Дисертації з теми "Biosensor experiments"
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Popov, Piotr. "LIQUID CRYSTAL INTERFACES: EXPERIMENTS, SIMULATIONS AND BIOSENSORS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1434926908.
Повний текст джерелаPham, Errek Manh Trung. "Producing A Peptide For Use In A Blood Biosensor For Injury Detection." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1607519672342672.
Повний текст джерелаOcaña, Tejada Cristina. "Aptasensors based on electrochemical impedance spectroscopy." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/305103.
Повний текст джерелаIn the recent years, due to the need for rapid diagnosis and improvements in sensing, new recognition elements are employed in biosensors. One kind of these new recognition elements are aptamers. Aptamers are synthetic strands of DNA or RNA which are selected in vitro and have the ability to bind to proteins, ions, whole cells, drugs and low molecular weight ligands recognizing their target with high affinity and specificity. Several aptamer-based biosensors, also called aptasensors, have been recently developed. Among all the transduction techniques employed in biosensors, Electrochemical Impedance Spectroscopy has widely used as a tool for characterizing sensor platforms and for studying biosensing events at the surface of the electrodes. The important feature presented by this technique is that it does not require any labelled species for the transduction; thus, this detection technique can be used for designing label-free protocols thus avoiding more expensive and time-consuming assays. The main aim of this PhD work was the development of aptasensors using the electrochemical impedance technique previously mentioned for protein detection. For that, different types of electrodes were used, such as Graphite Epoxy Composite electrodes (GECs), Avidin Graphite Epoxy Composite electrodes (AvGECs) and commercial Multi-Walled carbon nanotubes screen printed electrodes (MWCNT-SPE). The work was divided in two main parts according to the detection of the two different proteins. The first part was focused on thrombin detection. First of all, different impedimetric label-free aptasensors based on several aptamer immobilization techniques such as wet physical adsorption, avidin-biotin affinity and covalent bond via electrochemical activation of the electrode surface and via electrochemical grafting were developed and evaluated. Then, AvGECs electrodes were compared as a platform for genosensing and aptasensing. With the aim to amplying the obtained impedimetric signal using AvGECs, an aptamer sandwich protocol for thrombin detection was used including streptavidin gold-nanoparticles (Strep-AuNPs) and silver enhancement treatment. The second part of the study was based on cytochrome c detection. Firstly, a simple label-free aptasensor for the detection of this protein using a wet physical adsorption immobilization technique was performed. Finally, with the goal to amplify the impedimetric signal, a hybrid aptamer-antibody sandwich assay using MWCNT-SPE for the detection of the target protein was carried out. In this way, the thesis explores and compares a wide scope of immobilization procedures, the use of label-free or nanocomponent modified biomolecules in different direct or amplified protocols, and the use of direct recognition and sandwich alternatives to enhance sensitivity and/or selectivity of the assay
Sena, Torralba Amadeo. "Development and application of innovative point-of-care biosensing platforms." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670851.
Повний текст джерелаEl objetivo de esta tesis ha sido el desarrollo y la aplicación de plataformas innovadoras de biosensado en el punto de atención. La tesis se divide en cinco capítulos seguidos de una sección de conclusiones generales. El Capítulo 1 comienza con una introducción general a los conceptos de biosensores y biosensado en el punto de atención. Luego, se enfoca en una de las pruebas de punto de atención más exitosas: el ensayo de flujo lateral (LFA). Los aspectos clave del ensayo, como los componentes y reactivos, los procedimientos de fabricación y operación están cubiertos en profundidad. El capítulo continúa con una revisión de los desafíos actuales de LFA ha enfrentado y las mejoras más relevantes reportadas en los últimos años. El Capítulo 2 describe brevemente los objetivos que motivaron este trabajo. El Capítulo 3 presenta una nueva plataforma de detección (PEB) que combina las características clave de un ensayo de flujo lateral, la prueba de punto de atención más utilizada, con las capacidades de tratamiento de muestras de la electroforesis. En particular, se demuestra la capacidad de PEB para separar diferentes tipos de partículas y detectar anticuerpos IgG humanos en muestras de sangre no tratadas. Finalmente, para hacer que la plataforma sea aplicable en el punto de atención, PEB se combina con un teléfono inteligente que controla la electroforesis y lee la señal óptica generada. El Capítulo 4 explica una estrategia simple y de bajo costo para mejorar el rendimiento analítico de los LFA. Mediante el uso de barreras de cera solubles, las nanopartículas se acumulan temporalmente en la parte superior de la línea de detección (TL). Este paso extendido de incubación interna promueve la formación del inmunocomplejo, generando una mejora de sensibilidad y de señal en comparación con la detección convencional de LFA para IgG humana (H-IgG). El Capítulo 5 presenta una plataforma de detección en el punto de atención que consiste en un microtubo y dos piezas de fibra de vidrio. El principio de detección se basa en la transferencia de energía de resonancia de Förster utilizando nanoclusters de oro como indicador de señal y nanopartículas de oro conjugadas con anticuerpos como un desactivador. La plataforma ha sido validada para la detección de Escherichia coli O157: H7 en agua de río y del grifo, demostrando una elevada sensibilidad.
The objective of this thesis has been the development and application of innovative biosensing platforms at the point of care. The thesis is divided into five chapters followed by a section of general conclusions. Chapter 1 begins with a general introduction to the concepts of biosensors and point-of-care biosensing. Then, it focuses on one of the most successful point-of-care tests: the lateral flow test (LFA). Key aspects of the assay, such as components and reagents, manufacturing and operating procedures are covered in depth. The chapter continues with a review of the current challenges LFA has faced and the most relevant improvements reported in recent years. Chapter 2 briefly describes the objectives that motivated this work. Chapter 3 introduces a new detection platform (PEB) that combines the key features of a lateral flow assay, the most widely used point-of-care test, with the capabilities of electrophoresis sample treatment. In particular, the ability of PEB to separate different types of particles and detect human IgG antibodies in untreated blood samples is demonstrated. Finally, to make the platform applicable at the point of care, PEB is combined with a smartphone that controls the electrophoresis and reads the generated optical signal. Chapter 4 explains a simple, low-cost strategy to improve the analytical performance of LFAs. By using soluble wax barriers, nanoparticles temporarily accumulate at the top of the detection line (TL). This extended internal incubation step promotes immunocomplex formation, generating improved sensitivity and signal compared to conventional LFA detection for human IgG (H-IgG). Chapter 5 presents a point-of-care detection platform consisting of a microtube and two pieces of fiberglass. The detection principle is based on Förster resonance energy transfer using gold nanoclusters as a signal indicator and antibody-conjugated gold nanoparticles as a quencher. The platform has been validated for the detection of Escherichia coli O157: H7 in river and tap water, demonstrating high sensitivity.
Carinelli, Soledad. "Biomarkers detection of global infectious diseases based on magnetic particles." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667765.
Повний текст джерелаInfectious diseases are becoming a major threat worldwide due to the fast dissemination and adaptation of pathogens favored by the unrestricted globalization. The primary role of diagnostics is to identify a disease. The rapid identification of a disease allows the patient to be placed on a specific antimicrobial therapy and avoid prolonged management on empiric, potentially inappropriate drug. Therefore, point-of-care (POC) devices that can reliably detect and/or monitor diseases would result in an improved care, and minimization of patient and societal cost of illness. Among them, electrochemical biosensors have the advantage of high sensitivity/specificity as well as simplicity of instrumentation, and can be easily expanded to multiplex detection platform. Furthermore, the integration of magnetic particles (MPs) in POC tests provides an even increased sensitivity and specificity due to the isolation and preconcentration of the target, whether MPs are modified with a specific recognition biomolecule. Modified-MPs can thus specifically bind the biomarkers and preconcentrate them from the complex specimen under magnetic actuation, preventing interferents before testing. Affordable emerging technologies requiring minimal training for final users, such as magnetic actuated electrochemical biosensors, are presented in this dissertation. Firstly, two simple diagnostic tests for CD4+ T lymphocytes quantification, directly in whole blood, and based on magnetic particles are presented. The assay is performed in an ELISA-like format for the optical detection or using graphite-epoxy electrodes for the electrochemical biosensing strategy. In both cases, the strategy has involved three main steps: a) immunomagnetic separation of CD4+ cells by antiCD3-MPs and labeling by using biotinylated antiCD4 antibody; b) enzymatic labeling; and c) detection based on the peroxidase activity. The dual labeling (CD3 and CD4 receptor) not only avoids interferences of other cells, but also increases the specificity of the assay. Thus, the development and evaluation of magnetic-actuated rapid HIV diagnostic platforms appropriate for their use in low resource settings for the following-up of patients under treatment is demonstrated. Secondly, an interferon- release assay based on electrochemical detection for interferon- transcript detection produced by isolated T lymphocytes is described. This approach also involves the integration of MPs for the isolation and preconcentration of three different targets (including whole T lymphocytes, mRNA transcripts and double-tagged DNA) in the same test. Accordingly, T lymphocytes are isolated from whole blood using antiCD3-MPs. Secondly, mRNA presenting poly(A) tail is preconcentrated on polydT-MPs from T lymphocyte. Afterward, mRNA is retrotranscripted and cDNA amplified by multiplex double-tagging PCR for the specific amplification of IFN- and GAPDH. Finally, one of the tags of the primers is used for the amplicons immobilization on streptavidin-MPs as support, while the electrochemical magneto-genosensing for transcript detection is performed using the other tag. This strategy results in an alternative for IFN- release assays, which can be used for identifying infectious states such as Tuberculosis. Finally, the design of a diagnostic test involving a rapid, specific and highly sensitive procedure based on isothermal amplification on MPs with electrochemical readout is presented. Isothermal amplification techniques are emerging as good candidates to replace PCR for the identification of infectious microorganism, since PCR-based method can be a critical barrier in low resource settings. An electrochemical DNA detection using padlock probes and the subsequent amplification with rolling circle and circle to circle amplification is presented in Chapter 6. This strategy has demonstrated to be a powerful combination for highly specific and sensitive nucleic acid detection that can be applied in clinical diagnosis. The electrochemical biosensors developed in this dissertation, offers considerable promise for obtaining information in a faster, simpler and cheaper manner compared to traditional methods for infectious disease diagnosis. Moreover, the strategies possess great potential in many applications, in low resource settings.
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.
Повний текст джерелаEsta 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
Otte, Ortiz Marinus Albertus. "Towards Highly Sensitive and Multiplexed Nanoplasmonic Biosensors." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/117188.
Повний текст джерелаIn this dissertation, different aspects of refractometric nanoplasmonic sensors are discussed. First, a theoretical and experimental sensing performance assessment is made of Localized Surface Plasmon Resonance (LSPR) sensors based on single gold nanorods, by directly comparing them to conventional thin film Surface Plasmon Polariton (SPP) sensors. Besides the discovery of a material-specific optimized spectral sensing region that can be accessed via precise nanoparticle engineering, this work reveals a better biosensing performance for LSPR sensors that can be further improved if certain - inherent - drawbacks are overcome. For this, arrays of gold nanodisks are used to identify and suppress such drawbacks. First, negative influences that stem from thin metal adhesion layers and the high refractive indices of the supporting substrate are analyzed. It is shown that the right choice of material and thickness for these adhesion layers, significantly improves the signal-to-noise ratio (S/N)-values of these biosensors. Besides, by placing the nanodisks on nanopillars, thereby distancing them from the substrate, much higher sensitivities can be obtained, providing a strategy that can be easily expanded to other plasmonic systems. Next, it is demonstrated that the employed arrays of gold nanodisks support a guided mode that besides other interesting nanophotonics applications, alters the far-field radiation of these nanoplasmonic structures in such a manner, that both enhanced sensitivities and improved S/N-ratios are obtained. Finally, combining all gathered knowledge, a road map is sketched towards the creation of a LSPR sensor with multiplexing capabilities and integrated microfluidics.
Alfonso, Pardo Wilmer. "Development of electrochemical platforms for DNA sensing." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/397662.
Повний текст джерелаEl presente trabajo de tesis está enmarcado en un proyecto de investigación y desarrollo (I+D) entre la empresa privada Genomica S.A.U., el Instituto de Bioingeniería de Cataluña (IBEC), la Universidad de Barcelona y la empresa alemana ChipShop Microfluidics. El objetivo principal es el desarrollo, puesta a punto y comercialización de un dispositivo electroquímico de diagnóstico médico para etapas tempranas de cáncer. El objetivo de la tesis es la creación, optimización y posterior integración de una interfaz de biosensado de ADN en el dispositivo de diagnóstico, siendo pieza fundamental en el desarrollo de éste. La interfaz escogida fue una monocapa autoensamblada (SAM) que hace las veces de biosensor y que es capaz de anclar secuencias de ADN como sondas de captura y así poder detectar, selectivamente, las secuencias objetivo complementarias. El dispositivo también cuenta con un sistema microfluídico y un sistema de amplificación de ADN de reacción en cadena de la polimerasa en miniatura. La SAM esta inmovilizada en un array electroquímico que consta de 64 electrodos de trabajo que funcionan como elemento transductor de la señal electroquímica redox de los eventos de hibridación que ocurren sobre ellos. La funcionalización y puesta a punto del dispositivo se llevó a cabo inmovilizando múltiples sondas de captura después de una optimización de las concentraciones entre las diferentes partes constituyentes de la monocapa. Técnicas ópticas y electroquímicas fueron utilizadas para la caracterización de cada etapa y técnicas de fotolitografiado y de impresión por pantalla fueron utilizadas para la fabricación de los componentes del dispositivo. Finalmente, y después de algunos cambios surgidos durante el desarrollo del dispositivo, se llega a un diseño final y a las pruebas con muestras reales, proceso que aún está en etapa experimental.
Bergua, Canudo José Francisco. "Nanobiosensors for contaminants detection in water." Doctoral thesis, TDX (Tesis Doctorals en Xarxa), 2020. http://hdl.handle.net/10803/670394.
Повний текст джерелаEsta tesis tiene como objetivo desarrollar biosensores para el monitoreo ambiental. Primero, se ha desarrollado un biosensor colorimétrico basado en lateral flow strips (LFS) para la detección y cuantificación de Escherichia coli como indicador fecal universal. En este caso, nanopartículas de oro (AuNP) se utilizan como transductores ópticos y anticuerpos policlonales como elementos de bioreconocimiento para capturar, marcar e indicar la presencia de la bacteria. Paralelamente, se ha desarrollado un sistema de filtración para mejorar la sensibilidad de las LFS. La optimización del flujo de la muestra a través de los diferentes materiales ha realizado mediante una técnica innovadora basada en el seguimiento del flujo de la bacteria bioluminiscente Aliivibrio fischeri, similar en tamaño y forma a E. coli. Finalmente, estos LFB se han probado con muestras de agua de ríos y aguas residuales, mostrando una sensibilidad similar y buena reproducibilidad y selectividad en todos los casos. En segundo lugar, se ha desarrollado un biosensor de toxicidad bioluminiscente para la detección y cuantificación de pesticidas en muestras de agua. En particular, Aliivibrio fischeri, una bacteria bioluminiscente, se ha utilizado como elemento de bioreconocimiento y transductor porque aumenta y disminuye la bioluminiscencia de acuerdo con la concentración de compuestos tóxicos en las muestras de agua. Además, el óxido de grafeno (GO) se ha utilizado como un potenciador del crecimiento no específico para promover el crecimiento bacteriano y aumentar la sensibilidad del sistema al detectar parcialmente la bioluminiscencia emitida por A. fischeri. La detección y cuantificación de la bioluminiscencia se realizó con un teléfono móvil que permite una evaluación de la toxicidad del agua de forma portátil, más barata, y más fácil de usar que los estándares en los laboratorios. En tercer lugar, se ha desarrollado una plataforma portátil basada en un teléfono móvil para realizar ensayos que requieren una detección óptica, incluyendo ensayos colorimétricos, fluorescentes y bioluminiscentes. Esta plataforma se ha utilizado para llevar a cabo y analizar pruebas ELISA estándar basadas en resultados colorimétricos para la detección de la inmunoglobulina humana y una proteína del coronavirus. Además, el sistema permite realizar un seguimiento de la agregación de AuNPs en función del color de la solución. Por otro lado, la plataforma se ha utilizado para detectar y cuantificar quantum dots (QD) y otros indicadores fluorescentes (por ejemplo, fluoresceína), así como para realizar pruebas ELISA fluorescentes basadas en estos transductores. Además, la plataforma permite realizar lecturas bioluminiscentes con aplicaciones como el análisis de la toxicidad del agua. Finalmente, la plataforma es útil para el cultivo de bacterias, mediciones de turbidez y detección de resistencia a antibióticos.
This thesis aims to develop biosensing tools for environmental monitoring. First, a colorimetric lateral flow biosensor (LFB) has been developed for the detection and quantification of Escherichia coli as a universal fecal indicator. Gold nanoparticles (AuNPs) are used as optical transducers and polyclonal antibodies as the biorecognition elements to capture, tag and indicate the presence of the bacteria. In parallel, a filtration system has been developed to improve the sensitivity of the LFBs. The optimization of the flow properties of the different lateral flow materials has been done by an innovative technique based on the tracking of the flow of the bioluminescent bacteria Aliivibrio fischeri, similar in size and shape to E. coli. Eventually, these LFBs have been tested with river and sewage waters, showing similar sensitivity and good reproducibility and selectivity in all the cases. Second, a bioluminescent toxicity biosensor has been developed for the detection and quantification of pesticides in water samples. In particular, Aliivibrio fischeri, a bioluminescent bacteria, has been used as the biorecognition element and the transducer because it turns up and down bioluminescence according to the concentration of toxic compounds within the water samples. Besides, graphene-oxide (GO) has been used as a non-specific growth enhancer to promote bacterial growth and increase the sensitivity of the system by partially screening the bioluminescence emitted by A. fischeri. The detection and quantification of the bioluminescence has been performed by a smartphone that allows for a cheaper, more user friendly, and portable water toxicity assessment. Third, a smartphone-based portable platform has been developed for the performance of optical sensing, including colorimetric, fluorescent, and bioluminescent assays. This platform has been used to perform and read standard ELISA tests based on colorimetric outputs for human IgG and coronavirus detection. In addition, the system allows for tracking AuNPs aggregation based on the color output of the solution. On the other hand, the platform has been used to detect and quantify quantum dots (QDs) and other fluorescent reporters (i.e. fluorescein), as well as performing fluorescent ELISA tests based on these transducers. Next, the platform allows for bioluminescent readouts with applications in toxicity analysis. Eventually, the platform is suitable for bacteria culture, turbidity measurements, and drug screening for antibiotic resistances assessment.
Diéguez, Moure Lorena. "Optical grating coupler biosensor and biomedical applications." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/101149.
Повний текст джерелаEsta tesis consiste en el diseño, fabricación y test de un Biosensor Óptico basado en redes de difracción y sus aplicaciones en biomedicina. Los biosensores ópticos son dispositivos que detectan interacciones biomoleculares específicas mediante un transductor óptico. Exhiben alta sensibilidad, alta estabilidad mecánica, son inmunes a las interferencias electromagnéticas y permiten medidas no destructivas. En los Biosensores Ópticos por Onda Evanescente un modo guiado se propaga a lo largo de la guía de ondas mientras que la onda evanescente interactúa con la superficie del sensor, reconociendo cualquier interacción biomolecular que provoque una modificación en el índice de refracción efectivo de la guía óptica. En este caso, la inserción de luz láser en la guía óptica se produce con ayuda de una red de difracción grabada en la superficie del sensor. Para un ángulo muy preciso se excita un modo guiado. Como consecuencia de las reacciones en la superficie se produce un cambio en el ángulo de acoplo. La medida en tiempo real del ángulo de acoplo, en función de la actividad bioquímica en la superficie es la base de este tipo de biosensor óptico. El objetivo es fabricar sensores de bajo coste en polímero y también en distintos materiales que permitan calibrar otras técnicas. Otro objetivo de esta tesis es la calibración de los sensores y de las distintas soluciones buffer comúnmente usadas en biosensado. Como aplicación, se ha usado un equipo comercial (Optical Waveguide Lightomode Spectroscopy, OWLS, MicroVacuum) para estudiar, mediante control electroquímico, el crecimiento y la liberación de multicapas de PLL/DNA para aplicaciones en administración de fármacos. También se ha usado el OWLS para optimizar la inmovilización de receptores olfativos en un dispositivo biosensor para el desarrollo de una nariz bioelectrónica.
Sánchez, Huertas César. "Nanophotonic biosensors for deciphering cell regulation pathways." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/368562.
Повний текст джерелаThis Doctoral Thesis focuses on the development of innovative biosensor devices as alternative analytical techniques for the evaluation of different gene regulating pathways in order to obtain a more informative and accurate diagnosis and follow-up therapy of cancer. We propose the use of a novel nanophotonic biosensor for a rapid, highly sensitive and direct analysis of these regulating routes without the need of labeling or amplification steps. Different genetic and epigenetic disorders associated with cancer appearance and progression are studied taking advantage of circulating nucleic acids as target biomarkers. For the label-free detection and evaluation of these biomarkers, we have employed two different optical biosensors: (i) the well-known Surface Plasmon Resonance (SPR) biosensor, and (ii) a novel nanotechnology-based interferometric device, the Bimodal Waveguide (BiMW) biosensor. First, an in-depth study of different biofunctionalization strategies on both platforms is presented. Several surface chemistry procedures have been optimized for an efficient immobilization of nucleic acids as biorecognition elements that ensure a highly sensitive target detection with maximum selectivity and reproducibility, especially for the direct analysis of complex human samples such as urine or serum. The optimized strategies were applied for the evaluation of specific and clinically relevant gene regulation pathways, such as RNA alternative splicing events, micro-RNA regulation, or DNA methylation processes. All the developed methodologies have been assessed in terms of selectivity, sensitivity and reproducibility, and in some cases, they have been validated with real samples. The obtained results overcome some of the critical drawbacks of the current methodologies employed for the analysis of such processes and offer standardized protocols for a highly sensitive and selective detection with minimal sample manipulation. The work in this Thesis has opened a new Research line in our Group and combines our wide knowledge in the development of powerful photonic biosensor technology with our bioanalytical expertise in order to offer advanced analytical tools for the direct and effective evaluation of gene regulating pathways as new solutions for cancer diagnosis and follow-up therapy
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.
Повний текст джерелаThis 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.
Ramirez, Priego Patricia. "Low-cost point-of-care biosensor device for clinical diagnosis in developing countries." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/671902.
Повний текст джерелаActualmente el diagnóstico de Tuberculosis (TB) se realiza en laboratorios centralizados, empleando equipos voluminosos, reactivos complejos y personal capacitado, aumentando los costes y el tiempo para obtener los resultados. Por esta razón, el objetivo de esta Tesis Doctoral es el desarrollo de una plataforma point-of-care (POC) capaz de ofrecer una respuesta rápida y fiable en el diagnóstico de TB. Para llevar a cabo este objetivo, la plataforma POC integra un novedoso sensor fotónico incorporado en un cartucho de micofluídica desechable. El sensor fotónico consiste en un conjunto de interferómetros Mach-Zehnder que ofrecen una alta sensibilidad. En primer lugar, se llevó a cabo una caracterización óptica para estudiar el rendimiento de la plataforma POC y su capacidad para ser empleada en aplicaciones biosensoras. Una vez caracterizada ópticamente, se evaluaron distintas estrategias de biofuncionalización para incorporar anticuerpos específicos como bioreceptores a la superficie del sensor. Después de un estudio en profundidad, se seleccionó y empleó la estrategia de biofuncionalización óptima para el análisis de los biomarcadores de TB. Los biomarcadores de TB se evaluaron tanto en solución tampón como en muestras biológicas, particularmente en orina humana. El biomarcador más prometedor y conocido de TB es el lipoarabinomanano (LAM), un componente de la pared celular bacteriana. En concreto, la detección de este biomarcador fue validada con muestras clínicas de pacientes con TB y donantes sanos, mostrando la capacidad de nuestra plataforma POC para discriminar a aquellos pacientes con Tuberculosis activa. Además, el diseño del sensor fotónico permite la detección simultánea de seis biomarcadores distintos. Teniendo esto en cuenta, hemos llevado a cabo una prueba de concepto del empleo de la plataforma biosensora POC para la detección de un panel de biomarcadores de TB utilizando nanolitografía Dip-Pen para la deposición de cada bioreceptor en cada sensor. Nuestros resultados, validados en estudios clínicos más amplios, podrían tener importantes implicaciones diagnósticas. Además, nuestro biosensor POC ofrece una serie de ventajas en comparación con los métodos recomendados por la Organización Mundial de la Salud.
Nowadays, Tuberculosis (TB) diagnosis is carried out at centralised laboratories, employing bulky equipment, complex reagents, and trained staff, increasing costs and the time to obtain the results. For that reason, the aim of this Doctoral Thesis is to develop a point-of-care (POC) platform able to deliver a prompt and reliable response to TB diagnosis, taking advantage of a highly sensitive evanescent wave optical sensor. The POC platform integrates a novel photonic sensor consisting of a Mach-Zehnder Interferometer transducer array incorporated in a disposable microfluidic cartridge. Firstly, an optical characterisation was carried out to study the new POC performance and its ability to be employed for biosensing applications. Once the POC platform was optically characterised, diverse biofunctionalisation strategies were tested in order to incorporate specific antibodies as bioreceptors to the sensor surface. After an in-depth study, the optimal biofunctionalisation strategy was selected and employed for the analysis of the TB biomarkers. The TB biomarkers were evaluated in both buffer and biological samples, particularly human urine. The most promising and well-known TB biomarker was lipoarabinomannan (LAM), a bacterial cell wall component. In particular, this biomarker detection was validated with clinical samples from TB patients and healthy donors, showing the ability of our POC platform to discriminate those patients with active TB. Moreover, taking advantage of the photonic sensor design, which allows the simultaneous detection of six different biomarkers, we initiated the proof-of-concept of the POC platform for a TB biomarker panel detection using Dip-Pen Nanolithography for each corresponding bioreceptor deposition. Our results, if validated with larger clinical studies, could have important diagnostic implications taking into account the advantages added by our POC biosensor in comparison with the methods recommended by the World Health Organisation.
Universitat Autònoma de Barcelona. Programa de Doctorat en Biotecnologia
Ricci, Simona. "Liquid-gated transistors for biosensing applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670786.
Повний текст джерелаEn esta tesis, hemos estudiado diferentes aspectos relacionados con los transistores orgánicos activados por líquido, en particular los transistores de efecto de campo orgánicos activados por electrolitos (EGOFET) y los transistores electroquímicos orgánicos (OECT). Los dispositivos EGOFET se fabricaron depositando a partir de soluciones pequeñas moléculas de semiconductores orgánicos (OSC) mezclados con polímeros aislantes, a través de la técnica de Bar-assisted meniscus shearing (BAMS). BAMS es una técnica rápida, de bajo costo y escalable que permite la formación de películas finas cristalinas y uniformes. Los EGOFET se estudiaron para el desarrollo de un biosensor para la detección de un biomarcador de enfermedades neurodegenerativas, incluidas las enfermedades de Parkinson, es decir, la alpha-sinucleína. Además, se emplearon dispositivos OECT para la biodetección de α-sinucleína, para estudiar el posible uso de estos dispositivos como inmunosensores, campo que aún está menos explorado en la literatura. Finalmente, se fabricó un EGOFET totalmente flexible basado en una pequeña molécula semiconductora mezclada con un polímero aislante y se evaluó su respuesta eléctrica bajo tensión mecánica, por primera vez, hasta donde sabemos, para dispositivos EGOFET.
In this thesis, we have studied different aspects related to liquid-gated organic transistors, in particular electrolyte-gated organic field-effect transistors (EGOFETs) and organic electrochemical transistors (OECTs). EGOFET devices were fabricated by depositing from solution small molecules organic semiconductors (OSC) blended with insulating polymers, through the bar-assisted meniscus-shearing technique (BAMS). BAMS is a rapid, low-cost and scalable technique that allows the formation of crystalline and uniform thin films. The EGOFETs were studied for the development of a biosensor for the detection of a biomarker for neurodegenerative diseases, including Parkinson’s diseases, namely α-synuclein. Further, OECT devices were employed for the biosensing of α-synuclein, to give an insight into the possible use of these devices as immunosensors, field which is still less explored in literature. Finally, an all-flexible EGOFET based on a small molecule OSC blended with an insulating polymer thin film, was fabricated and its electrical response under bending strain was evaluated, for the first time, as far as we know, for liquid-gated OFETs.
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.
Повний текст джерелаDante, 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.
Повний текст джерелаDuring 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.
Pacios, Pujadó Mercè. "Carbon nanotubes as platforms for biosensors with electrochemical and electronic transduction." Doctoral thesis, Universitat Autònoma de Barcelona, 2011. http://hdl.handle.net/10803/84001.
Повний текст джерелаThe convergence of nano and biotechnology is enabling scientific and technical knowledge for improving human well being. Within this new field of nanobiotechnology, the area of (bio)sensors is the most developed and the one which has the highest potential for short-term applications. In this context, (bio) sensors based on electrochemical principles stand out due to their marked advantages in terms of simplicity, robustness, low cost, miniaturization capability and integration to devices. These sensors are becoming very attractive for rapid and simple diagnostic, in fields such as biotechnology, clinical and environmental research. Historically, carbon has been a widely used and practical electrode material due to its desirable properties for electrochemical applications. Available in a variety of structures, carbon electrodes provide, in general, good electrical conductivity, high thermal and mechanical stability, a wide operable potential window with slow oxidation kinetics and, in many cases, electrocatalytical activity. On top of that, they are recognized as versatile and easy handling materials, and also praised by their rich surface chemistry which has been exploited to influence surface reactivity. Thus, different forms of carbon have played for a long time an important role in solid electrode development. More recently, the appearance of carbon nanotubes (CNTs) has intensified some of these properties and propelled in an unprecedented way their electrochemical and electroanalytical applications. The nanometre size and high aspect ratio of the carbon nanotubes are the distinct features which have contributed more to innovative electrochemical applications and to establish the differences with respect to other carbon materials. Accordingly, the principal aim of this work has been to exploit the properties of carbon nanotubes to design novel nanodevices. The prominent electrochemical properties of carbon nanotubes have impelled the design of diverse electrode configurations. That, combined with their chemical properties and (bio)functionalization versatility have made these materials very appropriate for the development of electrochemical biosensors. The first part of the study has been focused on the use of carbon nanotubes as electrochemical transducers and the relation between their structure and their electrochemical reactivity. It was found that the edges of carbon nanotubes play an important role in the electrochemical response, which was then used for the design and development of new carbon nanotubes-based electrode platforms. In the second part of the study, we have taken advantage of the capability of CNTs for being tailored in different geometrical arrangements, from their biocompatibility, their chemical robustness and their interesting covalent/non-covalent chemical functionalization possibilities, to develop biosensor platforms. Specifically, the (bio)sensor behaviour of different carbon configurations functionalized with redox proteins (catalase and myoglobin) has been evaluated. Such proteins exhibit high sensitivity to oxygen and peroxide and are capable to catalyze the reduction of such species, which hold promise as oxygen and peroxide sensors. Then, following the same approach, we have used CNT microelectrode arrays covalently functionalized with specific DNA probes or with aptamers. The detection of hybridization events or the specific interaction between aptamers and proteins were sensitively monitored by different electrochemical techniques (cyclic voltammetry, chronocoulometry or impedance spectroscopy) in presence of redox markers. The third and last part of the study is focused on exploiting the semiconductor character of carbon nanotubes for sensor technology by using a field effect transistor configuration (FET). The CNT-FET device has been optimized for operating in liquid environment by performing passivation protocols. This, together with the use of bifunctional pyrene linkers for the immobilization of the aptamers, has allowed sensitive electronic detection of protein/aptamer interaction. Additionally, we were also able to follow up protein adsorption and protein conformational changes on the CNT walls under liquid gating. The results of this thesis work show that these electrochemical and electronic CNT devices can become highly promising for biomolecule sensing and for the monitoring of biological processes.
Aller, Pellitero Miguel. "Design and development of a self-powered electrochromic biosensor." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667346.
Повний текст джерелаCurrent trends in analytical chemistry aim at developing simpler and more affordable sensing devices. Electrochromic materials enable the fabrication of electrochemical sensors that exploit colour changes as a means to reduce instrumentation requirements. Although many chemical compounds used in electroanalysis exhibit electrochromic properties, the inclusion of these materials in the construction of electrochromic analytical sensors has begun to emerge only recently. This thesis focuses on the development of a new type of analytical devices relying on the use of electrochromic materials, reducing to a minimum the required components, and removing the need for silicon-based electronics. First, the working principle of self-powered electrochromic sensors is presented, demonstrating how with the appropriate geometry it is possible to obtain a sensing platform capable of providing a quantitative readout of the analyte concentration. The experimental data obtained are combined with the use of numerical simulations to develop a mathematical model that helps to have a further understanding of the behaviour of the device. Moreover, these simulations were used as a design tool to improve the performance of future electrochromic devices. New materials in the form of screen-printing pastes have also been formulated to substitute certain components of the device such as the electrochromic material or the electrolyte. These materials were used in the last part of the thesis to manufacture a fully printed electrochromic sensor able to provide quantitative results without the aid of an external signaling device.
Soler, Aznar Maria. "Nanoplasmonic biosensors for clinical diagnosis at the point of care." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/298172.
Повний текст джерелаThis Doctoral Thesis focuses on the development of novel analytical methodologies in optical biosensors as alternative solutions for diagnosis or therapy monitoring of relevant diseases, such as allergy, celiac disease or cancer. In particular, we propose the use of nanoplasmonic biosensors for a rapid, sensitive and label-free detection of biomarkers present in human fluids. Both the well-known Surface Plasmon Resonance (SPR) biosensor and an innovative nanoplasmonic biosensor based on gold nanodisks surfaces have been evaluated for their real application in the clinical field. The different biosensor methodologies make use of antibodies, either as biorecognition elements in immunoassays or as specific disease biomarkers for diagnostics. First, an in-depth study of two site-directed antibody immobilization strategies is presented for the direct immunoassay of protein biomarkers in biological fluids. In second place, a novel immunosensing strategy is proposed for the detection of gluten-derivative peptides in urine as a rapid and non-invasive technique for dietary control in celiac patients. On the other hand, two assays have been developed employing the nanoplasmonic biosensor to detect blood circulating antibodies as disease biomarkers. First, we have designed an alternative approach for drug allergy diagnosis (in particular for amoxicillin) based on dendrimer-based receptors, which enable the detection IgE antibodies directly in serum. And second, a new biosensing strategy is assessed to quantify specific tumor-related autoantibodies for the early diagnosis of colorectal cancer. The work in this Thesis combines the wide knowledge of the research group in the design and fabrication of powerful biosensor technology with the development of surface activation chemistry and bioanalytical techniques to overcome current challenges related to costly and time-consuming clinical analysis. Besides, the strong experience of our research group in technological transfer and the established collaborations during this doctoral work with companies as Biomedal S.L. or Protein Alternatives S.L. open up interesting opportunities to facilitate the technology-transfer process for the real implementation of Point-of-Care biosensors.
Nagar, Bhawna. "Printed Graphene for energy storage and sensing applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667240.
Повний текст джерелаThe focus of this thesis has been the design and preparation of flexible graphene-based electrodesand their printing using different techniques for applications in energy storage, specifically supercapacitors and electrochemical sensing devices. Different strategies have been employed keeping in mind the end application and accordingly graphene or its hybrids wereprepared using different synthetic routes along with careful selection of the available printing techniques as well as the substrates. For energy storage part(Chapter 2), Supercapacitor devices with high capacitances, energy and power density have been demonstrated over Cloth (Carbon), Paper (Common A4 paper) and Plastic substrates using different printing techniques, graphene hybrids as well as hybrid electrolytes. In the case of Sensing applications(Chapter 3),two sensors have been demonstrated over plastic substrates. A high sensitivity DNA (Bio)sensor for viruses using one step facile printing is shown, which structure and operation principle can be extended to other bio-analytes with interest for applications in various areas. In another study, extremely high concentration yet stable graphene inkjet printable ink has been prepared and its use as a bacterial sensor has been demonstrated as a proof of concept. The graphene ink prepared could produce highly conducting patterns that in principle can offer other bio or chemical sensing with high sensitivities. Studies of different printing techniques were carried out and suitable inks were formulated and tested for each technique with optimization of the printing parameters in order to obtain reproducible films and hence reproducible device fabrication has been the focus. The main printing/coating techniques used in this Thesis are Doctor blade coating, Inkjet printing, screen printing and wax stamping technique. The project therefore involved a very important part of synthesis and characterization of graphene and derivatives, formulation of inks and finally device integration and testing
Maldonado, Vázquez Jesús Manuel. "Interferometric biosensors for rapid identification of nosocomial infections." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/403761.
Повний текст джерелаThis doctoral Thesis is focusing on the development of a novel optical biosensor as an alternative technique for the identification of nosocomial infections in a faster way. This new tool will also facilitate the finding of the most effective treatment for each patient, reduce the nonspecific use of broad-spectrum antimicrobial drugs, and facilitate new antibiotic treatments. We propose the use of a novel nanophotonic sensor based on an interferometric transducer device, the Bimodal Waveguide device (BiMW) for the rapid, specific, highly sensitive and direct analysis of different pathogens associated to nosocomial infections and their multidrug resistant. First, we assessed and optimized different biofunctionalization strategies for an efficient immobilization of the required biorecognition receptors, which ensure a highly sensitive bacterial detection with enough selectivity and reproducibility, particularly suitable for the direct detection in complex matrices, such as urine and ascitic fluid. The optimized strategies were employed for the identification of various nosocomial pathogens such as Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa using antibodies as biorecognition elements. The detection of Escherichia coli was done in human ascitic fluid. Finally, the BiMW biosensor was employed to identify the multidrug-resistant bacteria such as: i) the identification of methicillin-resistant Staphylococcus aureus (MRSA) using a specific aptamer, which is able to discriminate among a susceptible one to antibiotic and a multidrug-resistant Staphylococcus, and (ii) the ultra-sensitive detection of multidrug-resistant E. coli genes without PCR amplification. This Thesis takes advantage of the knowledge in photonics biosensors and bioanalytical methods in our Group in order to develop a powerful tool for the direct and effective identification of nosocomial pathogens and their antibiotic-resistance in a rapid and label-free scheme.
De, la Rica Quesada Roberto. "New concepts for electrical detection of biomolecules." Doctoral thesis, Universitat Autònoma de Barcelona, 2007. http://hdl.handle.net/10803/3584.
Повний текст джерелаEn primer lloc, es presenta un nou tipus de transductor impedimetric (I). Es va escollir un disseny basat en dos electrodes interdigitats per dos motius principals. Primer, aquesta geometria permet monitoritzar tant la resistència como la constant dieléctrica d'una solució, la qual cosa fa dels electrodes interdigitats eines més versatils que altres tipus transductors. Segon, els electrodes presenten una curta penetració del camp electric, la qual cosa els fa mes sensibles als canvis que tenen lloc a prop de la seva superfície. Aquest fet permet monitoritzar canvis locals en les magnituds d'interés. Finalment, són apropiats no nomes per construir sensors sinó també actuadors. Aquesta geometria sembla ser útil en experiments de dielectroforesi. Una innovació introduïda en aquesta tesi es el material escollit per fabricar els electrodes: silici policristal-lí o polisilici. El polisilici pot ser facilment modificat per donar lloc a superficies amb particulars propietats químiques i físiques, fent d'aquest material un excel-lent candidat per a la manufactura de biosensors, comparable a altres aproximacions com la quemisorció de alcanotiols sobre electrodes d'or.
Els esmentats electrodes interdigitats es van fer servir per probar dos nous sistemes de transducció. Ambdues aproximacions comparteixen un tret comu: aprofiten la capacitat dels electrodes interdigitats per mesurar canvis local en les propietats elèctriques del medi on es troben submergits. En II, aquest fet és utilitzat per monitoritzar una reacció enzimàtica, i es mostra com la característica de mesura local en electrodes interdigitats dóna lloc a una detecció més sensible. A més, es demostra que aquesta aproximació es adequada per la detecció de proteïnes fent servir l'enzim com a marca en un immunoassaig. En III, els electrodes interdigitats actuen com a sensor i actuador. Com a actuador, els electrodes son capaços de concentrar esferes de làtex a la seva superficie. Com a transductors, la presencia de les micropartícules aïllants a la seva superficie dóna lloc a un canvi en la geometria de la cel-la, que pot ser detectat monitoritzant tant la resistència com la capacitat de la solucio. Aquest mode de funcionament es paral-lel al dels sensors magnetoresistius, i el principi de transduccio proposat es presenta com a una alternativa a ells.
Finalment, un quart treball es presenta en aquesta tesi (anex). Comparteix dues característiques en comú amb els treballs previs: el sustrat (silici) i una metodologia per la inmoblització de biomolecules (silanització). Les seves aplicacions son, però, diferents i cobreixen un rang més ampli d'aplicacions. En concret, una nova metodologia pel nanoestructurat de superfícies, de baix cost i fàcil disponibilitat és presentada. Es van aconseguir motius fets amb molècules de silà amb dimensions inferiors als 10 nm. En el marc de la biodetecció, aquesta nova tècnica per nanoestructurat superficial es propossa com a alternativa a la nanolitografia dip-pen per la manufactura de nanomatrius de biomolècules. Les petites dimensions dels motius obtinguts obren el cami per la consecució de nanomatrius d'una única molècula.
This work discusses different aspects related to the design of biosensors and biodetection systems. It describes the fabrication and characterization of particular electric transducers together with the development of new transduction systems and the finding of new methodologies for biomolecule nanoarray fabrication.
Firstly, a new type of impedimetric transducer is presented (I). A two-electrode interdigitated design was chosen, mainly for three reasons. First, this geometry allows the monitoring of both the resistivity and the dielectric constant of a solution, thus making interdigitated electrodes more versatile tools than other kind of transducers. Second, they present short electric field penetration depths, which make them more sensitive to changes occurring close to their surface. This fact enables the monitoring of local changes in the magnitudes of interest. Finally, they are suitable for constructing not only sensors but also actuators. This geometry appears to be useful in dielectrophoresis experiments. One innovation introduced in this thesis is the material chosen to fabricate the electrodes: polycrystalline silicon, also known as polysilicon. Polysilicon can be easily modified to render surfaces with distinct physical and chemical properties, thus making this material an excellent approach for biosensors manufacture, comparable to other approaches like alkanethiol chemisorption on gold electrodes.
The aforementioned interdigitated electrodes were used to test two new transduction principles. The two approaches share a common feature: they rely on the ability of interdigitated electrodes to measure local changes in the electrical properties of the medium where they are immersed. In II, this is used to monitor an enzymatic reaction, and it is shown that the characteristics of measuring local changes at interdigitated electrodes result in a more sensitive detection. Furthermore, the feasibility of this approach for protein detection is demonstrated by using the enzyme as a label for performing an immunoassay. In III, the interdigitated electrodes act both as a transducer and as an actuator. As an actuator, the electrodes are able to concentrate latex beads at their surface. As a transducer, the presence of the insulating microparticles at their surface results in a change in the geometry of the cell, that can be detected by monitoring either the resitance or the capacitance of the solution. Such device performance is parallel to that of magnetoresistive biosensors, and the proposed transduction principle is envisaged as a suitable alternative to them.
Finally, a fourth work is presented in this thesis (Annex). It shares two features in common with the previous works: the substrate (silicon) and a method for biomolecule immobilization (silanization). However, the applications are somehow different, and cover a wider range. Precisely, a new methodology for low cost, easily available nanopatterning is shown. Features made of silane molecules, with dimensions less than 10 nm are successfully patterned. In the frame of biodetection, this new nanopatterning technique is proposed as an alternative to dip-pen nanolithography in nanoarray manufacture. Moreover, the small dimensions of the obtained patterns pave the way for the achievement of single-molecule nanoarrays.
Parra, Cabrera César Alejandro. "Microfluidic devices with integrated biosensors for biomedical applications." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284758.
Повний текст джерелаEn años recientes, la comunidad de LOC ha enfocado todos sus esfuerzos en la investigación de nuevas aplicaciones para la biomedicina y biotecnología. Algunos países en vías de desarrollados no tienen tecnologías de diagnóstico adecuadas, además el suministro y almacenamiento de los reactivos es en muchos casos limitado, y en ocasiones cuentan con un acceso limitado al consumo de energía. Por otra parte, los países desarrollados se han encontrado con una población envejecida, y por lo tanto se ha generado la necesidad de contar con nuevas tecnologías para el diagnóstico de enfermedades las cuales sean accesibles y orientadas a una terapia más personalizada. Tanto la microfluídica como los LOC han permitido la integración de funciones de análisis complejas capaces de desarrollar herramientas de diagnostico más precisas, de bajo coste y confiables. Actualmente toda la atención se ha centrado en el diseño de aplicaciones para administración de fármacos 1, análisis celular 2 y diagnostico de enfermedades 3. La introducción de la microfluídica ha servido para mejorar el desarrollo de nuevos dispositivos point-of-care, pero todavía existen algunos problemas que han evitado la producción masiva de estos LOC. Las áreas en las que se pretende conseguir una mejora son la recolección de la muestra, mejora de la interfaz entre el chip y el usuario, tratamiento previo de la muestra, mejorar la estabilidad de los reactivos, trabajo con muestras complejas, detección múltiple de biomarcadores y simplificación del sistema de medida 4. Nuestros esfuerzos se han dedicado en desarrollar un sistema LOC con capacidad de detección electroquímica ajustable a cualquier biomarcador, dependiendo únicamente en la cantidad de muestra y los tiempos de análisis. Nuestros dispositivos microfluídicos cuentan con biosensores integrados de bajo coste con capacidad de auto-funcionalización. La funcionalización de los biosensores se realiza in-situ y selectivamente, antes de la detección, manteniendo el área de detección inerte hasta el inicio de la prueba. Los reactivos y el área de detección se almacenan por separado y entran en contacto hasta el inicio del experimento, lo cual facilita el método de fabricación. Se ha podido desarrollar este trabajo gracias a los estudios previos realizados en nuestro grupo en distintas disciplinas, tales como: microfluídica 5-8, funcionalización de superficies 9-14 y biosensores electroquímicos 15-19. Bibliografía 1. I. U. Khan, C. A. Serra, N. Anton and T. Vandamme, Journal of Controlled Release, 2013, 172, 1065-1074. 2. H. Andersson and A. Van den Berg, Sensors and Actuators B: Chemical, 2003, 92, 315-325. 3. M. J. Cima, Annual Review of Chemical and Biomolecular Engineering, 2011, 2, 355-378. 4. C. D. Chin, V. Linder and S. K. Sia, Lab on a Chip, 2012, 12, 2118-2134. 5. R. Rodriguez-Trujillo, C. A. Mills, J. Samitier and G. Gomila, Microfluidics and Nanofluidics, 2007, 3, 171-176. 6. R. Rodriguez-Trujillo, O. Castillo-Fernandez, M. Garrido, M. Arundell, A. Valencia and G. Gomila, Biosensors and Bioelectronics, 2008, 24, 290-296. 7. O. Castillo-Fernandez, R. Rodriguez-Trujillo, G. Gomila and J. Samitier, Microfluidics and Nanofluidics, 2014, 16, 91-99. 8. J. Comelles, V. Hortigüela, J. Samitier and E. Martínez, Langmuir, 2012, 28, 13688-13697. 9. E. Prats-Alfonso, F. García-Martín, N. Bayo, L. J. Cruz, M. Pla-Roca, J. Samitier, A. Errachid and F. Albericio, Tetrahedron, 2006, 62, 6876-6881. 10. J. Vidic, M. Pla-Roca, J. Grosclaude, M.-A. Persuy, R. Monnerie, D. Caballero, A. Errachid, Y. Hou, N. Jaffrezic-Renault, R. Salesse, E. Pajot-Augy and J. Samitier, Analytical Chemistry, 2007, 79, 3280-3290. 11. Y. Hou, S. Helali, A. Zhang, N. Jaffrezic-Renault, C. Martelet, J. Minic, T. Gorojankina, M.-A. Persuy, E. Pajot-Augy, R. Salesse, F. Bessueille, J. Samitier, A. Errachid, V. Akimov, L. Reggiani, C. Pennetta and E. Alfinito, Biosensors and Bioelectronics, 2006, 21, 1393-1402. 12. S. Rodríguez Seguí, M. Pla, J. Minic, E. Pajot‐Augy, R. Salesse, Y. Hou, N. Jaffrezic‐Renault, C. A. Mills, J. Samitier and A. Errachid, Analytical Letters, 2006, 39, 1735-1745. 13. A. Lagunas, J. Comelles, E. Martínez and J. Samitier, Langmuir, 2010, 26, 14154-14161. 14. A. Lagunas, J. Comelles, S. Oberhansl, V. Hortigüela, E. Martínez and J. Samitier, Nanomedicine: Nanotechnology, Biology and Medicine, 2013, 9, 694-701. 15. M. Castellarnau, N. Zine, J. Bausells, C. Madrid, A. Juárez, J. Samitier and A. Errachid, Materials Science and Engineering: C, 2008, 28, 680-685. 16. M. Castellarnau, N. Zine, J. Bausells, C. Madrid, A. Juárez, J. Samitier and A. Errachid, Sensors and Actuators B: Chemical, 2007, 120, 615-620. 17. M. Kuphal, C. A. Mills, H. Korri-Youssoufi and J. Samitier, Sensors and Actuators B: Chemical, 2012, 161, 279-284. 18. D. Caballero, E. Martinez, J. Bausells, A. Errachid and J. Samitier, Analytica Chimica Acta, 2012, 720, 43-48. 19. M. Barreiros dos Santos, J. P. Agusil, B. Prieto-Simón, C. Sporer, V. Teixeira and J. Samitier, Biosensors and Bioelectronics, 2013, 45, 174-180.
Castañeda, Briones María Teresa. "Electrochemical stripping analysis and nanoparticles for affinity biosensors." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3277.
Повний текст джерелаComparando el Bi(NO3)3-GECE con el electrodo de película de mercurio comúnmente usado y electrodo de película de bismuto desarrollado antes por nuestro grupo, el nuevo electrodo propuesto ofrece un notable funcionamiento en el análisis de metales pesados en cantidades traza, que puede ser de gran ventaja en electroquímica, contribuyendo a una aplicabilidad más amplia de técnicas electroquímicas por redisolución relacionadas con electrodos "sin mercurio". Además de aplicaciones ambientales el electrodo desarrollado basado en bismuto tendría interés especial para la aplicación en la detección de puntos cuánticos (QDs) basados en metales pesados. Tales aplicaciones están actualmente en proceso de estudio en nuestro grupo de investigación para la detección de ADN.
Las otras partes de la tesis se dedican al desarrollo de nuevos sensores de ADN y proteínas basados en la misma técnica electroquímica de redisolución y el uso de nanopartículas de oro como marcas.
Actualmente la detección electroquímica de secuencias de ADN específicas vía el evento de hibridación es una cuestión importante por lo cual diversas estrategias han sido propuestas.
Genosensores electroquímicos de afinidad basados en el marcaje con nanopartículas de oro (AuNPs) y el uso de partículas paramagnéticas (MB) como plataforma para la inmovilización de la sonda de ADN de captura también han sido desarrollados en esta tesis a fin de demostrar la inducción magnética eficaz de un nuevo electrodo de grafito-epoxi composite-magnético (M-GECE) el cual fue construido también con pasta de grafito-epoxi composite con un pequeño imán de neodimio integrado.Todos los ensayos para la detección electroquímica de la hibridación del ADN desarrollados en esta tesis fueron basados en la detección directa de las marcas de AuNPs por medio de la técnica de voltametría de pulso diferencial (DPV) usando el M-GECE donde la intensidad de la corriente de la señal generada es directamente proporcional a la cantidad de ADN en la muestra. Como también ha sido demostrado, con el sensor de ADN asistido magnéticamente, el ADN analito condujo a una muy bien definida señal mientras que esencialmente ninguna señal fue observada para el ADN no complementario.
Un nuevo inmunoensayo electroquímico sensible ha sido desarrollado, también basado en AuNPs como marca y MB como plataforma. El método fue evaluado para un inmunoensayo heterogéneo no competitivo de una IgG humana como proteína modelo. La detección electroquímica fue llevada a cabo en la misma forma que lo fue para ADN.
La detección electroquímica de marcas de AuNPs en biosensores de afinidad usando métodos de redisolución permite el estudio detallado de la hibridación de ADN así como también inmuno-reacciones con interés en aplicaciones relacionadas con genosensores o inmunosensores. Los métodos electroquímicos usados para la detección de AuNPs como marca pueden ser muy prometedores tomando en cuenta su sensibilidad alta, límite de detección bajo, selectividad, simplicidad, bajo coste, y disponibilidad de instrumentos portátiles.
Como conclusión final, las estrategias de análisis electroquímico de ADN y proteínas fueron demostradas con éxito y debido a los resultados prometedores su uso en muestras reales es viable. Tales biosensores de ADN e inmunosensores dan lugar a un enorme potencial de aplicación principalmente para diagnóstico clínico y monitoreo ambiental entre otros campos.
In the first part of this thesis a new graphite-epoxy composite electrode containing bismuth nitrate [Bi(NO3)3-GECE)], as built-in bismuth precursor as a possible alternative for electrochemical stripping analysis of trace heavy metals has been developed. Individual and simultaneous measurements of Pb and Cd were carried out and the results clearly showed the advantages of the Bi(NO3)3-GECE in combination with square wave anodic stripping voltammetry (SWASV) technique for heavy metals detection. Fast and effective analyses of trace metal ions such as Pb and Cd among others in environmental samples of soil, natural waters and effluents can be carried out by using the new Bi(NO3)3-GECE constructed. The inherent advantage of no necessity of mercury removes many of the objections for the use of the developed sensor.
When comparing the Bi(NO3)3-GECE with the commonly used mercury film electrode and previously developed bismuth film electrode, the newly proposed electrode offers a remarkable performance in analysis of trace heavy metals, which can be advantageous in electrochemical, hence contributing to the wider applicability of electrochemical stripping techniques in connection with "mercury-free" electrodes. Beside environmental applications the developed bismuth based electrode would have special interest for application to heavy metal based quantum dots. Such applications are currently in the studying process at our research group for DNA detection.
The other parts of the thesis are dedicated to the application of electrochemical stripping analysis in connection to gold nanoparticles for DNA and protein detection.
Currently the electrochemical detection of specific DNA sequences via hybridization event is an important issue by which diverse strategies have been proposed. Affinity electrochemical genosensors based on labelling with gold nanoparticles (AuNPs) and the use of paramagnetic beads (MB) as platform for the immobilization of capture DNA probe have been also developed in this thesis in order to demonstrate the effective magnetic triggering of a new magnetic-graphite epoxy composite electrode (M-GECE) which was constructed with graphite-epoxy composite paste, with a small neodymium magnet integrated.
All the assays for the DNA hybridization electrochemical detection developed in this thesis were based on the direct detection of AuNPs labels (anchored onto the M-GECE) by means of differential pulse voltammetry (DPV). The intensity of the generated current is directly proportional to the amount of DNA at the sample. As also has been demonstrated, with this magnetically assisted DNA sensor, target DNA leaded to very well defined signal whereas essentially no signal was observed for non-complementary DNA.
By the other side a novel, sensitive electrochemical immunoassay has been also developed based in AuNPs as label and MB as platform. The method was studied and evaluated for a noncompetitive heterogeneous immunoassay of a human IgG as a model protein. The electrochemical detection was carried out in the same way that as for DNA.
The electrochemical detection of AuNPs labels in affinity biosensors using stripping methods allows the detailed study of DNA hybridization as well as immunoreactions with interest in genosensor or immunosensor applications. The developed detection methodologies may be very promising taking into account their high sensitivity, low detection limit, selectivity, simplicity, low cost, and availability of portable instruments.
As final conclusion, the DNA and protein electrochemical analysis strategies were successfully demonstrated and according to the promising results obtained its use for real samples is viable. Such DNA biosensors and immunosensors hold an enormous application potential principally for clinical diagnostic and environmental monitoring among other fields.
Ferraz, Colomina Rosa María. "Development of allosteric biosensors for the diagnosis of infectious diseases." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3922.
Повний текст джерелаEn este estudio, el biosensor proteico NF795gpC, útil para la detección de anticuerpos anti-virus de la inmunodeficiencia humana (VIH), ha sido caracterizado. La proteína NF795gpC es una beta-galactosidasa modificada previamente sintetizada en nuestro laboratorio, que contiene el péptido antigénico P1 de la proteína gp41 de VIH insertado entre los residuos 795 y 796. La inserción de péptidos en lugares permisivos expuestos del enzima, permite la síntesis de proteínas que responden a la presencia de anticuerpos específicos. El hecho de que contengan inserciones, hace que estas proteínas tengan una actividad enzimática reducida. Sin embargo, en presencia de anticuerpos específicos para el péptido insertado, estos enzimas híbridos traducen la interacción antígeno-anticuerpo en un incremento de actividad enzimática fácil de medir. Finalmente, y teniendo un ejemplo previo con el virus de la fiebre aftosa, este principio puede extenderse a la detección de otras enfermedades infecciosas que producen una respuesta immune mediada por anticuerpos.
Primero se optimizó el ensayo buscando las concentraciones óptimas de proteína y sustrato y también analizando el efecto sobre sensibilidad, ratio señal-fondo y rango de respuesta, de seis sustratos diferentes. La proteína NF795gpC fue también inmovilizada en un soporte para analizar su capacidad de respuesta en estas condiciones, siendo el primer paso para un futuro desarrollo de un sistema de detección útil para hacer medidas de campo.
El análisis de los diferentes tipos de anticuerpos específicos presentes en muestras de suero con el sensor mostró una correlación entre la cantidad de inmunoglobulinas IgG4 y la respuesta, considerándose esta inmunoglobulina como la mayormente responsable de la activación del sensor.
Finalmente, nuevos enzimas alostéricos fueron sintetizados para mejorar la sensibilidad del sistema previamente descrito. El hecho de que la proteína NF795gpC contiene solamente un único inserto representa una limitación a la hora de diagnosticar la enfermedad, llegando solo a un 94% de coincidencia entre este y el método estándar normalmente utilizado para diagnosticar VIH. Por tanto, la inserción de otros fragmentos antigénicos del virus en la proteína permitiría aumentar el número de anticuerpos VIH específicos y, por tanto, también aumentar la sensibilidad del sistema. El desarrollo de un sistema mucho más completo representaría un gran avance en la salud pública y también sería de gran importancia para entender mejor el mecanismo de regulación enzimática en biosensores alostéricos.
Biosensors have become important tools in the detection of different types of molecules of analytical interest. Among them, protein-only biosensors stand out due to their ease production and use, what allow a cheaper development and applicability with low costs, especially important in low resource areas. A better and quicker diagnosis of illnesses would allow a faster treatment and an effective use of the available resources.
In this study, the protein-only biosensor NF795gpC, suitable for the detection of anti-human immunodeficiency virus (HIV) antibodies, has been characterized. NF795gpC protein is an engineered beta-galactosidase previously developed in our laboratory, containing the antigenic P1 peptide of gp41 protein of HIV in between the residues 795 and 796. The insertion of small peptides in permissive solvent exposed sites of the enzyme produces hybrid beta-galactosidases with a reduced enzymatic activity but allows the protein to respond enzymatically to peptide-specific antibodies. In presence of anti peptide monoclonal antibodies or polyclonal sera, these hybrid enzymes translate the antigen-antibody interaction into an easily measurable increase of the enzymatic activity. Furthermore, and having a previous example with FMDV, this principle can be extended to other infectious diseases producing an antibody response.
First, the sensing assay was optimized looking for the optimal concentrations of NF795gpC protein and substrate generating a higher sensing response, and also analyzing the sensor response regarding sensitivity, signal-background ratio and range of response with six different substrates. Protein NF795gpC was also immobilized into a support to analyze the sensor response in these conditions, being the first step to the further development of a sensor device useful for field measurements.
The analysis of the different types of antibodies present in sera samples through the sensor showed a correlation between the amount of IgG4 subpopulation of antibodies of a group of sera samples and the sensing signal, considering this immunoglobulin as the most important for sensor activation.
Finally, new allosteric enzymes were constructed in order to improve the sensitivity of the test. The fact that the NF795gpC contains only one type of HIV peptide represents a limitation to the proper diagnosis of HIV infection, arriving only to a 94% of agreement between this test and the standard method normally used for HIV detection. Hence, the insertion of other antigenic fragments of HIV into the beta-galactosidase could allow the detection of other specific antibodies. The development of a more complete device could represent big advances in public health and also be helpful in a better understanding of the mechanism of enzymatic regulation in allosteric biosensors.
Pino, Flavio. "Development of nanomaterials for environmental monitoring." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/325142.
Повний текст джерелаEnvironmental monitoring based on biosensing systems has increased its relevance not only in the research field but also in the real industrial application. This is due to the advantages of such analytical platforms especially their simplicity and their cost/efficiency. Moreover, the recent advances in nanoscience and nanotechnology increase the emerging of new nanomaterials which have interesting electrical properties such as their capacity to improve the electrode conductivity. This has a particular interest in the development of electrochemical biosensing systems. The combination of nanomaterials with electrochemical biosensing platforms can build up powerful analytical tools for the environmental monitoring. This represents the main objective of this PhD Thesis, that divided in six chapters describes the development and application of three new biosensing platforms for environmental monitoring using nanomaterials. The first chapter of the thesis gives a general introduction on environmental monitoring of pollutants and offers a brief description and classification of these compounds. This chapter also gives an overview of the relevance of the use of nanomaterials in biosensing systems for environmental monitoring with a detailed review of the last published works describing also their innovation aspects and also the possible drawbacks. In Chapter 3 the biosensing platform for environmental monitoring based on the inhibition of acetylcholinesterase is described. The developed system uses magnetic beads and acetylcholinesterase enzyme over Boron Doped Diamond Electrode. Moreover, through the use of magnetic beads and the surface characteristics of the electrode, this platform is used as multi use system with high reproducibility able also to measure the pesticide chlorpyrifos in real sample (Yokoama river, Japan). In Chapter 4 a simultaneous detection system of pollutants for catechol (a phenol derivative) and chlorpyrifos (an organophosphate pesticide), is developed. Such sensing is achieved through a SPCE modified with IrOx NPs and tyrosinase. The proposed biosensor reports improvement in the sensitivity for catechol compared to previously reported biosensors. This biosensor shows also a high sensitivity for chlorpyrifos while being used in a tyrosinase inhibition mode operation. Finally the efficiency of this biosensor is explored for real applications in river and tap water showing great possibilities for future application as a low cost platform. In Chapter 5 a free enzymatic bio-sensing system based on CuO nanoparticles for detection of phenols compounds and for a high toxic herbicide (Diuron) is proposed. Such sensing is achieved through a SPCE where CuO NPs create a stable complex with phenolic compounds that are measured through electrochemical reaction at electrode surface. Moreover it is one of the first applications using CuO NPs for environmental monitoring. CuO NPs have the function to mimic the active centre of tyrosinase obtaining results comparable with other enzymatic platforms. This analytical platform can be used for real sample applications due to the fact that the detection limit is within the requested levels of monitoring established by the legislation. Annex A shows a very interesting review over the biosensing systems inenvironmental monitoring using nanomaterials. This review was published in a very high impact factor journal (Chemical Review Impact factor of 46.658).
Zaffino, Rosa Letizia. "Development of a nano sensor for direct-electric free-label detection of DNA’s hybridization and single nucleotide polymorphism." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/384708.
Повний текст джерелаLa detección de hibridación de cadenas de ADN es un reto relevante científicamente y tecnológicamente, que puede aprovechar de las posibilidades proporcionadas por los alcances en los procesos de nano fabricación y caracterización, inspiradores de la idea de una medicina en el punto de atención. El propósito de este trabajo es de establecer un sistema de detección de hibridación de ADN, y polimorfismo de un solo nucleótido (SNP), basado en la medida eléctrica de la reasistencia de un nano-gap funcional izado con el ADN diana. El desarrollo y test del sistema se ha llevado a cabo fijando diferentes objetivos. Un estudio preliminar de la literatura relacionada con las propiedades eléctricas del ADN se ha conducido con la finalidad de establecer el marco de factibilidad del proyecto. De acuerdo con los resultados de este estudio ha sido posible idear el sistema y optimizar su eficacia respeto a las experiencias reportadas. Fijar una estrategia de fabricación de los dispositivos capaz de proveer nano-gaps aptos a la medida de conductividad muy baja, según una rutina de fácil implementación y con alta reproducibilidad de los resultados. Estos se han caracterizados mediante el utilizo de diferentes técnicas basadas primariamente en métodos de detección Óptica y Eléctrica/Electro-química. Obtener la bio-funcionalización selectiva de los electrodos en el nano-gap testando y caracterizando métodos diferentes. Probar el principio de funcionamiento del sistema a través de la medida de la conductividad en los nano-gap durante las diferentes etapas de funcionalización con los bio-receptores y el DNA target. Optimizar el sensor testando su selectividad respeto a la presencia de mutaciones, la sensibilidad a medir diferentes concentraciones del target, y finalmente la posibilidad de regeneración del dispositivo después desnaturalización del ADN hibridado
Corso, Christopher David. "Theoretical and experimental development of a ZnO-based laterally excited thickness shear mode acoustic wave immunosensor for cancer biomarker detection." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24728.
Повний текст джерелаCommittee Chair: William D Hunt; Committee Member: Bruno Frazier; Committee Member: Dale Edmondson; Committee Member: Marie Csete; Committee Member: Peter Edmonson; Committee Member: Ruth O'Regan
López, Muñoz Gerardo Arturo. "Simple and low cost nanostructured plasmonic biosensor for sensitive and multiplexed biodetection." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/665242.
Повний текст джерелаThe increasing demand for analytical platforms that are reliable and, at the same time, easy to use and compact, that require low sample consumption and provide high sensitivity and real-time response, have provided considerable innovation in the design of the biosensors. Among all of them, those based on surface plasmon resonance phenomena (SPR) have been the subject of great scientific interest in recent decades because they provide high sensitivity and simplicity in the detection schemes. With the advance in nanofabrication techniques, the development of optical sensors based on plasmonic nanostructures has represented an excellent way to integrate them into Lab-on-a-chip devices with a small size, with the ability to solve some of the current challenges related to the analysis times, the volume of sample required and the feasibility of detecting several analytes at the same time multiplexed. With the purpose of offering simple and inexpensive biosensing tools, this Doctoral Thesis presents the development of nanoplasmonic biosensors integrated in Lab-on-a-Chip (LOC) platforms for the multiplexed biosensing of different analytes in real time. The developed sensor is based on the use of commercial Blu-Ray discs as a substrate containing nano-slits to generate the plasmon resonance phenomena by coating them with different metallic layers on a nanometric scale. The developed nanobiosensors are a very promising alternative that could replace conventional analysis techniques, simplifying processes and overcoming the main current challenges related to sensitivity, cost and time required for clinical diagnosis.
Fabri, Faja Nuria. "Clinical diagnosis and pathogen detection with a novel multiplexed nanophotonic point-of-care biosensor." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667899.
Повний текст джерелаThis Doctoral Thesis focuses on a novel point-of-care device based on a nanophotonic microarray biosensor for the direct and label-free quantification of multiple clinical biomarkers for clinical diagnosis and pathogen detection directly on patient’s sample. The recently developed biosensor is a new large-field-of-view interferometric microscope which measures phase shifts upon changes in refractive indexes. Firstly, the optical physics behind the novel device and its feasibility to be used for biomolecules detection and quantification have been evaluated. Then, several analytical assays based on the use antibodies as bioreceptors have been developed and their performance evaluated. Finally, with the aim of using it as a specific biosensor, the immunoassay that showed the best performance has been applied to actual biomarker detection. Specifically, the biomarkers selected are related with the diagnosis of sepsis, a clinical condition characterized for a grave whole-body inflammatory response caused by an infection. There is an urgent need for fast diagnosis of sepsis because this condition is currently the main cause of death in Intensive Care Units and its incidence is increasing worldwide with a mortality rate between 40 to 50% in developed countries. The work in this Thesis combines the wide knowledge of the research group in the design and creation of biofunctionalised surfaces and the implementation of bioanalytical techniques to achieve cheap, fast and robust biosensors that overcome current challenges related to costly and time-consuming clinical analysis.
Sebastián, Ávila José Luis. "Desarrollo de aptasensores para la detección de bacterias enteropatógenas." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/460682.
Повний текст джерелаThe overall objective of this Thesis was to develop different biosensors based on aptamers to detect enteropathogen bacteria. This objective was accomplished through the study of different detection strategies which were proposed based on the unique properties of aptamers such as the capacity to present different conformational structures after linking to the target molecule, stability and ease of chemical functionalization. The affinity of the aptamer against the Salmonella typhimurium was confirmed by Microcontact Printing (μCP), Atomic Force Microscopy (AFM) and Fluorescence Microscopy. Then, a magnetic particle detection system was developed as a capture, pre-concentration and detection platform based on an indirect competitive test. Colorimetric and electrochemical detection, using differential pulse voltammetry (DPV) were performed. In both detection alternatives, cross-reactivity of Salmonella typhimurium with Escherichia coli O157 Shiga and Shigella sonnei was observed, with no cross- reactivity with Proteus mirabilis, Bacillus cereus, Kocuria lutea and Escherichia coli k5. In the next phase of the thesis, two electrochemical biosensors were developed, one based on the direct detection of the binding to the bacterium by electrochemical impedance spectroscopy (EIS) and the other based on the enzymatic inhibition caused by the conformational change of the aptamer after binding with the bacterium. In the second case the DPV technique was used to measure the activity of alkaline phosphatase. The best results were obtained with the impedance biosensor because as it showed improved behavior parameters (lower LOD, higher sensitivity and shorter analysis time). In addition, the construction of the aptasensor is simple as it consists of a single step. Selectivity tests carried out on all detection strategies showed that the developed detection systems were able to discriminate the bacterial group classified as enteropathogens (Salmonella typhimurium, Escherichia coli O157 Shiga and Shigella sonnei) from other bacteria (Escherichia coli K5, Proteus mirabilis, Bacillus cereus and Kocuria lutea). Hence, the affinity of the aptamer for Salmonella typhimurium is not specific for this bacterium and there is also an equivalent affinity for E. coli O157 Shiga and Shigella sonnei.
Wang, Daniel. "Bioconjugation Techniques and Experimental Processing of Myeloperoxidase Detection System." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1586272161296483.
Повний текст джерелаCadevall, Riera Miquel. "Bismuth based (nano)materials and platforms for (bio)sensing." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285769.
Повний текст джерелаThe thesis is focused on the fabrication of new sensing and biosensing platforms for pollutants detection. Although bismuth-based micro and nanomaterials seem to be the appropriated materials to achieve this objective nevertheless new platforms including for example those based on paper are also proposed. In the first chapter the main objectives of this thesis are described in detail. The introduction part (chapter 2) of this thesis is dedicated to the revision of the recent reports / achievements on bismuth-based nanomaterials in different application fields that include medicine, photodegradation of organic pollutants, cosmetics, pigments and alloys. An important section of this part is focused on the description of the effect of bismuth-based materials in heavy metals and biosensing applications. Bismuth nanoparticles are found as an innovative material in heavy metals sensing and biosensing applications. A study on the effect of the modification of screen-printed electrodes with bismuth nanoparticles and its use for the heavy metal detection is shown (chapter 3). Different modifications of polyol based bismuth nanoparticles synthesis have been evaluated in aim to obtain the more efficient nanoparticles with interest in heavy metal sensing. In addition the results obtained for the detection of lead and cadmium is also shown in the same chapter. In the chapter 4 a new electrode modification strategy is presented. This new strategy is based on the use of magnetic core/shell bismuth nanoparticles. Taking advantages of the bismuth oxide presence onto the shell of these nanoparticles, heavy metal detection in different On-Off sensing platforms is shown. The modification of electrodes is clearly demonstrated by doing cycles with both modification and cleaning of the electrodes obtaining a kind of digital (On-Off) response of heavy metals. To solve sampling and sample pretreatment issues a heavy metal sensing platform that uses a paper-based lateral flow chip is also developed and described at chapter 5. Fabrication and the optimization of this new heavy metal sensor are shown; it takes advantage of the use of a filter paper substrate. This new platform is capable to detect lead and cadmium in different matrixes including mud. In the last chapter (chapter 6), the integration of bismuth nanoparticles into a phenol biosensing system is shown. It takes advantages of the use of tyrosinase enzyme which brings certain selectivity in phenolic compounds detection. Morphological and electrochemical characterizations of the developed biosensor also are shown in this chapter. The developed biosensor shows good performance in catechol detection. Finally in the chapter 7 the general conclusions and some future perspectives are given.
Cipri, Andrea. "Carbon nanotubes and metal nanoparticles as electrode platform for sensors and biosensors." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/377462.
Повний текст джерелаThis work is mainly focused on the improvement of the properties of sensors and/or biosensors using carbon nanotubes and metal nanoparticles as electrode platform. After having gone through a good amount of literature examples, to reach this goal it has been decided to embed the metal nanoparticles on the carbon nanotubes surface to be able to take advantage of both material properties; for this reason, various synthetic procedures from the literature has been tested, modifying and optimizing them. This first step of the work was aimed to find a facile and quick synthetic protocol to generate a nano-hybrid material and it ended with an effective one-pot synthetic protocol that allows having the final desired material without intermediate purification steps. Of course the protocol has to be slightly modified depending on the desired metal nanoparticles. The obtained nano-hybrid materials have been characterised, especially through transmission electron microscopy (TEM) but also some time with scanning electron microscopy (SEM), after every synthesis to verify if the protocol was working. The next step has been a test of the nano-hybrid material, applying it to the surface of an epoxy graphite electrode (largely used in our lab) or a screen-printed electrode (SPE) for the detection of a biomolecule, Tyrosine. This test showed remarkable results (Article 1) with a clear improvement of the detection ability and sensitivity of the nano-hybrid material against the bare screen-printed electrode or the modification with only carbon nanotubes (without metal nanoparticles). After this success few different nano-hybrid materials have been prepared with different metal nanoparticles with the objective to try them in an electrode array system commonly used in our lab, the electronic tongue system, used for the resolution of mixtures of analytes. An electronic tongue system is not just an array of sensors (this would be better explained in the Introduction of this work), but it also needs a step of data processing since the analytes involved in the process supply very similar results; for this, an advanced chemometric treatment is needed, (in our case using Artificial Neural Networks). With the aim of gathering new variants, in this case the use of enzymatic biosensors, part of this work has been carried out at the Lund University (Sweden) in collaboration with the group of Prof. Lo Gorton; in this way, the computer processing part could be applied without having to worry also of the electrode optimization, since in that group they already had optimized biosensors that could be used for our purpose. This collaboration resulted in an interesting outcome (Article 3 – manuscript) where we have been able to build as a proof-ofconcept a novel bio-electronic tongue with variation of a specific enzyme (cellobiose dehydrogenase – CDH), a sensing element never used before in this manner. The last step of this work has been the integration of the synthesised nano-hybrid materials in the sensors for the electronic tongue used in our lab. The targets of the electronic tongue have been the sugars present in sugarcane bagasse used for the production of bio-fuels. The results collected and the goodness of prediction of the electronic tongue system have been satisfactory and they have been recently published (Article 2), showing a proof-of-concept of a working system for sugar mixtures resolution.
González, Guerrero Ana Belén. "Bimodal waveguide interferometer device based on silicon photonics technology for label-free and high sensitive biosensing." Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/107886.
Повний текст джерелаOptical biosensor devices based on evanescent wave detection could overcome the limitations of conventional diagnostic tests (expensive and time-consuming) due to the possibility of carrying out the detection in real-time and using a label-free scheme. Among the different optical transducers, interferometric devices have evidenced the best limit of detection (LOD) for refractive index changes of bulk solutions (10-7-10-8 Refractive Index Units, RIU) and for surface sensing (in the pg/ml range) and a wider linear range. However, usual interferometric transducers (Mach-Zehnder or Young interferometers) employ the Y-junction to split or recombine light, a drawback for the coherence and performance of the device due to standard tolerances of microfabrication techniques. To overcome these problems, we have developed a simple configuration based on a single straight waveguide where two modes of the light of the same polarization are interfering between them. This simple approach avoids the complexity of the usual interferometric transducers and as a consequence, more reliable and reproducible biosensors can be obtained. This thesis is focused on the development and characterization of a new photonic transducer, the Bimodal Waveguide device (BiMW), for label- free and high sensitive biosensing. To achieve this, the following steps have been pursued: 1. Design, fabrication, and optical characterization of an optical transducer operating by two-mode interference principle. 2. Development and optimization of biofunctionalization strategies on the transducer surface using silanization techniques. 3. Study of the applicability of the biosensor with the demonstration of bioanalytical diagnosis of relevant problems. The transducers are fabricated at wafer level in Clean Room facilities, which warrants a cost-effective and mass-production of the sensor chips. The device is highly sensitive to small changes in the refractive index occurring on the sensor area, leading to a detection limit of 2.5×10-7 RIU for bulk changes in refractive index solutions. The biofunctionalization of the sensor area is one of the most crucial aspects of this work. Optimized functionalization procedures have been achieved, which has been employed to immobilize different types of bioreceptors (DNA strands, proteins, and antibodies) on the surface. The optimized protocols have been used for the demonstration of different bioapplications such as the detection of hormones, bacteria, or complementary DNA sequences. The results presented in this work have highlighted the superior performance of this device in comparison with conventional diagnostics tests due to: i) the possibility of monitoring biomolecular interactions in real-time and by using a label-free scheme which reduce the time and cost of the assay , ii) the fabrication of the device using standard silicon microelectronics technology opening the possibility for mass-production, iii) the high sensitivity demonstrated for the different bioapplications assessed achieving detection limits in the pg/ml range (femtomolar), and iv) the device meets the specific requirements to be miniaturized and integrated in a multiplexed platform. This work opens the door for the integration of this transducer in a lab-on-a-chip device, including the in-coupling/out-coupling of light, a system able to modulate the interferometric signal, and the incorporation of microfluidics channels for multiplexing. Each of these subjects adds a great complexity to the final device, and must be independently developed and optimized in order to be successfully integrated at the final lab-on-a-chip biosensor. Finally, the possibility to detect simultaneously multiple analytes will involve further efforts in developing new optical in and outcoupling as well as new biofunctionalization strategies.
Guix, Noguera Maria. "Nano/micromaterials and motors in (bio)sensing applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/120539.
Повний текст джерелаThe design and characterization of novel miniaturized (bio)sensing platforms and devices modified with different nanomaterials, such as carbon nanotubes or nanowires, have been achieved. These platforms and devices have been applied in the detection of various analytes (e.g. phenol, glucose, oil droplets), in some cases closely related to the previously immobilization of biological entities that confer selectivity and sensitivity to the analytical platform. Regarding batch platforms, screen-printed electrodes (SPE) modified with carbon-nanotubes has demonstrated to be a potential analytical platform for environmental purposes by being applied for phenol detection in case of being modified by tyrosinase enzyme. The characterization of modified SPE by SEM, TEM and Confocal Scanning Laser Microscopy (CSLM) has brought the necessary statistical data over the morphological properties of the nano/micromaterials treated and the distribution of tyrosinase enzyme along the sensor matrix. Several immobilization approaches have been developed and the present system has been integrated in a Flow Injection Analysis (FIA). Additionally, carbon nanotubes modified SPE with gold-silver nanowires has resulted in a non-enzymatic electrochemical glucose sensor, based on the measurement of the current response during the direct glucose oxidation on the electrode surface by chronoimpedance technique (CIT) studies. The development of novel assembled nanoplatform taking advantage of layer by layer depositions from Prussian blue (PB) - cyclodextrin (CD) nanoparticles (NPs) with polyallylamine (PAH) was designed, showing a microcubic supramolecular like organitzation. Such platforms present interesting electrochemical behaviour, as the cathodic and anodic peak currents increased with the number of bilayers, indicating that PB nanoparticles are electrically connected within multilayers. Moreover, the combination of paramagnetic particles with microchip electrophoresis, external magnetic field manipulations, and coupled to EC detection permitted the detection of phenol (as indicator for immunodetection) by using low reagent consumption, in addition to the inherent miniaturization and versatility of such miniaturized system. Phenol detection was achieved by following the hydrolysis of phenyl phosphate by alkaline phosphatase (AP) enzyme linked to the magnetic beads (MBs), which resulted in a very interesting system due to the possibility to renew the immuno-specific support. Finally, an alternative and dynamic analytical platform was developed through the implementation of artificial nano/microscale machines for environmental remediation applications based on the creation of a superhydrophobic outer surface to strongly interact and capture oily liquids has been achieved. The development of different platforms, along with the wide range of nano/micromaterials integrated on them as to improve their analytical performance, have shown good results towards the detection of analytes of interest in health and environmental issues, being envisioned future key components of monitoring systems and other analytic platforms of interest.
Albareda, Sirvent Miguel. "Desenvolupament de biosensors per tecnologia planar per a l'anàlisi agroalimentària." Doctoral thesis, Universitat Autònoma de Barcelona, 2003. http://hdl.handle.net/10803/3178.
Повний текст джерелаEl treball realitzar s'ha portat a terme en dues parts molt diferenciades; en una primera s'han desenvolupat biosensors screen-printing basats en resines epoxi per a l'anàlisi de pesticides i en una segona biosensors screen-printing basats en matrius de sílice (sol-gel) per a la determinació d'àcid màlic i làctic en vins.
Marín, Mancebo Sergio. "Synthesis and applications of nanoparticles in biosensing systems." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3300.
Повний текст джерелаAquests quatum dots han estat utilitzats en un sensors de DNA i amb detecció electroquímica de celules com a marca electroquímica, utilitzant la tècnica de detecció electroquímica directe que s'havia emprat en la determinació de quantum dots.
Different synthesis of nanoparticles was carried out in this thesis, such as cadmium sulphide quatum dots, gold nanoparticles, silver nanoparticles and core-shell nanoparticles (Au-Ag and Ag-Au). These nanoparticles were characterized by different techniques such as optical and especially electrochemical techniques. CdS-QDs (synthesized by arrested precipitation method) were quantified using an electrochemical direct detection method with screen-printed electrodes and a portable potentiostat.
These CdS-QDs were used to label in DNA sensor of hybridization and also to detect HeLa cells using the electrochemical direct method that was used in CdS-QDs determination.
Barreiros, dos Santos Marília. "Development of a multi-electrode impedimetric biosensor: detection of pathogenic bacteria and mycotoxins." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284584.
Повний текст джерелаLa detección de bacterias patógenas y micotoxinas es la clave para la prevención y la identificación de los problemas relacionados con la salud pública y seguridad alimentaria. En esta tesis hemos desarrollado una nueva plataforma de múltiples electrodos (multi-electrodo) para detección impedimétrica de bacterias patógenas y micotoxinas. Nos hemos centrado en la detección de bacterias E. coli O157: H7, ya que son responsable por brotes de origen alimentario graves. Se han caracterizado y estudiado la influencia de la (bio)interfaz del sensor para el desarrollo de un biosensor altamente sensible. Por esta razón, se probaron diferentes estrategias y materiales (óxido de indio - estaño y oro). Todos los pasos fueron completamente caracterizados por medio de múltiples técnicas y los resultados obtenidos mostraron que los biosensores desarrollados tenían una excelente respuesta en términos de sensibilidad y selectividad. Además, se obtuvieron resultados prometedores usando multi-electrodos. Estos fueron fabricados en oro y consistían en múltiples electrodos iguales e independientes que permiten el alto rendimiento y experimentos en paralelo en las mismas condiciones experimentales. Los multi-electrodos fueron caracterizados por varias técnicas de análisis de la superficie y técnicas electroquímicas, confirmando la calidad del proceso de fabricación. Hemos demostrado las capacidades de biosensores del multi-electrodo para la detección de bacterias patógenas utilizando diferentes bio-receptores, incluyendo anticuerpos y péptidos antimicrobianos. También se aplicaron los multi-electrodos para el desarrollo de sensores basados en aptámeros para la detección de micotoxinas. Nos centramos en concreto en el caso de la ocratoxina A (OTA), una de las más abundantes que contaminan los alimentos. Se presentaron dos estrategias para la inmovilización de aptámeros, ambas basadas en la hibridación de la superficie del biosensor a través de oligonucleótidos parcialmente complementarios. Se utilizaron técnicas electroquímicas para caracterizar todas las etapas de funcionalización. El multi-sensor desarrollado es capaz de detectar concentraciones de OTA y los prometedores resultados obtenidos demuestran la aplicación para la detección de micotoxinas y las ventajas de utilizar multi-electrodos.
Prieto, Simón Beatriu. "Desenvolupament de biosensors amb enzims oxidoreductases basats en transductors amperomètrics modificats químicament." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/3210.
Повний текст джерелаLa primera part del treball inclou el desenvolupament de quimiosensors reproduïbles i estables per a la determinació del cofactor NADH, del qual depenen els enzims deshidrogenases, i del compost peròxid d'hidrogen, obtingut com a producte de les reaccions en què participen gran part dels enzims oxidases. Els quimiosensors per a la determinació de NADH s'han basat en l'ús de diferents mediadors d'oxidació-reducció, mitjançant vàries estratègies d'incorporació als sistemes de detecció amperomètrica (en solució, per adsorció sobre la superfície electròdica o en membranes de Nafió, incorporats en matrius polimèriques de compòsits de grafit-epoxi, electropolimeritzats o immobilitzats en membranes de polisulfona). Els quimiosensors basats en membranes de polisulfona han mostrat nombrosos avantatges respecte la resta de quimiosensors desenvolupats. De fet, la polisulfona es presenta en aquest estudi com a un bon material polimèric per al desenvolupament de quimiosensors amperomètrics, atès que aconsegueix evitar els problemes de passivació de la superfície electròdica implícits en la determinació del cofactor NADH, i al mateix temps permet una retenció excel·lent dels mediadors immobilitzats al seu interior, amb una absència total de pèrdues d'aquestes espècies per dissolució. D'altra banda, en relació al desenvolupament de quimiosensors per a la determinació de peròxid d'hidrogen, s'han sintetitzat gels de sílice que incorporen diferents metalls que actuen com a catalitzadors dels processos d'oxidació i reducció del peròxid d'hidrogen. Aquests gels s'han dipositat com a mescles del corresponent xerogel amb acetat de cel·lulosa i polietilenglicol, a fi d'aconseguir membranes que minimitzen les limitacions d'aquest tipus de materials (formació d'esquerdes, absorció d'aigua,...). S'han emprat diferents tècniques d'anàlisi amb l'objectiu de dur a terme estudis de caracterització dels quimiosensors basats en membranes de polisulfona i en xerogels modificats amb metalls.
La segona part del treball es va dedicar al desenvolupament de biosensors basats en diversos enzims oxidoreductases, mitjançant l'ús dels quimiosensors prèviament desenvolupats. Els quimiosensors per a NADH s'han adaptat per al desenvolupament de biosensors per a lactat, basats en la incorporació de l'enzim L-lactat deshidrogenasa en matrius de gels de sílice i en membranes de polisulfona, i de biosensors per a ió amoni, basats en la incorporació de l'enzim glutamat deshidrogenasa en polímers de mediador o en membranes de polisulfona. També es va desenvolupar un biosensor bienzimàtic per a la determinació d'urea, basat en la incorporació dels enzims glutamat deshidrogenasa i ureasa en membranes de polisulfona. D'altra banda, els quimiosensors per a peròxid d'hidrogen s'han emprat per al desenvolupament de biosensors per a glucosa, basats en la incorporació de l'enzim glucosa oxidasa en gels de sílice mitjançant vàries configuracions diferents. Els biosensors desenvolupats han demostrat la capacitat de les membranes de polisulfona i dels gels de sílice per a incorporar enzims. A més, en alguns casos, com el biosensor per a ió amoni, s'han aconseguit unes característiques analítiques excel·lents (sensibilitat elevada, intervals lineals amplis, temps de resposta curts, bona reproductibilitat entre corbes de calibració successives,...).
Finalment, la darrera part del treball es va basar en l'adaptació dels quimiosensors i biosensors desenvolupats, basats en una configuració cilíndrica, a una configuració plana, mitjançant processos de serigrafia, i la seva posterior implementació en sistemes de flux.
The aim of this work was the study of different chemical modifications of amperometric sensors in order to minimise the problems involved in the development of biosensors based on oxidoreductase enzymes, trying to find compatibility between the used chemical modifications and the employed enzymatic immobilisation strategies.
The first part of the work was devoted to the development of reliable and stable chemosensors for the determination of NADH cofactor and hydrogen peroxide, for the further development of dehydrogenase- and oxidase-based biosensors, respectively, since dehydrogenase enzymes are NAD-dependent and most of the oxidase enzymes involve hydrogen peroxide as a reaction product. Chemosensors for the determination of NADH were based on the incorporation of different electron mediators, using several incorporation strategies into the amperometrical detection system (in solution, by adsorption onto the electrode surface or onto Nafion membranes, by incorporation inside polymeric matrices of graphite-epoxy composites, by electropolymerization or by immobilisation inside polysulfone membranes). Chemosensors based on polysulfone membranes have shown many advantages in front of the other developed chemosensors. In fact, polysulfone is presented for the first time as an adequate polymeric material for the development of amperometric chemosensors, since it avoids the fouling surface problems typically involved in the amperometric determination of NADH cofactor, while at the same time allows an excellent retention of the immobilised mediators inside the membrane, without leakage of the immobilised species into the solution. On the other hand, in relation to the development of chemosensors for the determination of hydrogen peroxide, several sol-gels have been synthesised, which incorporate different metals acting as catalysts for the oxidation and reduction processes of hydrogen peroxide. These sol-gels have been mixed with cellulose acetate and polyethyleneglycol in order to be deposited as membranes, minimising the limitations of this kind of materials (cracking, water absorption,...). Different analysis techniques have been used with the aim of characterising the final chemosensors based on polysulfone membranes and metal-modified-xerogels.
The second part of the work was directed towards the development of biosensors based on different oxidoreductase enzymes, using the previously developed chemosensors. Chemosensors for NADH have been used for developing lactate biosensors, based on the incorporation of L-lactate dehydrogenase enzyme inside sol-gel matrices and polysulfone membranes, and ammonium biosensors, based on the entrapment of glutamate dehydrogenase enzyme inside electropolymerized mediators or polysulfone membranes. Furthermore, a urea bienzymatic biosensor was developed, based on the incorporation of glutamate dehydrogenase and urease enzymes inside polysulfone membranes. On the other hand, chemosensors for hydrogen peroxide have been used for developing glucose biosensors, based on the immobilisation of glucose oxidase enzyme in sol-gels using different configurations. Both strategies, based on polysulfone membranes and sol-gels, have shown the ability of these membranes to incorporate enzymes into the biosensor configuration. Additionally, some of the developed biosensors, such as the ammonium biosensor, have achieved excellent analytical characteristics (high sensitivity, wide linear ranges, fast response times, good reproducibility among successive calibration curves,...).
Finally, the last part of this work was based on the application of screen-printing technology for the preparation of the developed chemosensors and biosensors with a planar configuration, and their further implementation in flow systems.
Alcalá, Morales Pilar Lucía. "Ingeniería de anticuerpos aplicada al desarrollo y caracterización de biosensores enzimáticos." Doctoral thesis, Universitat Autònoma de Barcelona, 2003. http://hdl.handle.net/10803/3505.
Повний текст джерелаHasta el momento los únicos activadores descritos de los biosensores basados en enzimas son los anticuerpos y aún se desconoce el mecanismo por el cual se produce esta regulación enzimática. El principal objetivo de este trabajo ha sido determinar el tipo de interacciones moleculares que son necesarias para que se lleve a cabo la modulación de la actividad b-galactosidasa. Especialmente, se pretendía evaluar la necesidad de una unión bivalente para la reactivación y explorar la adaptación de los biosensores b-galactosidasa a la detección de ligandos monovalentes, como antígenos.
Se evaluó la interacción molecular entre un péptido RGD recombinante del virus de la fiebre aftosa, expuesto en la superficie de una proteína portadora y sus receptores en la superficie celular. Como ligandos se utilizaron las integrinas avb3 y a5b1 solubles, así como células BHK21. Los resultados indicaron que ni las integrinas solubles ni aquellas expuestas en las células son capaces de modificar la actividad de sensores enzimáticos que por el contrario son activados por la unión de anticuerpos dirigidos contra el motivo RGD. Adicionalmente, se realizaron otros ensayos para determinar el impacto que podía tener la presentación múltiple de péptidos sobre la eficiencia de la unión a células. En este caso se observó que aumentando el número de segmentos virales mejoraba la unión de las proteínas recombinantes a las células.
Se llevó a cabo el clonaje y producción en Escherichia coli de un fragmento scFv recombinante del anticuerpo monoclonal SD6, dirigido contra un péptido vírico antigénico, expuesto en un modelo de biosensor basado en la enzima b-galactosidasa. Los resultados indicaron que la unión del scFv no causaba ninguna respuesta enzimática mientras que la presencia simultánea del scFv y del fragmento Fab del SD6 daba como resultado una respuesta eficiente pero no aditiva del sensor, cuya actividad enzimática aumentaba hasta en un 200%. Este efecto cooperativo que también se pudo observar cuando se combinaban el scFv y el fragmento Fab de un anticuerpo no homólogo denominado 4C4, nos permitió postular que la reactivación enzimática requiere contactos múltiples y probablemente heterogéneos entre el sensor molecular y los analitos, y que no es necesaria la interacción con ligandos moleculares bivalentes para que se produzca dicha modulación de actividad.
Por último, se evaluaron diferentes sitios tolerantes de la enzima b-galactosidasa para generar enzimas híbridas funcionales que presentaran el fragmento recombinante scFv del anticuerpo monoclonal SD6. La caracterización de las proteínas híbridas obtenidas indicó que al fusionar dicho fragmento al extremo amino-terminal de la enzima, la proteína era estable, mantenía su actividad específica e interactuaba con el antígeno hacia el cual estaba dirigido el fragmento de anticuerpo fusionado. Además la quimera scFv-enzima era activa aún cuando se encontraba unida al antígeno y por lo tanto, se demostró su utilidad como reactivo en ELISA.
One of the applications of protein engineering is the development of molecular biosensors as tools for the detection of substances by means of the interaction between a macromolecule and its ligand. According to this principle, a series of prototypes of enzymatic biosensors have been generated through the engineering of proteins such as alkaline phosphatase, b-galactosidase, b-lactamase and TSP protein from P22 bacteriophage. In all these modified enzymes, immunoreactive peptides acting as probes have been inserted in those permissive sites of solvent-exposed surfaces of each enzyme. Binding with anti-peptide antibodies gives rise to an increase or a decrease in the enzymatic activity in a titre dependent way, what in turn constitutes a simple method for the detection and quantification of molecular species within a complex mixture.
Until now, antibodies are the only described activators of enzyme based biosensors and the mechanism by which this enzymatic regulation takes place is still unknown. The main objective of this work was to determine the type of molecular interactions necessary for the up-regulation of b-galactosidase activity. Specially, it was sought to evaluate the need of a bivalent union for activity modulation and to explore the adaptation of b-galactosidase biosensors to the detection of monovalent ligands, as antigens.
The molecular interaction between a recombinant RGD peptide from foot-and-mouth disease virus displayed on the surface of a carrier protein and its receptors on the cell surface was evaluated. Soluble integrins avb3 and a5b1, as well as BHK21 cells were used. The results indicated that both soluble integrins and cell linked ones were not able to modify the activity of enzymatic sensors that on the contrary are activated by binding of antibodies directed against the RGD motif. Additionally, other assays were carried out to determine the impact that multiple peptide presentation could have on cell-binding efficiency. In this case it was observed that increasing the number of viral segments cell binding to recombinant proteins was improved.
Cloning and production in Escherichia coli of a recombinant SD6 scFv fragment directed against a sensing peptide, displayed on a model b-galactosidase-based biosensor was carried out. The results indicated that scFv-binding did not cause any enzymatic response while the simultaneous presence of scFv and the SD6 Fab fragment results in a non-additive, efficient sensor response, enhancing the enzyme activity up to about 200%. This cooperative effect, which also could be observed by combining SD6 scFv and the non-homologous anti-peptide 4C4 Fab fragment, allowed us to postulate that enzyme up-regulation requires multiple and probably heterogeneous contacts between the sensor molecule and the analytes, and that interaction with bivalent molecular ligands is not necessary for activity modulation to take place.
Lastly, different permissive sites in b-galactosidase enzyme were evaluated to generate functional hybrid enzymes displaying the SD6 scFv antibody fragment. Characterization of the resultant hybrid proteins indicated that when fusing this fragment to the amino terminus of the enzyme, the protein was stable, it maintained its specific activity and interacted with the target antigen against which the fused antibody fragment was directed. The scFv-enzyme chimera was enzymatically active while bound to the antigen and therefore, it was demonstrated its possible application as single-molecule reagent in ELISA.
Lermo, Soria Ana Isabel. "Nous dissenys biomoleculars en genosensors i immunosensors per a la seguretat alimentària." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3303.
Повний текст джерелаEn aquesta tesi es van desenvolupar nous dissenys biomoleculars basats en biosensors electroquímics per a la seguretat alimentària abordant tres aspectes crítics dels dispositius biosensors, que convergeixen cap a la simplificació metodològica: la immobilització orientada del biomaterial, la marcació i la transducció del senyal electroquímic.
Donada l'experiència del nostre grup d'investigació en la fabricació de compòsits de grafit-epoxi (GEC) i els avantatges electroquímics demostrats d'aquest material, es van construir nous transductors electroquímics basats en compòsits rígids per a la immobilització orientada de biomolècules per aconseguir la simplificació metodològica en la detecció de DNA i immunoespècies. Els nous transductors construïts es van basar en: i) biocompòsits de grafit-epoxi modificats en volum amb la proteïna avidina (Av-GEB), i ii) compòsits amb un element magnètic integrat (m-GEC). Els biocompòsits d'avidina constitueixen una plataforma universal per a la immobilització directa orientada de material biològic biotinilat, mitjançant la forta unió avidina-biotina. El propi transductor actua com a reservori de material biològic i es pot renovar amb un simple procediment de polit, obtenint una nova superfície per cada assaig. Els magneto elèctrodes permeten la integració de partícules magnètiques als procediments biosensors per tal de realitzar les reaccions biològiques de biorreconeixement en solució, reduint la complexitat de la matriu de les mostres i preconcentrant l'anàlit, obtenint així, una detecció més sensible.
Es va dissenyar una nova estratègia de detecció de DNA provinent de mostres reals dels bacteris patògens Salmonella i Escherichia coli, mitjançant la incorporació d'encebadors marcats a la mescla de reacció de la PCR. A part d'amplificar la quantitat de DNA, es va aconseguir marcar doblement el producte amplificat amb biotina i digoxigenina, per aconseguir la immobilització posterior a partícules magnètiques recobertes d'estreptavidina o Av-GEB i la unió d'un conjugat enzimàtic (antiDIG-HRP) per a detectar el producte amplificat. Així es van obtenir uns protocols simples, ràpids i molt sensibles. Aquests protocols van proporcionar límits de detecció més baixos en comparació amb la tècnica clàssica de gel d'electroforesi i la PCR quantitativa amb sistema TaqMan.
També es van obtenir resultats molt prometedors incorporant a la PCR un encebador magnètic, encebador unit a partícules magnètiques. Així, es va aconseguir l'amplificació directa a la superfície de les partícules magnètiques, simplificant la metodologia. Aquesta estratègia presenta potencial aplicabilitat per a la detecció directa electroquímica de productes amplificats al termociclador de la PCR.
A l'últim bloc de la tesi es va desenvolupar una estratègia immunosensora simplificada amb detecció electroquímica, en la que l'haptè es va immobilitzar a partícules magnètiques recobertes de grups químics tosil, formant un enllaç covalent amb la molècula de naturalesa haptènica. Amb aquesta estratègia es va aconseguir quantificar l'àcid fòlic en mostres cegues de llet enriquida, obtenint valors de recuperació propers al 100%; i quantificar l'àcid fòlic en mostres reals de llet enriquida, obtenint valors molt propers als indicats a la composició dels productes.
The control of food quality along the food production chain has become of growing interest since the increasing incidence of food poisoning is a significant public health concern for customers worldwide. The development of new analytical methodologies with the advantages of rapid response, selectivity and low-cost is still a challenge for food hygiene inspection. Biosensors offer an exciting alternative to the traditional methods allowing decentralised analysis.
Novel biomolecular approaches in electrochemical biosensing were developed in this thesis. The main features of these novel biosensing devices were focused on the integration of processes and the methodological simplification. These tasks were achieved considering the main critical aspects of biosensors design: the orientated immobilization of the biorecognition element, the labelling process to achieve the analytical signal and finally, the electrochemical transduction.
Novel electrochemical transducers based on graphite-epoxy composites (GEC) were developed. The enhanced electrochemical properties of GEC material has been demonstrated previously in our research group. The novel transducers based on rigid composites were used for the simplified and oriented immobilization of biomolecules such as DNA and immunospecies. The new transducers developed were: i) graphite-epoxy biocomposites bulk-modified with avidin (Av-GEB), and ii) magneto electrodes based on graphite-epoxy composite (m-GEC). Avidin biocomposites can be considered as universal platforms for the oriented immobilization of biotinilated biomolecules, through the strong interaction between avidin and biotin. This biocomposite material acts not only as the electrochemical transducer but also as a reservoir for the biological material, being able to be easily renewed by a polish treatment, obtaining a new surface for each assay. The m-GEC magneto electrodes allow the integration of magnetic particles in biosensing procedures. The biorecognition reaction can thus be effectively performed in solution, reducing the matrix effect of the sample and preconcentrating the analyte, as a result these factors enhance the sensitivity of the detection.
A sensitive, rapid and user-friendly strategy for the genetic detection of the main food pathogens - Salmonella and Escherichia coli- was designed. This approach was based on a double-tagging PCR by using two labelled primers, followed by electrochemical genosensing of the double-tagged amplicon. During PCR, not only the amplification of the genetic material was achieved, but also the double-labelling of the amplicon ends with both biotin and digoxigenin tags, in order to achieve the immobilization of the amplicon on streptavidin-modified beads or Av-GEB electrodes as well as the binding of an enzymatic conjugate (antiDIG-HRP) for the electrochemical detection. Better results were achieved in terms of limit of detection compared with the classic gel electrophoresis as well as quantitative PCR based on TaqMan probes.
Promising results were also obtained with the use of a novel magnetic primer, primer bound to magnetic beads. This approach allows the DNA direct amplification on streptavidin magnetic beads surface. This strategy showed potential applicability for the direct electrochemical detection of the amplified products in the PCR termocycler.
Finally, a simple immunosensing strategy with electrochemical detection was developed. In this case, the haptenic molecule was covalently immobilised on tosylactivated magnetic beads. The utility of this strategy was demonstrated for folic acid detection in spiked milk samples, obtaining recovery values around 100%. Moreover, folic acid was also quantified in real enriched milk samples showing results according to the expected labelled values.
Duocastella, Solà Martí. "Study of the laser forward transfer for the preparation of miniaturized biosensors." Doctoral thesis, Universitat de Barcelona, 2010. http://hdl.handle.net/10803/1784.
Повний текст джерелаThe possibility to print tiny amounts of functional materials in a controllable way is of interest in a large number of applications, for instance in the manufacturing of organic electronics, in the deposition of artificial organs (the so-called organ printing), or in the fabrication of miniaturized devices in areas like biosensing. This has prompted the development of microfabrication techniques capable of depositing such functional materials.
The present work is focused on one of these techniques, particularly on a laser-based direct-writing technique called laser-induced forward transfer (LIFT), in which laser pulses are used to deposit material from a donor film to a receptor substrate. This technique is especially interesting due to the possibility that it offers to print droplets of solutions containing functional materials with a high resolution. Moreover, it has additional advantages such as the capability to work in air (at atmospheric pressure and room temperature), the fact that it is a non-contact technique that avoids contamination problems, and the possibility to combine it with laser micromachining.
In this work, a complete study of the LIFT of liquid solutions is performed in order to achieve a better understanding of this technique and to find the optimum printing conditions. Such study comprises the analysis of the role that some of the most important experimental parameters have on the printed droplets, as well as the analysis of the mechanisms involved in the ejection and deposition of material through LIFT. This is accomplished by means of both the morphological characterization of the printed droplets at different conditions and the time-resolved imaging of the LIFT process, including the ejection and transport of liquid, as well as the deposition of liquid on the receptor substrate. The present work has provided a complete picture of the LIFT process: the experimental conditions adequate for droplet printing have been set up, and the mechanisms responsible for the generation of droplets have been unveiled. The feasibility of the technique for protein printing has also been demonstrated. Moreover, it has also been found that the preparation of the liquid film in thin form is the major problem that the technique faces. This last aspect has motivated the research of a new technique capable of dispensing with the preparation of the liquid film. This novel technique has been successfully developed and tested in this thesis work.
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La present tesi està centrada en una tècnica d'escriptura directa anomenada transferència induïda per làser (amb anglès laser-induced forward transfer, o LIFT), en la qual s'utilitzen polsos làser per dipositar material des d'una pel·lícula donadora a un substrat receptor. Aquesta tècnica és especialment interessant degut a la possibilitat que ofereix per imprimir, amb una gran resolució, gotes de solucions que contenen materials funcionals. A més a més, té avantatges addicionals com ara la capacitat de treballar sense buit i a temperatura ambient, el fet de ser una tècnica que evita problemes de contaminació al no estar en contacte la pel·lícula donadora amb el substrat receptor, i finalment al poder-la combinar amb altres tècniques com ara la micromecanització amb làser.
En aquest treball es presenta un estudi complet de la LIFT per tal d'aconseguir-ne una millor comprensió així com trobar les condicions òptimes d'impressió. Els materials dipositats han estat sempre solucions líquides. L'estudi presentat comprèn l'anàlisi dels efectes que alguns dels paràmetres més importants de la tècnica tenen en la morfologia de les gotes transferides, així com l'anàlisi dels mecanismes involucrats en l'ejecció i dipòsit de material a través de la LIFT. Això s'ha aconseguit mitjançant la caracterització morfològica del material transferit a diferents condicions, així com utilitzant l'adquisició ràpida d'imatges del procés d'ejecció de material i de dipòsit. Aquest treball ha permès obtenir una imatge completa del procés de la LIFT: s'han determinat les condicions adequades per la impressió de gotes, i els mecanismes per a la generació de gotes s'han desxifrat. La viabilitat de la tècnica per a la impressió de proteïnes també s'ha demostrat. A més a més, s'ha trobat que la preparació de la pel·lícula líquida per a la LIFT és el principal inconvenient que té aquesta tècnica. Aquest aspecte ha motivat la recerca d'una nova tècnica capaç d'evitar la pel·lícula líquida. Aquesta nova tècnica s'ha desenvolupat i provat satisfactòriament en aquest treball.
Castillo, Fernández Óscar. "Analysis and characterisation of biological samples in nano and microfluidic devices using AC and DC electric fields." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/97158.
Повний текст джерелаEsta tesis titulada “Analysis and characterisation of biological samples in nano and microfluidic devices using AC and DC electric fields” tiene como objetivo el estudiar los efectos que tienen los campos eléctricos sobre muestras biológicas con el fin de desarrollar herramientas microfluídicas (lab-on-a-chip) para la manipulación y detección de las muestras biológicas. El trabajo está dividido en tres ámbitos orientados a desarrollar dispositivos o módulos en un dispositivo para diagnóstico. En el primer bloque estudiamos el movimiento de moléculas de ADN (-DNA) en el interior de nanocanales de 20 nm de alto bajo la influencia de campos DC y AC. El objetivo es determinar el mecanismo que hay detrás de la separación por tamaño de esta molécula en ausencia de geles y matrices. En el segundo bloque desarrollamos un nuevo sistema dielectroforético de separación celular por tamaño, basado en la competencia entre la fuerza dielectroforética y las fuerzas fluídicas de arrastre. El sistema se utiliza para separar glóbulos rojos de monocitos en condiciones fisiológicas (alta conductividad) y en flujo continuo. En el tercer bloque desarrollamos una instrumentación para un microcitómetro de flujo basado en medidas de impedancia. El sistema electrónico se valida mediante la utilización de un sistema de óptico sincronizado que nos permite relacionar la señal obtenida con el paso de las células sobre el área de detección. Mediante este sistema se ponen aprueba las capacidades de detección, así como la capacidad de distinguir células por tamaño. Finalmente utilizamos el efecto de la focalización hidrodinámica para mejorar las prestaciones de sensibilidad de un sistema de electrodos coplanares.
Lee, Sang Hun. "Theoretical and Experimental Characterization of Time-Dependent Signatures of Acoustic Wave Based Biosensors." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11631.
Повний текст джерелаPérez, Rafael Sandra. "Aplicación de biosensores amperométricos de polisulfona/nanotubos de carbono en el análisis de muestras reales." Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/117538.
Повний текст джерелаThe research reported in this dissertation deals with the development of biosensors based on polysulfone and carbon nanotubes (PS/CNT) membranes. This type of membrane has allowed the easy and rapid immobilization of hormones, antibodies and enzymes onto electrode surface by phase inversion technique. Moreover, the use of CNT provides a composite material with excellent electrical properties, and consequently, the possibility of acting as transducer. Initially, the membrane was first characterized using microscopic techniques such as confocal scanning microscopy (CSLM) and scanning electron microscopy (SEM) to determine its structure, porosity and roughness. In addition, CSLM also permitted to visualize the biomolecules distribution into the composite membrane. In this manner, the deposition of CNT/PS membranes onto screen-printed electrodes allowed the construction of immunosensors for the detection of hCG hormone based on a competitive immunoassay. Afterwards, given the main aim of the present work has been the development and optimization of biosensors for their further application in real samples analysis, PS/CNT membranes have been also used for the construction of enzymatic biosensors. For this purpose, L lactate biosensors have been developed using different strategies and enzymes, and finally, successfully applied in wine and beer samples analysis. In the same manner, enzymatic biosensors for histamine determination have also been developed and its response has been checked towards fish samples. Lastly, also the research work carried out in Tor Vergata University (Rome) is described. This consists in the construction of glucose biosensors with the aim of obtaining ultrasensitive responses due to the “branch point effect”; a competition process between two or more enzymes for the same substrate. In this way, this type of response has been used to develop of enzymatic logic gates capable of giving a binary response depending of analyte concentration.
Cetó, Alsedà Xavier. "Llengües (bio)electròniques aplicades a l'anàlisi i caracterització de begudes." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129917.
Повний текст джерелаOver the last years, there has been an increasing demand of new analytical methods with the high sensitivity and selectivity, and fast response needed to meet new challenges in environmental monitoring, food safety and public health. In this fashion, industry is increasingly focused on fast-response and low-cost methods, as those based on chemical sensors, that may be used for screening or detecting any adulteration or contamination of the products, either during or after its production, or to assess they guarantee quality control standards. In this sense, classical research lines in the field of chemical sensors have focused on the development of ever more selective devices towards a particular species, and sensitive to lower concentrations at the same time. Unfortunately, there are few optimally operating chemical sensors that function without any interference or matrix effect in the required conditions when dealing with real samples analysis. Precisely, the difficulty to obtain sensors with appropriate selectivity and sensitivity for a given analyte has led to the appearance of new strategies such as electronic tongues in order to tackle these problems. These analytical systems are inspired by the sensory ability of taste in mammals, where a few receptors can respond to a large variety of substances. This principle is coupled with complex data treatment analogous to the applied in the brain, which allows to quantify or to classify a large amount of substances. These biomimetic systems, opposed to conventional approaches, are directed towards the combination of low selectivity sensors array response (or cross response features) in order to obtain some added value in the generation of analytical information. One of the recent advances in the design of electronic tongues has been the incorporation of biosensors, in order to tackle new application fields or to improve existing ones. These bioelectronic tongues, as they have been named, are only distinguished from conventional ones in the incorporation of one or several biosensors into the sensor array, normally sharing the same transduction principle to facilitate compatibility. In this context, the work presented herein aims to demonstrate the applicability of these systems towards the analysis and characterization of beverages, specifically towards wine and alcoholic beverages, either for the extraction of qualitative information and its classification or the quantification of analytical parameters of interest, responding in both cases to the needs of each sector. Concretely, its application towards cava wine, brandy, beer and wine has been studied; the most important sectors in terms of alcoholic beverages in our country. Additionally, given the importance that phenolic compounds have achieved in the recent years due to its antioxidant activity, with huge health benefits, the quantification of these compounds has been addressed from both points of view: its global content and the individual discrimination; tackling it using either a classical electronic tongue and a bioelectronic tongue, comparing the benefits of the incorporation of biosensors in the e-tongue array. Lastly, given the difficulties derived in the treatment of the data generated with such systems, specially in the case of voltammetric sensors, much attention has been paid to the development and application of novel processing strategies in order to reduce its complexity and improve the obtained results; besides comparing the different proposed strategies between each other.
Richardson, Mandek. "Theoretical and Experimental Investigations to Improve the Performance of Surface Acoustic Wave (SAW) Biosensors." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5566.
Повний текст джерелаMedina, Sánchez Mariana. "Improved biosensing applications using lab-on-a-chip and other platforms." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129331.
Повний текст джерелаSimple and miniaturized micro / nanofluidic platforms are especially interesting due to their advantages like the reduction of sample and reagent volumes, the decrease of the analysis time, the possibility of portability and the integration of conventional analytical techniques. Furthermore it is important to point out the role that nanomaterials can play in terms of enhancing electrochemical properties after being integrated into the microfluidic platform or even in the electrode, where the detection event will be performed. Combined together, nanotechnology, electrochemistry and microfluidics could provide a really powerful biosensor platform, thus in the present Thesis different microfluidic platforms with integrated electrodes as transducers in biosensing applications were evaluated. General aspects and experimental results are exposed, starting from a General Introduction that describes various aspects related with the use of nanomaterials and lab-on-a-chip technologies as a promising synergy for a wide range of applications. The electrochemical detection of proteins (ex. Apolipoprotein-E, ApoE) by using CdS or CdSe@ZnS Quantum Dots (QDs) as labels has been one of the main objectives of this Thesis. The immunocomplex was performed by using tosylactivated magnetic beads as preconcentration platform into the same microfluidic system. Due to the need to achieve a lower limit of detection of the immunoassays, different strategies for electrochemical signal enhancing are proposed. The first one is the use of a magnetic field to immobilize magnetic beads in a controllable way into a microfluidic channel in order to obtain a stable magnetic plug where the immunoassay is performed. The second strategy is the use of a home-made recycling system. In this part, the increasing signal of QDs is demonstrated by using an external peristaltic pump connected to a microfluidic chip forming a loop system. After this demonstration, a micro-peristaltic pump with integrated valves is also proposed. All the fabrication steps have been optimized and the software for sequential control of the valves also has been developed. Finally, bismuth is used as it is a well-known material that agglomerates with heavy metals. We took advantages of this property for improving the electrochemical signal of QDs, due to the cadmium content that QDs have in their core. Optimization of the bismuth concentration has been done in order to achieve the highest signal. This detection has been performed in batch system as well as in microfluidic mode. In addition, another novel platform for electrochemical determination of a pesticide (atrazine) based on magneto-immunoassay using boron-doped diamond (BDD) electrode is presented. BDD electrode has been modified by electroreduction of potassium tetrachloroplatinate (K2PtCl4) in order to grow platinum nanoparticles (Pt-NPs) onto the electrode surface. The immunoassay was based on a direct competitive assay using horseradish peroxidase (HRP) as enzymatic label and magnetic microparticles as preconcentration platform. A flexible organic double gate Bio-Field Effect Transistor (Bio-FET) developed by inkjet technology onto a flexible substrate is also presented. This kind of organic transducers has important advantages for biosensors in terms of fabrication cost and biocompatibility as well as their integration into microchannels. To demonstrate the applicability of this device in the biological field, its functionalization with a capture antibody, in order to detect a model protein in a label-free mode was performed. The device fabrication, its structure, materials composition optimization, electrical characteristics and other functionalities are also discussed. Finally, the general conclusions are exposed including some opinions / recommendations for further continuation of the research in the field.
Gonzalo, Ruiz Javier. "Desarrollo de biosensores enzimáticos miniaturizados para su aplicación en la industria alimentaria." Doctoral thesis, Universitat Autònoma de Barcelona, 2006. http://hdl.handle.net/10803/3237.
Повний текст джерелаEn la construcción de sistemas integrados cobran especial relevancia las técnicas fotolitográficas ("thin film") y serigráficas ("thick film"). Así, el trabajo que aqui se presenta cuenta entre sus objetivos con el diseño, la producción y la caracterización de transductores miniaturizados, para lo que se recurrirá a estas tecnologías de microfabricación que proporcionan dispositivos de reducido tamaño y una alta reproducibilidad.
Una vez descrita la fase de fabricación de los sensores, en los capítulos siguientes se describe su utilización para la fabricación de biosensores enzimáticos altamente selectivos a glucosa y etanol, de gran interés en la industria vitivinícola. La inmovilización enzimática es probablemente la etapa más influyente en el desarrollo de biosensores. En este caso, los enzimas, alcohol oxidasa, glucosa oxidasa y peroxidasa fueron inmovilizadas mediante dos técnicas diferentes. La primera, atrapando los enzimas en un polimero conductor (polipirrol) y el segundo método, atrapandolos mediante entrecruzamiento ("cross linking").
La caracterización de estos biosensores se llevó a cabo mediante estudios de repetibilidad, reproducibilidad, límite de detección, etc., bajo las condiciones óptimas. Los principales parámetros que influyen en la respuesta del dispositivo fueron optimizados mediante la metodología del diseño de experimentos. Finalmente, se comprobó la viabilidad estos dispositivos puestos a punto mediante su aplicación en muestras de mostos y vinos.
Biosensing technology has undergone a great progress in the last years, due to the application of biosensors to biomedical industry. These technologies are been applied to others industrial sectors such environmental industry and, especially, alimentary industry. The present work explains the development and characterization of different miniaturized enzymatic biosensors to the application into winery industry.
The main techniques to fabricate amperometric micro-transducers are thin and thick film. One of the main objectives of this work are the design, fabrication and characterization of miniaturized transducers. These devices were fabricated by thin and thick film technology. Devices with small size and high reproducibility could be achieved thought both thin and thick film technologies.
Once the fabrication and characterization of these devices have been described, in the following chapters the development of several enzymatic biosensors to determine glucose and ethanol, which are important parameters in winery industry, were detailed.
The enzymatic immobilization is probably the stage more influential in the development of biosensors. In this case, the enzymes, alcohol oxidase, glucose oxidase and horse radish peroxidase, were immobilized by two different techniques, entrapment into conductor polymer (polypyrrole) and immobilized by cross-linking.
The characterization of these biosensors was carried out by the studies of repeatability, reproducibility, limit of detection, etc, under the optimum conditions. The main variables were optimized by the experimental design methodology. Finally, these devices were applied to the determination in real samples, both wine and grape juice.