Développement de dispositifs moléculaires fonctionnalisés par un sidérophore pour la reconnaissance moléculaire spécifique en diagnostic clinique

Abstract : Siderophores wich are naturally complexin iron ( III ) are synthesized and secreted by microorganisms against iron. In bacteria and some yeast, siderophores can be actively transported across the cell membrane through receptors and transport proteins with high activity and specificity. The synthesis of an analogue of ferrichrome ( trihydroxamate siderophore ) was recently reported by Ouchetto et al. which highlighted the active transport of this type of siderophores in C. albicans. In this context, we initiated the development of electrode with surfaces of gold functionalized by a siderophore, and involving self-assembled monolayers, in order to develop molecular devices for potential applications in biological media. One of these goals is to develop a sensor of iron ( III ) with a simple detection and real-time electrochemical type. From a medical point of view, the demand from industries to commerziale diagnostic disposable sensors of iron ( III ) is important : the aim is to develop a mobile device to diagnose excess of iron deficiency in patient. Currently, this essays is done in the laboratory by colorimetric method which is non-transportable and unreliable. Compared to optical methods, electrochemical systems using the self-assembled monolayers on gold surface have a number of advantages such as ease of implementation, speed, low cost of finite systems. In this context, this work revolves around two axes : the synthesis and physicochemical study of complexes of iron ( III )-siderophore. In this study, the ligands are associated with different electroactive units in order to set the surface of sensing applications. Our research has therefore developed in three step : * Development of a molecular engineering to synthesize new siderophores immobilsable with specific steric requirements; * Behavioral analysis and/or structure of these complexes in solution, from measurements of UV-Visible and cyclic voltammetry; * The develompent and characterization of electrode materials for electrochemical and piezoelectric technologies. In this work, we first synthesized two series of siderophores with several substituents. Initially, the first synthesis was performed by peptidic coupling of desferrioxamine B with various activated esters to afford various desferrioxamine B analogues for which optical and electrochemical properties are expected to be different. In the second step, we developed synthesis pathways which give access to two immobilisable ferrichrome analogues functionalized by bithiophene probe and a alkanethiol chain. Then the optical and the electrochemical properties of the obtained ligands were characterized and compared in the presence of Fe ( III ). Finally, we conducted a preliminary study of development of self-assembled monolayer to develop the right conditions of post- functionalization.
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Theses
Biomolecules [q-bio.BM]. Université d'Angers, 2010. French


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Submitted on : Friday, June 10, 2011 - 1:59:46 PM
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Kamal Elouarzaki. Développement de dispositifs moléculaires fonctionnalisés par un sidérophore pour la reconnaissance moléculaire spécifique en diagnostic clinique. Biomolecules [q-bio.BM]. Université d'Angers, 2010. French. <tel-00599305>

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