualité allant jusqu'à 38 200. La deuxième partie des travaux de thèse est dédiée à l'adaptation du dispositif PS-OLCI, initialement développé au Laboratoire National de Métrologie et d'Essais (LNE) pour interroger les composants des télécommunications optiques, pour la caractérisation de microrésonateurs optiques. Les résultats obtenus en évaluant les performances spatiales et spectrales de différents microrésonateurs ont montré que le dispositif PS-OLCI n'est pas seulement un outil d'interrogation et de caractérisation mais aussi un véritable outil d’aide à la conception de microrésonateurs optiques. Une modélisation, validée par l'ajustement des mesures expérimentales, de la réponse PS-OLCI d'un microrésonateur, met en évidence la relation existant entre l'interférogramme et les intégrales de Fresnel. La dernière partie de nos travaux concerne l'association du dispositif PS-OLCI et d’un composant optofluidique, constitué de microrésonateurs et d’un circuit microfluidique en polymères, pour la détection d’espèces biologiques. A cet effet, la molécule de glucose a été choisie pour démontrer la détection homogène ou volumique en solution aqueuse en obtenant respectivement les limites de détection de l'ordre de 50 µg/ml et de 2 µg/ml en exploitant l’intensité ou la phase des mesures PS-OLCI. Ces performances démontrent la capacité de notre capteur à déceler des biomolécules en faible concentration ainsi que la pertinence de la mesure de la phase, d'où l'intérêt du dispositif PS-OLCI. Pour remédier au problème de sélectivité du capteur en détection homogène, la méthode de détection surfacique est utilisée. La problématique de chimie de surface des polymères, c'est à dire la fonctionnalisation des surfaces des guides polymères en vue d’une détection surfacique, a d'abord été effectuée. Les limites de détection obtenues en détection surfacique sont ensuite évaluées à leur tour pour différents types de molécules particulièrement les protéines telles que la streptavidine ou la biotine. Les performances de détection de streptavidine obtenues sont au moins 10 fois meilleures que celles obtenues à l’aide de la technique de Résonance de Plasmons de Surface considérée à ce jour comme la technique de référence en biodétection sans marqueur. Ces premiers résultats, présentant des marges importantes d’amélioration, contribuent à démontrer que les capteurs à base de microrésonateurs optiques sont des candidats potentiels très prometteurs pour la détection de très faibles concentrations de biomolécules pour l’analyse biochimiqueThe increasing need for compact, selective, ultrasensitive, fast and affordable optical biosensors in the medical and environmental sectors gave rise to new technological solutions, especially regarding sensors based on optical microresonators. If their surfaces are functionalized, these biosensors can provide a selective detection of low concentrations of biomolecules. However, two common optical interrogation methods – spectral scanning and intensity variation – cannot provide the same sensitivity as the method using phase detection of the guided modes nor the opto-geometrical parameters (propagation loss, effective refractive index, coupling coefficient), needed for the modeling of the sensor response. To get this information, we proposed to use the Phase Sensitive-Optical Low Coherence Interferometer (PS-OLCI) as a new alternative technical solution for interrogation and characterization of microresonators. The first part of this thesis is dedicated to the conception and fabrication of single mode microresonators with a quality factor higher than 20 000 in water. This work was validated by the manufacture of polymer microresonators with a quality factor up to 38 200, using UV photolithography and Reactive Ion Etching (RIE) processes. The second part of this work covers the adaptation of PS-OLCI setup, initially developed at Laboratoire national de métrologie et d'essais (LNE), to interrogate optical telecommunication devices, for the characterization of optical microresonators. The results, obtained through the analysis of spatial and spectral performances of various microresonators, showed that the PS-OLCI setup is not only an interrogation and characterization tool but also a real support tool for designing optical microresonators. The performed modelling of the PS-OLCI and microresonator association response, validated by the fitting of the experimental data, demonstrated the relation between PS-OLCI measurements and Fresnel integrals. The last part of this work is dedicated to label free biosensing experiments using PS-OLCI setup associated to an optofluidic component, made of polymer optical microresonators and polymer microfluidic circuit, to detect biological species. The glucose molecule was chosen to demonstrate the homogeneous sensing experiments in aqueous solution. The obtained detection limits are around 50 µg/ml when we exploited intensity and around 2 µg/ml when we exploited the PS-OLCI measurements phase. These results demonstrate the high sensitivity of the proposed biosensor as well as the value of the optical phase measurement, hence the interest of PS-OLCI set up. To address the problem of sensor selectivity in homogeneous sensing method, surface sensing experiences were performed. The first step of this method was the functionalization of the sensor surface, by binding adequate recognition molecular sites to the sensor surface in order to immobilize target molecules. Proteins were then chosen to perform this very same type of experiences. The preliminary results in the 0.02 pg/mm2 range clearly show that our sensors is ten times more sensitive than Surface Plasmon Resonance, which is actually considered among the most successful label free sensing methods. These first results, which can be improved, demonstrate that the sensors based on optical microresonators are promising candidates for the detection of low concentrations of biomolecules for biochemical investigation
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Wu, Xiaojun. "Development of optical biosensors based on oxidases and hydrogels performing in organic phase and aqueous phase solvents." HKBU Institutional Repository, 2002. https://repository.hkbu.edu.hk/etd_ra/423.
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Gifford, Erika Lea. "Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28201.
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Biosensors have a multitude of important applications in basic research, environmental monitoring, biodefense, and medicine. This research aims to show that Ionic Self-Assembled Multilayers (ISAMs) adsorbed on Long Period Gratings (LPGs) can serve as a highly sensitive, robust, inexpensive optical-based biosensor platform. The ISAM technique is a layer-by-layer deposition method that builds nanometer-thick films based on the principle of Coulomb attraction between oppositely charged polyelectrolyte solutions while LPGs cause strong attenuation bands that enable an optical fiber to be extremely sensitive to changes in the surrounding environment. LPGs have been shown to be highly sensitive to the adsorption of nanoscale self-assembled films on the optical fiber cladding surface. In this work, we utilize Turnaround Point (TAP) LPGs, which possess even greater sensitivity than standard LPGs. This thesis focuses on evaluation of approaches to increasing the sensitivity of the sensor platfom, implementation of a biosensor for detection of several biomolecules, and preliminary evaluation of the potential for pH sensing.
For a thin-film coated TAP LPG, we have demonstrated that shifts in the transmitted light intensity at the resonant wavelength of the LPG can result from the variation in film thickness and/or refractive index. We have observed decreases in intensity as large a 7 dB for one bilayer of ISAM film (~1 nm), which corresponds to an 80% decrease in the transmitted light intensity at the resonant wavelength. We have also shown that the sensitivity of the TAP LPG sensor can be increased by implementing nm-thick ISAM films that have a refractive index greater than silica. Furthermore, it is shown that incorporation of silica nanoparticles into the ISAM films significantly increases sensitivity through increased surface area and thickness.
The biotin-streptavidin system was used as a model for implementaion and optimization of the ISAM-coated TAP LPG biosensor platform. Through evaluation of various biotin derivatives to maximize the amount functionalized onto the ISAM film, optimization of the ISAM film properties, and use of LPGs designed for higher sensitivity, the minimum detectable concentration of streptavidin was decreased from 0.0125 mg/ml to 12.0 ng/ml. The biosensor platform was then tested on prostate specific antigen (PSA), which is used as a clinical marker for early diagnosis of potential prostate cancer. Using a direct crosslinking approach of the monoclonal antibody to PSA into the ISAM film, a sensitivity level of 11.64 ng/ml PSA was obtained through combined optimization of the ISAM film and antibody surface coverage. Finally, the potential of ISAM TAP LPGs as pH sensors was examined based on the pH dependent swelling of ISAM films.Ph. D.
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Wang, Zhiyong. "Ionic Self-Assembled Multilayers Adsorbed on Long Period Fiber Gratings for Use as Biosensors." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29994.
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Biosensors have widespread applications in many areas. Currently the Surface Plasmon Resonance (SPR) biosensor is one of the most prevalent types of biosensor. However, it has several disadvantages such as being delicate, expensive, and non-portable. Ionic Self-Assembled Multilayers (ISAMs) adsorbed on Long Period Fiber Gratings (LPGs) provides an attractive platform for building optical sensors, which could potentially overcome the disadvantages of SPR biosensors. The ISAM technique is a type of layer-by-layer deposition technique for building nanoscale thin films. An LPG is a type of fiber device that is sensitive to physical property changes of the ambient environment. LPGs have been extensively investigated for use as optical sensors. We have carried out a study on combining these two techniques to build efficient biosensors.
In this thesis, we demonstrate ultra-sensitive LPGs whose attenuation can be changed by 25 dB (~99.7%) over a 48-nm spectral band, with ambient-index changes of only 2.7E-4. The device schematic allows arbitrarily high index sensitivities to be achieved, which makes it an attractive platform for realizing sensors and modulators that respond to small index changes. For a thin-film coated LPG, we find theoretically that the resonant wavelength shift of the LPG can result from either the variation of the thickness of the film and/or the variation of its refractive index. Furthermore, results illustrate that the sensitivity of the sensor could be enhanced using a nm-thick thin-film (e.g. ISAM films) whose refractive index is greater than silica. Experimentally, we demonstrate the fabrication of nm-thick ISAM films deposited on LPGs, which induces dramatic shifts in the resonant wavelength. The refractive index and the thickness of the ISAM film was precisely controlled by altering the relative fraction of the anionic and cationic materials combined with layer-by-layer deposition. Finally, we demonstrate that ISAM-coated LPGs can function effectively as biosensors by using the biotin-streptavidin system. These demonstrations confirm that the ISAM-LPG scheme provides a thermally-stable, reusable, and robust platform for building efficient optical sensors.Ph. D.
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Michael, Karri L. "Development of high-density optical fiber arrays : new designs and applications in microscopy, microfabrication and chemical sensing /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
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Thesis (Ph.D.)--Tufts University, 1999.Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Barreau, Stephanie. "Biosensing with sol-gel-immobilised proteins." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/27275.
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Low temperature-processed, porous sol-gel glasses represent a new class of materials for the immobilisation of biomolecules. If used to entrap biological recognition elements, these transparent and chemically inert glasses offer a new approach in the development of optical biosensors.
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Pierce, Mary E. "Engineering a fiber-optic implantable cardiovascular biosensor /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422954.
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