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Biological activity and/or electrochemistry of membrane proteins, bacteria and bacteriophages in a hybrid-based sol-gel material

Abstract : The work reported in this thesis has been developed at the interface between three disciplines, i.e., electrochemistry, material science and microbiology. The purpose of this research was first to study the activity of bacteria immobilized in silica-based films prepared by the sol-gel process on electrode surfaces. Potential applications concern biosensors, bioreactors and biofuel cells. Electrochemically assisted bacterial encapsulation has been developed, using sol electrolysis to immobilize Escherichia coli in a hybrid sol-gel layer. The combination of silica precursors, chitosan, poly(ethylene glycol) and trehalose allowed preservation of cell membrane integrity and metabolic activity. Electrochemistry was then considered as an analytical method. Shewanella putrefaciens and Pseudomonas fluorescens have been encapsulated in silica-based films and the electron transfer reactions from bacteria to different redox mediators have been monitored. Single-walled carbon nanotubes functionalized with ferrocene moieties and bovine heart cytochrome c have been considered as redox shuttles to facilitate the electron transfer in the non-conducting silica matrix, leading to the elaboration of artificial biofilms. Interestingly, these two classes of mediator, i.e. chemical and biological, led to different substrate sensitivity because of their different mechanism of interaction with the bacteria. Immobilization of membrane associated redox proteins in sol-gel films have been then considered and applied for electrocatalysis. Direct and mediated electrochemical communication has been investigated between the electrode surface and cytochrome P450 (CYP1A2) or mandelate dehydrogenase, respectively, showing the interest of sol-gel to stabilize the bioelectrocatalytic reaction. Finally, the influence of encapsulation in a hybrid sol-gel matrix on the infectivity of bacteriophage [phi]X174 has been studied and the protective effect of polyethyleneimine or glycerol was shown
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  • HAL Id : tel-01750444, version 1

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Wissam Ghach. Biological activity and/or electrochemistry of membrane proteins, bacteria and bacteriophages in a hybrid-based sol-gel material. Other. Université de Lorraine, 2013. English. ⟨NNT : 2013LORR0189⟩. ⟨tel-01750444⟩

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