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Theses

Nouveaux matériaux biohybrides multifonctionnels pour la biocatalyse

Abstract : This multidisciplinary thesis at the biocatalysis/nanomaterial interface perfectly aims at designing innovative biohybrid materials by the assembly of inorganic materials the Layered Double Hydroxides (LDH) with enzymes under mild conditions. The first part of this thesis is devoted to the characterization of physico-chemical interactions between the LDH and the fructose-6-phosphate aldolase (FSA) catalyzing the stereoselective C-C bond formation to provide chiral polyols. LDH structures allow the effective confinement of enzymatic systems thanks to their opened two-dimensional structure as well as their chemical surface properties at the nanoscale and their biocompatibility. The FSA immobilization in different LDH matrices by different methods was studied. Biocatalytic activity is highly dependent on the method of assembling, modulating the final amount of FSA. The retaining activity rate of co-precipitated material was higher than that obtained for the adsorbed enzyme. In a second part, a bionanoreactor was developed based on a hierarchized assembly of FSA, LDH nanoplatelets and polysaccharide beads acting as a macrostructuring matrices. Significantly, the encapsulated enzyme rate in the beads was improved when the biocatalyst was pre-encapsulated in LDH nanoplatelets. This is attributed to favorable electrostatic interactions between the polysaccharide chains and LDH, facilitating a higher catalyst loading. The catalytic efficiency of the prepared bioreactor and its recyclability were demonstrated. In the third part of this thesis, we describe for the first time the design of bionanoreactors ―enzymes@LDH‖ by co-immobilisation of two and four enzymes in LDH allowing biomimetic multienzymatic cascades. We first studied the immobilization of the different enzymes taken separately. Then we worked on the optimization of the biocatalytic cascades in heterogeneous phase. These bionanoreactors, for which we have shown the recyclability, have been applied to the synthesis of D-series phosphorylated sugars. Finally, a multienzymatic cascade was de novo designed in aqueous homogeneous solution. It was optimized for the synthesis of rare L-phosphorylated sugars.
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Rima Mahdi. Nouveaux matériaux biohybrides multifonctionnels pour la biocatalyse. Autre. Université Blaise Pascal - Clermont-Ferrand II, 2015. Français. ⟨NNT : 2015CLF22648⟩. ⟨tel-01674166⟩

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