No description available.

Materials in contact with the biological milieu (biomaterials) spontaneously and nonspecifically adsorb constituent proteins which may lead to unwanted cell adhesion and responses or hinder device performance. These interactions and their related phenomena lead to complications in ~3% of implant surgeries. Thus, resistance to these nonspecific interactions is critical to the performance of many implanted biomaterials and biosensing surfaces. Further, these interactions have widespread importance to industrial materials in contact with biological environments such as food packaging, and agricultural and nautical surfaces. Thin film coatings of antifouling polymers are one of the leading methods for reducing nonspecific interactions. Both polymer composition (chemical composition and molecular weight) and polymer grafting density are the principal determinants of coating performance. For applications requiring specific bioactivity, such as selective ligand-analyte interactions for sensors, the polymer coating must remain antifouling and be amenable to functionalization with capture ligands. Tethered polymer coatings can be made by surface initiated polymerization (“graft-from”) which results in higher density coatings, but complex fabrication limits commercialization and capacity of functionalization with capture ligands. Simpler “graft-to” procedures, where pre synthesized polymers are immobilized to a surface, are more amenable to translation but suffer from inferior antifouling properties due to lower density coatings. New fabrication methods are therefore required to improve both graft-to and graft-from coatings. Herein, the effects of polymer density on material performance are explored and leveraged to produce novel functional surfaces using two classes of polymers, namely amphiphilic and thermoresponsive poly(oligo(ethylene glycol)) methyl ether methacrylate, and zwitterionic, functionalizable poly(carboxybetaine methacrylamide) (pCB), as well as copolymers thereof. Specifically, polymer grafting techniques which exploit grafting density effects on surfaces were developed, leading to surfaces: 1) that are both high-loading and antifouling due to two different grafting densities within bimodal architectures, and (2) with enhanced anti-fouling properties despite being prepared via a “grafting-to” method using shrinkable or expandable substrates. Interestingly, shrinking substrates with antifouling polymers resulted in a novel LSPR biosensor with high translation potential. Chapter 2 describes the pH controlled, one-pot production of two-layer brushes composed of an antifouling dense layer and a high-loading lower density layer where capture ligand immobilization was improved by 6 times compared to a single high density layer. Towards improving fouling and bioactivity of graft-to surfaces, Chapter 3 describes the first demonstration of Graft-then-Shrink where a stretched polystyrene (PS) substrate coated in a thin gold layer modified with thiol-terminated pCB was thermo-shrunk to one sixth in footprint to increase polymer surface coating content for enhanced antifouling properties and the production of micro/nano gold wrinkles to generate a localized surface plasmon resonance (LSPR) active surface. The low-cost sensors can vi detect biomolecular interactions by tracking changes in absorbance in the visible spectrum using ubiquitous plate readers. In Chapter 4, Graft-then-Shrink was extended to elastomeric materials, where thiol terminated polymers were grafted onto solvent swollen silicone via thiol-maleimide click chemistry, producing strongly antifouling materials. Taken together, these developments represent significant advances in the preparation and application of antifouling polymer coatings towards the improvement of antifouling surface properties of medical devices and resulted in the development of a novel, low-cost LSPR sensor without the need for specialized equipment. / Thesis / Doctor of Philosophy (PhD) / When a material, such as a medical implant or sensor, is placed in contact with tissues and biological fluids, biomolecules stick to the exposed surfaces through nonspecific interactions. It is important to minimize nonspecific interactions because they can lead to bacterial infections, inflammation, implant failure and loss of device performance. Coatings to minimize nonspecific interactions therefore remain an active area of research. In this thesis, we explored new methods to create biomolecule and cell repellent coatings of long, chainlike molecules known as polymers grafted onto surfaces. Specific types of polymers, known as antifouling, were particularly effective at reducing these interactions. Although it is important to block nonspecific interactions, many devices require bioactive surfaces through selective interactions. For example, sensors for analysis of blood products require the selective binding of the target ligand with minimal binding of non-target agents. To this end, functionalizable antifouling polymers are often modified with a capture or binding agent corresponding to the target ligand. Polymer coatings which are both antifouling and functionalizable for specific interactions, are called “romantic” because of their selective love of a single interaction. To synthesize these romantic polymer coatings, two main methods have been reported: 1) “grafting-from” where the polymer is grown from the surface, producing a very dense coating, and 2) “grafting-to” where the polymer is synthesized in solution, and then immobilized onto the material surface, which produces coatings of lower density. For antifouling polymer coatings to be as effective as possible, polymers should be tethered densely on the material surface, but to maximize the loading of capture agents, polymer density must be lower to allow for grafting within the layer. Further, the grafting-from method is typically more synthetically challenging hindering commercialization. To improve the selective bioactivity of graft-to and graft-from coatings as well as antifouling properties of graft-to coatings, we present two methods to improve the specific bioactivity of anti-fouling polymer coatings and the first description of Graft-then-Shrink, a method to enhance the antifouling properties of graft-to coatings for medical implants and label-free in vitro sensors. For graft-from coatings, we produced a hierarchical romantic surface that consists of two polymer layers, the lower of which is dense and antifouling, and the upper of which is low-density and can accommodate high-levels of bioactive agents, resulting in a best of both worlds; the density of the layers is controlled by a novel pH controlled polymerization procedure. A method to improve the less labor intensive “grafting-to” strategy was then devised, called “Graft-then-Shrink” where the antifouling polymers are grafted onto a shrinkable material, and then the material is shrunk, leading to an increase in grafted polymer content over grafting-to alone. This method was successfully applied to a heat shrinkable material and an elastomeric silicone material, a common material for medical devices, for improved antifouling properties. Finally, a method for combining the Graft-then-Shrink technique iv with a novel localized surface plasmon resonance (LSPR) biosensor was found, that provides a simple route to access romantic surfaces on high-sensitivity, easy to fabricate LSPR biosensors. Together, these fabrication methods will simplify and expedite the translation of antifouling and romantic surfaces for medical devices and sensors.

<p> Early detection of pathogens in food and water samples is essential in containing and preventing the spread of various diseases, such as campylobacter jejuni or E-coli. In the food processing industry, fast and reliable methods for testing products against contamination would mean faster delivery and better food quality. The pairing specificity of complementary DNA strands provides a highly selective means of detecting pathogens based on their genomic content. Recently, a lot of research has been directed towards the use of mainstream semiconductor technology to build highly sensitive and cheap DNA hybridization sensors. Typically, the gate of a metal-oxide-semiconductor (MOS) transistor is removed, and probe single-stranded DNA molecules are added to the exposed insulator. Complementary DNA hybridization from a solution sample can then be sensed electrostatically by the underlying Field-Effect transistor (FET). </p> <p> The work in this thesis is concerned with the mathematical modeling of FET based biosensors, named BioFETs. Modeling will enable the assessment of the sensitivity of such devices, as well as the potential for using the BioFETs in creating fully electronic microarrays. The mathematical model presented here captures the effects of ionic charge screening of the DNA charges by counterions in the ambient solution, and the effects of surface adsorption that can also aid in the charge screening process. The effects of varying different parameters on the sensitivity of the BioFET are investigated, and the noise contributed by the FET structure is incorporated into the analysis to quantify the expected signal-to-noise ratio (SNR) ofthe BioFET. </p> <p> In order to gain further insight into the operation of the BioFET, linear approximations are applied to the different regions of the BioFET to arrive at an analytic expression that approximates its expected response to DNA hybridization. The approximations are verified by comparing them against the results obtained from the physical model. Finally, different circuit configurations are presented that allow for highly sensitive biosensors to be realized using the BioFET, and a description of a fabricated electronic DNA microarray chip in standard CMOS 0.8 μm is presented. </p> / Thesis / Master of Applied Science (MASc)

No description available.

The biosensing field has grown in importance and research efforts over the last few years for many reasons including point of care sensing devices and possible early detection of diseases in the body. Dopamine sensing is discussed in this paper and the development of a dopamine sensing platform would lead to early detection of diseases linked to its abundance or lack thereof in the brain such as Parkinson's disease. This work focuses on the electrochemical methods of biosensing, specifically dopamine sensing, and this method involves the use of electrodes as its sensing component. Multimaterial electrode-embedded fibers are used as the sensing electrode and the electrode material presented is platinum (Pt). Platinum is employed because of its biocompatibility property. The electrodes are placed in the fiber by the method of convergence fiber drawing and the fiber ends are stripped to expose the electrode for application. To make the proposed sensing platform more cost-effective, the platinum is electrodeposited onto the multimaterial fiber's embedded electrode. We discuss the use of a W/Pt modified electrode and a pure platinum wire in dopamine sensing and demonstrate that Pt is indeed a good candidate for dopamine sensing. The results show that the sensitivity of the W/Pt modified electrode to dopamine is higher than that of a pure Pt wire. This work has shown the promising application of electrodeposition in developing a cheaper flexible biosensing platform and opens up the possibility of the development of wearable flexible smart textile sensors because of the use of flexible multimaterial fibers. / Master of Science / The idea of sensing is important to our world and various scientific developments in this area have improved our way of life as humans. Biological sensing, which is what this thesis focuses on, detects the presence of various substances in the body, and developments in the area of biosensing have led to the creation of devices that can detect diseases or gather general information about a person's anatomical state. There has been increased interest in the detection of dopamine as more studies show that some diseases such as Parkinson's disease are related to the amounts of dopamine present in the brain. In this work, we present a potential platform for sensing dopamine in vitro using electrochemistry. Multimaterial fibers with embedded electrodes capable of measuring dopamine were fabricated using a thermal drawing technique. The electrode material in this fiber is the most important part of the sensing platform as it is what determines how sensitive the fiber is to an analyte. The two main topics discussed in this work are the modification of the electrode material using an electrodeposition technique and the sensing of dopamine with the modified electrode using the electrochemical methods of cyclic voltammetry and differential pulse voltammetry. The material involved in the electrodeposition process is Platinum (Pt) and the results show that platinum is a suitable material for dopamine sensing.

The detection of small molecules in complex sample matrices such as environmental (surface and ground water, sediment, etc.) and biological (blood, serum, plasma, etc.) samples is of paramount importance for monitoring the distribution of environmental pollutants and their patterns of exposure within the population as well as diagnosing and managing diseases. Biosensors have demonstrated a singular ability to sensitively and selectively detect analytes in complex samples without the need for extensive sample preparation and pretreatment. Nature has demonstrated myriad examples of exquisite selectivity in spite of complexity and we seek to take advantage of that attribute in the development of novel biosensing systems. In the work presented here, we have developed both cell- and proteinbased biosensing systems for the detection of hydroxylated polychlorinated biphenyls (OH-PCBs) and protein-based sensing systems for the detection of glucose. In the development of a whole-cell sensing system, the regulatory protein, HbpR, and its associated promoter was used to modulate the expression of luciferase. Additionally, the effector binding domain of HbpR, HbpR-A, was isolated and modified with a solvatochromic fluorophore resulting in a proteinbased sensing system. For the detection of glucose, two different glucose binding proteins were engineered in an effort to tailor their characteristics, such as binding affinity and thermal stability, to develop a rugged, sensitive proteinbased sensing system. We envision that these biosensing systems will find applications in the areas of environmental pollutant monitoring and the management and treatment of diseases such as diabetes.

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 190-202).

Tesis por compendio / [ES] La tesis doctoral se centra en el desarrollo de un hidrogel sensible a analitos, funcionalizado con sondas de ADN, con estructura difractiva como transductor óptico para aplicaciones de diagnóstico in vitro. El primer capítulo incluye una visión general de los diferentes conceptos relacionados con el biosensado, los desarrollos recientes en el mercado del diagnóstico in vitro y, en particular, los biosensores de ADN. Además, se presenta la síntesis y caracterización de hidrogeles, su papel como matriz de soporte en biosensado y las estrategias de inmovilización. Por último, se explican los conceptos básicos de la holografía como nueva estrategia de detección y el papel de las diferentes redes de difracción en la biosensación. A continuación, en el Capítulo 2, se discuten los objetivos de este proyecto. El objetivo de esta investigación es desarrollar hidrogeles que incorporen sondas de ADN y dotarlas de una estructura difractiva para que actúen como transductores ópticos sin etiquetas. Se consideran dos tipos de estructuras difractivas: redes holográficas de relieve superficial (SRG) y redes de transmisión de volumen (VTG). La fase inicial de este trabajo se centró en la optimización de hidrogeles, ajustando su composición para que actuaran como biosensores holográficos. Se seleccionaron acrilamida y bisacrilamida para la preparación del hidrogel mediante reacción de polimerización por radicales libres. Además, para introducir la respuesta del analito en la red de hidrogeles 3D, hubo que investigar y poner a punto diferentes estrategias de inmovilización de biorreceptores. En el capítulo 3, la estrategia optimizada consiste en incorporar directamente sondas de ADN modificadas con acridita mediante copolimerización con monómeros de acrilamida durante la formación del hidrogel. Los hidrogeles funcionalizados con ADN se caracterizaron mediante imágenes de fluorescencia y se exploró su versatilidad mediante la fabricación de microarrays. Por último, el hidrogel optimizado sensible a los analitos se utilizó como plataforma para la preparación de SRG. El capítulo 4 describe otro enfoque adoptado para la funcionalización del hidrogel con sondas de ADN. Se añadió un comonómero de acrilato de propargilo al hidrogel de acrilamida, con el fin de introducir la presencia de residuos alcínicos y facilitar una mayor incorporación de las sondas de ADN. Las sondas de ADN utilizadas tenían grupos terminales tiol y se incorporaron mediante química de clic tiol-eno/tiol-yo, debido a la presencia de enlaces C-C dobles y triples. Con esta estrategia, se demostraron dos enfoques de inmovilización de sondas de ADN: durante y después de la síntesis del hidrogel. Los resultados preliminares mostraron que los SRGs tienen potencial para detectar directamente la hibridación de oligonucleótidos en un formato libre de etiquetas. En el capítulo 5, se optimizó el proceso de grabación de VTGs no inclinados en capas de hidrogel para mejorar el rendimiento del transductor. Tras una cuidadosa evaluación de los parámetros de grabación holográfica, las composiciones de las soluciones de incubación y los tiempos de incubación, las estructuras VTG se grabaron con una buena reproducibilidad, logrando una excelente eficiencia de difracción. Además, se estudió su estabilidad en agua para bioensayos. Por último, se observó que los VTG, modificados con oligonucleótidos, respondían selectivamente hibridándose sólo con la diana complementaria, a la vez que conservaban sus propiedades de difracción. El trabajo de investigación demostró la viabilidad de utilizar redes difractivas en capas de hidrogel como biosensores libres de etiquetas, capaces de detectar sondas de ADN, complementarias a la secuencia inmovilizada, en un medio acuoso. Por último, en el capítulo 6, se analizan comparativamente el rendimiento y la aplicabilidad de los distintos enfoques estudiados y se discuten las perspectivas futuras de los hidrogeles de ácidos nucleicos para la detección holográfica. / [CA] La tesi doctoral se centra en el desenvolupament d'un hidrogel sensible a anàlits, funcionalitzat amb sondes d'ADN, amb estructura difractiva com a transductor òptic per a aplicacions de diagnòstic in vitro. El primer capítol inclou una visió general dels diferents conceptes relacionats amb el biosensado, els desenvolupaments recents en el mercat del diagnòstic in vitro i, en particular, els biosensores d'ADN. A més, es presenta la síntesi i caracterització d'hidrogels, el seu paper com a matriu de suport en biosensado i les estratègies d'immobilització. Finalment, s'expliquen els conceptes bàsics de l'holografia com a nova estratègia de detecció i el paper de les diferents xarxes de difracció en la biosensación. A continuació, en el Capítol 2, es discuteixen els objectius d'este projecte. L'objectiu d'esta investigació és desenvolupar hidrogels que incorporen sondes d'ADN i dotar-les d'una estructura difractiva perquè actuen com a transductors òptics sense etiquetes. Es consideren dos tipus d'estructures difractivas: xarxes hologràfiques de relleu superficial (SRG) i xarxes de transmissió de volum (VTG). La fase inicial d'este treball es va centrar en l'optimització d'hidrogels, ajustant la seua composició perquè actuaren com biosensores hologràfics. Es van seleccionar acrilamida I bisacrilamida per a la preparació de l'hidrogel mitjançant reacció de polimerització per radicals lliures. A més, per a introduir la resposta de l'anàlit en la xarxa d'hidrogels 3D, va caldre investigar i posar a punt diferents estratègies d'immobilització de biorreceptores. En el capítol 3, l'estratègia optimitzada consisteix a incorporar directament sondes d'ADN modificades amb acridita mitjançant copolimerización amb monòmers d'acrilamida durant la formació de l'hidrogel. Els hidrogels funcionalitzats amb ADN es van caracteritzar mitjançant imatges de fluorescència i es va explorar la seua versatilitat mitjançant la fabricació de bioxips. Finalment, l'hidrogel optimitzat sensible als anàlits es va utilitzar com a plataforma per a la preparació de SRG. El capítol 4 descriu un altre enfocament adoptat per a la funcionalització de l'hidrogel amb sondes d'ADN. Es va afegir un comonómero de acrilato de propargilo a l'hidrogel d'acrilamida, amb la finalitat d'introduir la presència de residus alcínicos i facilitar una major incorporació de les sondes d'ADN. Les sondes d'ADN utilitzades tenien grups terminals tiol i es van incorporar mitjançant química de clic tiol-eno/tiol-ino, a causa de la presència d'enllaços C-C dobles i triples. Amb esta estratègia, es van demostrar dos enfocaments d'immobilització de sondes d'ADN: durant i després de la síntesi de l'hidrogel. Els resultats preliminars van mostrar que els SRGs tenen potencial per a detectar directament la hibridació de oligonucleótidos en un format lliure d'etiquetes. En el capítol 5, es va optimitzar el procés de gravació de VTGs no inclinats en capes d'hidrogel per a millorar el rendiment del transductor. Després d'una acurada avaluació dels paràmetres de gravació hologràfica, les composicions de les solucions d'incubació i els temps d'incubació, les estructures VTG es van gravar amb una bona reproducibilidad, aconseguint una excel·lent eficiència de difracció. A més, es va estudiar la seua estabilitat en aigua per a bioensayos. Finalment, es va observar que els VTG, modificats amb oligonucleótidos, responien selectivament hibridant-se només amb la diana complementària, alhora que conservaven les seues propietats de difracció. El treball de recerca va demostrar la viabilitat d'utilitzar xarxes difractivas en capes d'hidrogel com biosensores lliures d'etiquetes, capaces de detectar sondes d'ADN, complementàries a la seqüència immobilitzada, en un medi aquós. Finalment, en el capítol 6, s'analitzen comparativament el rendiment i l'aplicabilitat dels diferents enfocaments estudiats i es discuteixen les perspectives futures dels hidrogels d'àcids nucleics per a la detecció hologràfica. / [EN] The PhD thesis focuses on the development of an analyte-sensitive hydrogel, functionalised with DNA probes, with a diffractive structure as an optical transducer for in vitro diagnostic applications. The first chapter includes an overview of the different concepts related to biosensing, recent developments in the in vitro diagnostics market and, in particular, DNA biosensors. Furthermore, the synthesis and characterisation of hydrogels, their role as a support matrix in biosensing and immobilisation strategies are presented. Finally, the basic concepts of holography as a new detection strategy and the role of different diffraction gratings in biosensing are explained. Then, in Chapter 2, the objectives of this project are discussed. The aim of this research is to develop hydrogels that incorporate DNA probes and provide them with a diffractive structure to act as label-free optical transducers. Two types of diffractive structures are considered: surface-relief holographic gratings (SRGs) and volume transmission gratings (VTGs). The initial phase of this work focused on the optimisation of hydrogels, adjusting their composition to act as holographic biosensors. Acrylamide and bisacrylamide were selected for hydrogel preparation by free radical polymerisation reaction. Furthermore, in order to introduce the analyte response into the 3D hydrogel network, different bioreceptor immobilisation strategies had to be investigated and fine-tuned. In chapter 3, the optimised strategy is to directly incorporate acridite-modified DNA probes by copolymerisation with acrylamide monomers during hydrogel formation. The DNA-functionalised hydrogels were characterised by fluorescence imaging and their versatility was explored by microarray fabrication. Finally, the optimised analyte-responsive hydrogel was used as a platform for SRG preparation. Chapter 4 describes another approach adopted for functionalisation of the hydrogel with DNA probes. A propargyl acrylate comonomer was added to the acrylamide hydrogel in order to introduce the presence of alkyl residues and facilitate further incorporation of the DNA probes. The DNA probes used had thiol end-groups and were incorporated by thiol-ene/thiol-yo click chemistry, due to the presence of double and triple C-C bonds. With this strategy, two approaches to DNA probe immobilisation were demonstrated: during and after hydrogel synthesis. Preliminary results showed that SRGs have the potential to directly detect oligonucleotide hybridisation in a label-free format. In chapter 5, the recording process of unslanted VTGs in hydrogel layers was optimised to improve transducer performance. After careful evaluation of holographic recording parameters, incubation solution compositions and incubation times, the VTG structures were recorded with good reproducibility, achieving excellent diffraction efficiency. In addition, their stability in water for bioassays was studied. Finally, oligonucleotide-modified VTGs were found to respond selectively by hybridising only to the complementary target, while retaining their diffraction properties. The research work demonstrated the feasibility of using diffractive networks in hydrogel layers as label-free biosensors, capable of detecting DNA probes, complementary to the immobilised sequence, in an aqueous medium. Finally, in chapter 6, the performance and applicability of the different approaches studied are comparatively analysed and future prospects of nucleic acid hydrogels for holographic detection are discussed. / I would like to acknowledge the government of Valencia to for the PhD fellowship “Santiago Grisolia” and the BEFPI/2022 grant for a 4-months doctoral stay and also the Spanish Ministry of Economy and Competitiveness MINECO (ADBIHOL national project) for their financial support. / Zezza, P. (2023). Holographic biosensors made of DNA-functionalised hydrogels for in vitro diagnostic [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202597 / Compendio

While the Canadian food supply is among the healthiest in the world, almost 4 million (1 in 8) Canadians are affected by food-borne illnesses, resulting in 11,600 hospitalizations and 238 deaths per year. Microbial pathogens are one of the major causes of foodborne sicknesses that can grow in food before or following packaging. Food distribution is an important part of the food processing chain, in which food supplies are at a higher risk of contamination due to lack of proper monitoring. Among myriad of research around biosensors, current devices focusing on packaged food monitoring, such as leakage indicators or time temperature sensors are not efficient for real-time food monitoring without separating the sample from the stock. Packaged food such as meat and juice are directly in touch with the surface of their containers or covers. Therefore, real-time sensing mechanisms, installed inside the food packaging and capable of tracing the presence of pathogens, are of great interest to ensure food safety. This work involves developing thin, transparent, flexible and durable sensing surfaces using DNA biosensors, which report the presence of a target bacterium in food or water samples by generating a fluorescence signal that can be detected by simple fluorescence detecting devices. The covalently-attached DNA probes generate the signal upon contact with the target bacteria with as low as 103 CFU/mL of Escherichia coli in meat and apple juice. The fabricated sensing surfaces remained stable up to several days under varying pH conditions (pH 5 to 9). In addition to detecting pathogens on packaged food or drinking bottles, these surfaces have the potential to be used for a variety of other applications in health care settings, environmental monitoring, food production chain, and biomaterials like wound dressing. / Thesis / Master of Science (MSc) / Microbial pathogens can grow in food following packaging and preceding consumption. Current biosensors are not efficient for post-packaging real-time food monitoring without separating the sample from the stock. Packaged food such as meat and juice are directly in touch with the surface of their containers or covers. Therefore, real-time sensing mechanisms, installed inside the food packaging, tracing the presence of pathogens, are much useful to ensure the food safety. Here we report on developing thin, transparent, flexible and durable sensing surfaces using DNA biosensors, which generate a fluorescence signal in the presence of a target bacterium in food or water samples. The covalentlyattached DNA probes can detect as low as 103 CFU/mL of Escherichia coli in meat, sliced apple and apple juice. The fabricated sensing surfaces remained stable up to several days under varying pH conditions (pH 5 to 9). In addition to pathogen monitoring in packaged food or drinking bottles, these surfaces are promising for a variety of other applications in health care settings, environmental monitoring, and biomaterials like wound dressing.

There is an ever growing demand for low cost biosensors in medical diagnostics. A well known commercially successful example is glucose biosensors which are used to diagonize and monitor diabetes. These biosensors use electrochemical analysis (electro analysis) as transduction mechanism. Electro analytical techniques involve application of electrical stimulus to the chemical/biochemical system under consideration and measurement of electrical response due to the oxidation and reduction reactions that occur because of the stimulus. They offer a lot of advantages in terms of sensitivity, selectivity, cost effectiveness and compatibility towards integration with electronics. Besides glucose, there are several biomolecules of significance for which electro analysis can potentially be used to develop low cost, rapid, easy to use biosensors. One such biomolecule is Glycated Hemoglobin (GHb). It is a post translational, non-enzymatic modification of hemoglobin with glucose and is a very good biomarker that indicates the average value of blood glucose over the past 120 days. It is always expresses as a percentage of total hemoglobin present in blood. Monitoring diabetes based on the value of percentage Glycated hemoglobin is advantageous as it gives an average value of glucose unlike plasma glucose values which vary a lot on a day to day basis depending on the dietary habits and the stress levels of the individual. This thesis is focused on the development of a low coat, easy to use, disposable sensor for measuring percentage Glycated hemoglobin. The first challenge in developing such a sensor is isolation of hemoglobin. Unlike glucose which is present in blood plasma (liquid content of blood), hemoglobin resides inside red blood cells also known as erythrocytes. O isolate hemoglobin, these cells have to be broken or lysed. All the existing approaches rely on mixing blood with lysing reagents to lyse erythrocytes. Ideal biosensors should be devoid of liquid reagents. Keeping this in perspective, in this thesis, this challenge is addressed by developing two entirely buffer/reagentless techniques to lyse erythrocytes and isolate hemoglobin. In the first technique, cellulose acetate membranes are embedded with lysing reagents and are used for lysing reagents and are used for lysing application. In the second techniques, commercially available nylon mesh nets are modified with lysing reagents to lyse and isolate hemoglobin. These membranes or mesh nets can be easily integrated on top of a disposable strip. After isolating hemoglobin, the next challenge is to selectively detect Glycated hemoglobin. Boronic acid conjugates are known to bind Glycated hemoglobin. Using this principle, a new composite is sysnthesized to specifically detect glc\ycated hemoglobin. The composite (GO-APBA) is a result of functionalization of Graphene Oxide (GO) with 3-aminophenylboronic acide (APBA). Detection of Glycated hemoglobin is achieved by modifying screen printed electrode strips with the synthesized compound, thus taking a step forwards achieving the objective. Since Glycated hemoglobin is always expressed as a percentage of hemoglobin, the next challenge is to detect total hemoglobin. In this thesis a low cost way of detecting hemoglobin is achieved by using GO modified or surfactant modified screen printed electrode strips. Furthermore, the potential interferences that blood plasma can cause in these measurements are eliminated with the help of permselective coatings. Thus using the technologies developed in this thesis, measurements of percentage Glycated hemoglobin can be potentially made on handheld electronic devices akin to glucose meters by using just a drop of blood.