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Surface functionalization strategies for the design of a lab-on-a-chip integrating an aptamer-based molecular capture for the analysis of emerging water contaminants / Stratégies de fonctionnalisation de surface pour le développement d'un laboratoire-sur-puce intégrant une zone de préconcentration contenant des aptamères pour l'analyse de polluants émergents des eauxPerréard, Camille 25 September 2015 (has links)
Développés pour améliorer la santé et le bien-être, certains composés pharmaceutiques sont désormais sous haute surveillance car considérés comme des contaminants émergents des eaux. Pour répondre à ce nouvel enjeu, nous visons à développer un microsystème d'analyse permettant l'identification et la quantification de ces contaminants dans des échantillons d'eau. L'aspect original de ce microsystème repose sur l'intégration au sein du canal d'une zone de préconcentration dans laquelle sont immobilisés des ligands (aptamères dans notre étude), permettant l'extraction sélective de la cible et sa concentration. Pour développer ce microsystème, deux types de fonctionnalisation de surface doivent être mis en œuvre : (1) globale, sur toute la surface des canaux, pour contrôler leurs propriétés de surface et ainsi éviter l'adsorption et contrôler les écoulements de liquides, et (2) locale, pour greffer les ligands sélectifs dans une zone confinée du canal. Les polymères COC et THV, prometteurs pour la conception de puces microfluidiques grâce à leur transparence dans le domaine UV-visible et leur excellente résistance aux solvants, ont été sélectionnés pour la microfabrication du système. Cependant, leur inertie chimique rend difficile la fonctionnalisation de leur surface, et de nouvelles méthodes de traitement de surface ont été développées. Nous présentons ainsi plusieurs méthodes innovantes pour la fonctionnalisation de ces matériaux, basées sur un dépôt plasma, une modification électrochimique et/ou une réaction chimique. La possibilité d'encapsuler les ligands dans une phase monolithique à l'intérieur d'un microcanal grâce à un procédé sol-gel a également été évaluée. / Developed to promote human health and well-being, certain pharmaceuticals are now attracting attention as crucial emerging water contaminants. To deal with this concern, we aim at developing an analytical microsystem for the identification and quantitation of these contaminants in water samples. The original aspect of this lab-on-a-chip relies on the integration inside the channel of a preconcentration zone in which ligands (aptamer in our study) are immobilized, in order to concentrate the target and extract it from the rest sample matrix. Development of this microsystem requires surface treatments to modify the microchannel surface at two scales: (1) globally (on the entire channel walls) to control surface properties and thus avoid adsorption as well as control fluid flows, or (2) locally to immobilize selective ligands in restricted areas for selective target extraction and preconcentration. Polymers COC and THV, attractive for the conception of microfluidic chips thanks to their UV-visible transparency and high resistance to aggressive solvents, were selected as the microchip material. However due their chemical inertness new functionalization techniques have to be developed to modify their surface. In this work, innovative surface treatment strategies have been developed for both materials, based on plasma, electrochemical and chemical approaches. The possibility of encapsulating aptamers in a monolithic phase inside microchannel by sol-gel process was also explored.
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Um micro flow-batch para determinação fotométrica e turbidimétrica de taninos em amostras de chás / A micro flow-batch for photometric and turbidimetric determination of tannins in tea samplesLima, Marcelo Batista de 10 September 2010 (has links)
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Previous issue date: 2010-09-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study proposed a miniaturized flow-batch system for chemical
analysis. The technique used microfabricated urethane-acrylate, a
commercial polymer. The microsystem was evaluated and optimized by
analysis of synthetic dye samples. Afterwards, it was employed for the
determination of tannins in tea samples. The tannins are a group of
polyphenols of significant relevance in the food industry and
pharmaceuticals. The samples used were green and black tea, obtained
from the local market. The determinations were performed by
turbidimetric methods using copper (II) in an acetate medium, with
photometric methods and ferrous tartrate as a reference. Miniaturization
in urethane-acrylate implies low cost and low maintenance, rapid
prototyping and includes the satisfactory physicochemical properties of
polymer. These characteristics combined with the general advantages of
miniaturization in analytical devices, such as high frequency analysis and
low waste generation, make the system a great source in academic
research. For analysis of tannins in tea samples, the system had precise
and accurate results, and high speeds. This flow-batch microsystem was
able to perform up to 300 tests per hour, for the photometric method of
reference and up to 200 tests per hour for the turbidimetric method. Each
analysis performed generated waste volumes lower than 70 μL. Data
validation of statistical models obtained have proved very satisfactory and
promising for new optical applications. / Neste trabalho de pesquisa foi proposto o uso da técnica de
microfabricação em polímero comercial uretana-acrilato para a
miniaturização de um sistema automático de análises químicas em fluxobatelada,
o flow-batch. O microssistema desenvolvido foi avaliado e
otimizado pela análise de amostras sintéticas de corantes. Posteriormente,
o microssistema, foi empregado para a determinação de taninos, grupo de
polifenóis de expressiva relevância industrial, em amostras de chá verde e
preto, por dois métodos ópticos distintos, fotométrico e turbidimétrico. A
técnica de microfabricação em uretana-acrilato se caracteriza pelos baixos
custos de implementação e manutenção, satisfatórias propriedades físicoquímicas
do polímero e a rápida prototipagem de sistemas microfluídicos.
Tais características aliadas às vantagens inerentes da miniaturização de
dispositivos analíticos, como a elevada frequência de análise e a baixa
geração de resíduos, conferem a esse sistema de análise uma ótima fonte
de pesquisa acadêmica. Para análise dos taninos em amostras de chá, o
sistema apresentou resultados precisos e exatos, além de uma alta
velocidade analítica para ambos os métodos ópticos, sendo capaz de
executar até 300 análises por hora, no método fotométrico e 200 análises
por hora pelo método turbidimétrico. Cada análise efetuada gerou
resíduos cujos volumes foram inferiores a 70 μL. Os dados de validação
estatística dos modelos obtidos se mostraram bastante satisfatórios e
promissores para novas aplicações ópticas.
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