Poon Wai Mei Emily. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 74-81). / Abstracts in English and Chinese. / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1. --- Importance of amino acids --- p.1 / Chapter 1.1.1. --- Clinical samples --- p.1 / Chapter 1.1.2. --- Food samples --- p.2 / Chapter 1.2. --- Reviews of amino acid analysis --- p.6 / Chapter 1.2.1. --- Ion-exchange chromatography --- p.6 / Chapter 1.2.2. --- Gas chromatography --- p.6 / Chapter 1.2.3. --- Thin layer chromatography --- p.8 / Chapter 1.2.4. --- Flow injection analysis --- p.8 / Chapter 1.2.5. --- Liquid chromatography --- p.9 / Chapter 1.2.6. --- Capillary electrophoresis --- p.10 / Chapter 1.2.7. --- Methods of detecting amino acid without derivatization --- p.11 / Chapter 1.3. --- Determination of amino acids by reversed-phase ion-pair chromatography --- p.12 / Chapter 1.4. --- The objectives of the study --- p.15 / Chapter Chapter 2: --- Experimental --- p.16 / Chapter 2.1. --- Materials --- p.16 / Chapter 2.2. --- Apparatus --- p.16 / Chapter 2.3. --- Samples --- p.16 / Chapter 2.4. --- Procedures --- p.17 / Chapter 2.4.1. --- Preparation of amino acid standard solution (stock solutions) --- p.17 / Chapter 2.4.2. --- Method development --- p.17 / Chapter 2.4.3. --- Samples preparation --- p.18 / Chapter 2.4.4. --- Preparation of Dowex column --- p.18 / Chapter 2.4.5. --- Extraction of amino acids from samples --- p.19 / Chapter 2.4.6. --- Recovery test --- p.20 / Chapter Chapter 3: --- Results and Discussions --- p.21 / Chapter 3.1. --- Optimization --- p.21 / Chapter 3.1.1. --- pH --- p.21 / Chapter 3.1.2. --- Ion-interacting reagent --- p.22 / Chapter 3.1.3. --- Organic solvent --- p.29 / Chapter 3.1.4. --- Temperature --- p.34 / Chapter 3.1.5. --- Chromatographic conditions --- p.36 / Chapter 3.2. --- Application --- p.45 / Chapter 3.2.1. --- Precision of injection --- p.45 / Chapter 3.2.2. --- Accuracy of the method --- p.46 / Chapter 3.2.3. --- The concentration of amino acids in food samples --- p.50 / Chapter 3.2.3.1. --- Citrus fruits --- p.50 / Chapter 3.2.3.2. --- Orange juice drinks --- p.60 / Chapter 3.2.3.3. --- Chinese honey --- p.65 / Chapter 3.2.3.4. --- New Zealand honey --- p.67 / Chapter 3.2.3.5. --- Energy drinks --- p.70 / Chapter Chapter 4 : --- Conclusion --- p.72 / Chapter Chapter 5 : --- Bibliographies --- p.74 / Chapter 6. --- Appendices --- p.82 / Chapter 6.1. --- Table 1 : Ingredients of orange juice drinks --- p.82 / Chapter 6.2. --- Table 2 : Honey samples --- p.83 / Chapter 6.3. --- Table 3 : Ingredients of energy drinks --- p.83

Diss. (sammanfattning) Uppsala : Univ., 2003. / Härtill 6 uppsatser.

Over the last decade, immobilization of proteins onto inorganic materials is becoming more crucial to extend a deep understanding of interaction between proteins and nanoparticles. With understanding of the real interaction lying under the protein-nanoparticle relations, it is possible to organize the conformation and orientation of surface and framework species of nanoparticles to generate ideal surfaces for potential biotechnological applications. Due to their unique properties such as large clean surface, tunable surface properties, adjustable surface charge, and dispersibility in aqueous solutions, zeolite and zeo-type materials are one of the remarkable classes of inorganic materials that are widely studied in the literature. These properties make zeolites promising alternative candidates for the immobilization of enzymes and incorporation into biosensing devices. In the current study, a new approach was developed for direct determination of urea, glucose, and butyrylcholine where zeolites were incorporated to the electrode surfaces of a conductometric biosensor and Ion Sensitive Field Effect Transistors were used to immobilize the enzymes. Biosensor responses, operational stabilities, and storage stabilities of the new approach were compared with results obtained from the standard membrane methods for the same measurements. For this purpose, different surface modification technique, which are simply named as Zeolite Modified Transducers (ZMTs) were compared with Standard Membrane Transducers (SMTs). During the conductometric measurements ZMT electrodes were used, which allowed the direct evaluation of the effect of zeolite morphology on the biosensor responses for the first time. It was seen that silicalite added electrodes lead to increased performances with respect to SMTs. As a result, the zeolite modified urea and glucose biosensors were successfully applied for detecting urea and glucose, which can offer improved possibilities to design biosensors. The results obtained show that zeolites could be used as alternatives for enzyme immobilization in conductometric biosensors development. Furthermore, the sensitivities of urease and butyrylcholinesterase biosensors, prepared by the incorporation of zeolite Beta crystals with varying acidity on the surface of pH-sensitive

Les travaux développés dans ce manuscrit de thèse entrent dans le cadre du projet européen intitulé « Hearten », « A co-operative mHealth environment targeting adherence and management of patients suffering from Heart Failure (HF) ». Les acteurs de ce projet cherchent à développer une plateforme réseau multi compétences dont le but est le diagnostic précoce et le suivi des patients atteints d'insuffisance cardiaque. Elle permet l'enregistrement de différents paramètres vitaux de ces patients, comme la pression artérielle, le poids, les biomolécules contenus dans les biofluides, et leur consultation immédiate par les différents acteurs en charge du suivi des patients. L'objectif des travaux de recherche présentés dans ce manuscrit est de développer un capteur de gaz conductimétrique portable et miniaturisé, permettant la mesure en temps réel des VOCs caractéristiques du syndrome HF dans l'air expiré par les patients. La molécule d'acétone, connue dans la littérature pour être l'un des biomarqueurs les plus discriminants d'HF, a été particulièrement ciblée. Le capteur ainsi conçu est formé de paires de microélectrodes interdigitées (µIDEs) en or déposées sur substrat de silicium. La partie sensible du capteur consiste en une membrane polymérique électro-déposée à la surface du capteur qui est sensible à l'acétone. Les paramètres géométriques des µIDES ont été analysés et optimisés au cours de ces travaux afin d'améliorer la réponse et la sensibilité du capteur. Une plateforme d'analyse des gaz contenant l'ensemble de l'instrumentation associée à notre capteur a été développé. Les paramètres de l'instrumentation ont également été analysés et optimisés dans le même but. Nous avons ainsi étudié deux types de membranes polymériques sensibles à l'acétone. La première couche sensible développée est basée sur la co-polymérisation d'un polymère et de nanomatériaux dopants, le chitosan et les zéolites. La seconde couche sensible développée est quant à elle basée sur la co-polymérisation de polypyrrole et de métallophthalocyanines. Le capteur développé présente des performances optimales pour ce projet, dont notamment une limite de détection de l'ordre du ppm, ainsi que des temps de réponse et de recouvrement très courts. L'utilisation de ce capteur dans le cas de mesures cliniques est ainsi très prometteuse puisqu'il permet d'analyser plusieurs échantillons en temps réel, et ceux sur une durée de fonctionnement de plus d'une semaine. Le diagnostic rapide et la prise en charge du patient est donc facilité grâce à ce dispositif, dont les couts de fabrication sont très réduits / The work presented in this manuscript is part of the European project « Hearten », « A co-operative mHealth environment targeting adherence and management of patients suffering from Heart Failure (HF) ». The actors of this project are seeking for developing a multi-competence network platform whose goal is the early diagnosis and follow-up of patients with heart failure. It allows the recording of various vital parameters of these patients, such as blood pressure, weight, biomolecules contained in biofluids, and their immediate consultation by the different actors in charge of patient follow-up.The objective of research presented in this manuscript is to develop a portable conductometric gas sensor, allowing the measurement of characteristic VOCs of HF syndrome in exhaled air by patients. Acetone molecule, known in the literature as one of the most discriminating biomarkers of HF, has been particularly targeted. The sensor thus designed is based on pairs of gold interdigitated microelectrode etched on a silicon substrate. The sensitive part of the sensor consists of a polymeric membrane sensitive to acetone and electro-deposited on the surface of the sensor. The geometrical parameters of the µIDES have been analyzed and optimized during these works to improve the response and sensitivity of the sensor. A gas analysis platform including all the instrumentation associated with our sensor has been developed. The instrumentation parameters have also been analyzed and optimized for the same purpose.We studied two types of polymeric membranes sensitive to acetone. The first sensitive layer developed was based on the co-polymerization of a polymer and doping nanomaterials, chitosan and zeolites. The second sensitive layer developed was based on the co-polymerization of polypyrrole and metallophthalocyanines. The developed sensor provides optimal performance for this project, including a detection limit in the order of ppm level, as well as very short response and recovery times. The sensor can therefore be considered in the case of clinical measurements.The use of this sensor in the case of clinical measurements is very promising because it allows to analyze several samples in real time, and those over a period of operation of more than one week. Rapid diagnosis and patient management is therefore facilitated by this device, whose manufacturing costs are very low

The first part of thesis is theoretical and it is the introduction into conductometry. It defines the essential terms of this field as well as contact and contactless methods of measurement of fluid conductivity and also the influential parasitic phenomena and possibilities of their elimination. The second part is dealing with design of the contactless transformer conductivity probe. The characteristics of designed probe are verified in the practical part of the thesis. The final part of the thesis is dealing with measurement according to the defined points in the assignment. The characteristics of several contact probes are verified and also the characteristic of the contactless transformer probe, which was implemented according to the design from the second part. Outcomes of these measurements establish the suitable power supply frequencies and currents for all these probes.

Les biocapteurs sont des moyens d'analyse en plein essor à la fois rapides, sélectifs et peu coûteux applicables à des domaines extrêmement variés (environnement, santé, agroalimentaire,…). Dans ce type d'outil, un élément sensible de nature biologique (anticorps, enzyme, microorganisme, ADN…) doté d'un pouvoir de reconnaissance pour un analyte ou un groupe d'analytes est associé à un transducteur pouvant être de type électrochimique, optique ou thermique. Dans ce travail, nous nous sommes intéressés au développement de trois biocapteurs utilisant des enzymes de la famille des oxydo-réductases (alcool oxydase, lactate oxydase et formaldéhyde déshydrogénase) pour la détection d'analytes d'intérêt dans le domaine de l'agroalimentaire ou de l'environnement (alcools, lactate et formaldéhyde). Les trois enzymes ont été immobilisées sur des microélectrodes interdigitées en or en vue d'une détection conductimétrique. Nous avons cherché à mieux comprendre le fonctionnement des biocapteurs et optimisé le procédé d'immobilisation des enzymes ainsi que différents paramètres de fabrication ou de mesure afin de maximiser les performances analytiques des outils développés (sélectivité, limite de détection, reproductibilité, stabilité). Nous avons également démontré les potentialités d'application des deux biocapteurs conductimétriques à base de lactate oxydase et de formaldéhyde déshydrogénase pour la détection du lactate dans les produits laitiers et du formaldéhyde dans les eaux / Biosensors are rapid, selective and inexpensive devices that combine a biological recognition element, the so-called bioreceptor (e.g. enzymes, antibodies, DNA or microorganisms) to a physical transducer (e.g. electrochemical, optical, thermal or piezoelectrical). They can be used to detect one specific analyte or one family of analytes for a wide range of applications (e.g. environment, food, health). In this work, we developed biosensors based on three oxidoreductases (alcohol oxidase, lactate oxidase and formaldehyde dehydrogenase) for primary alcohols, lactate and formaldehyde analysis. The three enzymes were immobilized on interdigitated gold microelectrodes in view of conductometric detection. We tried to achieve a better understanding of biosensors processing and optimized enzyme immobilization as well as several fabrication or operational parameters to maximize analytical performances (selectivity, detection limit, reproducibility and stability). We also demonstrated the applicability of both conductometric biosensors based on lactate oxidase and formaldehyde dehydrogenase for the detection of lactate in dairy products and formaldehyde in waters

Les biocapteurs sont des moyens d'analyse en plein essor à la fois rapides, sélectifs et peu coûteux applicables à des domaines extrêmement variés (environnement, santé, agroalimentaire,…). Dans ce type d'outil, un élément sensible de nature biologique (anticorps, enzyme, microorganisme, ADN…) doté d'un pouvoir de reconnaissance pour un analyte ou un groupe d'analytes est associé à un transducteur pouvant être de type électrochimique, optique ou thermique. Dans ce travail, nous nous sommes intéressés au développement de différents biocapteurs, en se basant à l'immobilisation d'enzymes sur des microélectrodes en vue de la détection électrochimique d'analytes d'intérêt dans le domaine environnemental. Nous avons montré les potentialités d'application de deux biocapteurs conductimétrique et impédimétrique à base de lipase Candida Rugosa pour la détection directe et rapide des pesticides organophosphorés. Nous avons cherché à mieux comprendre le fonctionnement des biocapteurs et optimisé le procédé d'immobilisation des enzymes ainsi que différents paramètres de mesure afin de maximiser les performances analytiques des outils développés. Nous avons également élaboré un biocapteur impédimètrique pour une détermination très sensible de la phospholipase A2 en utilisant les nanoparticules d'or afin de renforcer la conductivité électrique. Enfin, nous avons développé un biocapteur de tyrosinase pour la détection du Bisphénol A, en se basant sur la modification électrochimique des électrodes de diamant dopé qui possèdent des propriétés électriques remarquables et uniques, avec l'ajout de nanotube de carbone multi-feuillet, ce qui permet d'améliorer des performances analytiques du biocapteur, en particulier sa limite de détection et sa stabilité. Les biocapteurs à base de lipase et de tyrosinase ont été appliqués avec succès à la quantification des composés organophosphorés et du bisphénol A respectivement dans plusieurs échantillons d'eaux réelles / A biosensor is an analytical device, used for the detection of an analyte, that combines a biological component so-called a receptor (e.g. enzyme, antibody, DNA, microorganism) to a physical transducer (e.g. electrochemical, optical or thermal). In last decade, biosensors are quite promising tools since they are rapid, selective and cost effective, with an increasing interest for their application in various fields (e.g environment, food, health). In this work, we developed different biosensors based on immobilized enzymes onto microelectrodes in view of electrochemical detection. First, we demonstrated the potentialities of conductometric and impedimeteric biosensors based on lipase from Candida Rugosa for direct and rapid detection of organophosphate pesticides. In order to enhance the analytical performances of the developed devices, we tried to optimize enzyme immobilization as well as several operational parameters. We also elaborated an impedimetric biosensor for a sensitive determination of phospholipase A2 activity. Finally, a tyrosinase biosensor was developed for ultra-sensitive detection of Bisphenol A, based on the unique proprieties of boron doped diamond electrodes and taking advantage the use of multi walled carbon naotubes to improve the stability and detection limit of biosensor. We also demonstrated the applicability of both biosensors based on lipase and tyrosinase for the detection of organophosphate pesticides and bisphenol A in river water

Lead-acid batteries are the oldest and most common type of secondary cells. Their biggest use is as a power source for a car starter. Bipolar lead-acid batteries could also be used for new applications such as power sources for hybrid electrical vehicles (HEV) for their high power. But there are still many technical problems limiting its use in these applications, which have to be overcome. This could cover parasite reactions as is gas creation, heat removal from the battery and another big problem is substrate corrosion. This diploma thesis concerns the actual state of bipolar lead batteries in the world with detail orientation to substrate corrosion. This thesis describes the conductometric method of lotion conductivity measurement and its modification for measurement of lead grid conductivity. From that we can find out, that when material loses more conductivity, the greater the corrosion. This thesis describes needed preparative experiments for assurance, that the conductometric method can be used for corrosion speed measurement and there are other experiments testing different lead alloys for corrosion speed.

<p>This thesis concerns the development and utilisation of techniques for characterisation and transdermal delivery of various systems for pharmaceutical applications.</p><p>The degree of dissociation of drug molecules and the mobilities of the different species formed are essential factors affecting the rate of drug delivery by iontophoresis. Hence, determination of drug mobility parameters and equilibrium constants are important for the development of iontophoretic systems. With capillary zone electrophoresis using a partial filling technique and methyl-β-cyclodextrin as chiral selector, the enantiomers of orciprenaline were separated. The association constants between the enantiomers of the drug and the selector were also evaluated. Precision conductometry studies were performed for the hydrochloride salts of lidocaine and 5-aminolevulinic acid in aqueous propylene glycol and water as media, respectively.</p><p>Iontophoresis is a technique for drug delivery where charged molecules are transported into and through skin by application of a weak direct electrical current. The drugs 5-aminolevulinic acid and its methyl ester were used as model compounds and incorporated in two different drug delivery vehicles, a sponge phase and carbopol gel. The bicontinuous structure of the sponge phase, constituted of monoolein and a mixture of propylene glycol and water, makes it interesting for use in iontophoretic delivery, since ions can move more or less freely in the aqueous as well as in the lipid domains. Furthermore, all three components are known for their penetration enhancing abilities. Hydrogels like carbopol gels are interesting media with respect to iontophoretic studies, since devices for iontophoresis often utilize hydrogels as contact interfaces between the skin and the electrodes. The results indicate that the transport achieved iontophoretically using the gel (1 % active substance) was comparable with the passive delivery of clinically used formulations (16 % - 20 % active substance).</p>

This thesis concerns the development and utilisation of techniques for characterisation and transdermal delivery of various systems for pharmaceutical applications. The degree of dissociation of drug molecules and the mobilities of the different species formed are essential factors affecting the rate of drug delivery by iontophoresis. Hence, determination of drug mobility parameters and equilibrium constants are important for the development of iontophoretic systems. With capillary zone electrophoresis using a partial filling technique and methyl-β-cyclodextrin as chiral selector, the enantiomers of orciprenaline were separated. The association constants between the enantiomers of the drug and the selector were also evaluated. Precision conductometry studies were performed for the hydrochloride salts of lidocaine and 5-aminolevulinic acid in aqueous propylene glycol and water as media, respectively. Iontophoresis is a technique for drug delivery where charged molecules are transported into and through skin by application of a weak direct electrical current. The drugs 5-aminolevulinic acid and its methyl ester were used as model compounds and incorporated in two different drug delivery vehicles, a sponge phase and carbopol gel. The bicontinuous structure of the sponge phase, constituted of monoolein and a mixture of propylene glycol and water, makes it interesting for use in iontophoretic delivery, since ions can move more or less freely in the aqueous as well as in the lipid domains. Furthermore, all three components are known for their penetration enhancing abilities. Hydrogels like carbopol gels are interesting media with respect to iontophoretic studies, since devices for iontophoresis often utilize hydrogels as contact interfaces between the skin and the electrodes. The results indicate that the transport achieved iontophoretically using the gel (1 % active substance) was comparable with the passive delivery of clinically used formulations (16 % - 20 % active substance).