Lipase Immobilized within Novel Silica-based Hybrid Foams: Synthesis, Characterizations and Catalytic Properties
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Lipase Immobilized within Novel Silica-based Hybrid Foams: Synthesis, Characterizations and Catalytic Properties Nicolas Brun1,2, Annick Babeau Garcia1, Victor Oestreicher1, Hervé Deleuze2, Clément Sanchez3 and Rénal Backov1 1 Centre de Recherche Paul Pascal, CNRS, Pessac, France. 2 Institut des Sciences Moléculaires, CNRS – Université de Bordeaux, Talence, France. 3 Laboratoire de Chimie de la Matière Condensée de Paris, CNRS – Université Pierre et Marie Curie, Paris, France. ABSTRACT The covalent immobilization of crude lipases within silica-based macroporous frameworks have been performed by combining sol-gel process, concentrated direct emulsion, lyotropic mesophase and post-synthesis functionalizations. The as-synthesized open cell hybrid monoliths exhibit high macroscopic porosity, around 90 %, providing interconnected scaffold while reducing the diffusion low kinetic issue. The entrapment of enzymes in such foams deals with a high stability over esterification and transesterification batch process catalysis. INTRODUCTION Immobilization or entrapment of biocatalysts [1] onto or within porous materials by either physical adsorption [2], covalent attachment [3], inclusion or encapsulation by sol-gel route [4], represent an attractive and efficient approach to facilitate their use in continuous processes. Such systems are expected to enhance stability, activity and selectivity while allowing efficient separation, recycling and reuse of costly enzymes. Thus, design of new functional porous materials to immobilize active biomacromolecules is both of economic and ecologic interests. Recently, as emerged the novel concept of “integrative chemistry” [5], from the interface between bio-inspired approaches and hybrid organic-inorganic chemistry. Through the application of this concept, the assembling of a large variety of molecular precursors or nanobuilding blocks into engineered hierarchical structures should be strongly pre-dictated. Particularly, functional ordered macro-mesoporous materials are of interest for multiple applications in heterogeneous catalysis, separation techniques, purification of wastewaters, sensors, optics etc. With this aim, our research group has developed a way to obtain hybrid macrocellular silica-based monoliths, labeled “Organo-Si(HIPE)” (acronym refers to the High Internal Phase Emulsion process [6]), exhibiting a hierarchically structured porosity in view of reaching final polyfunctionalities [7]. With the same strategy, and using the concept of immobilized biocatalysts, we have just designed a new series of biohybrid foams labelled Lipase@Organo-Si(HIPE), bearing high catalytic performances [8]. EXPERIMENT Synthesis. Si(HIPE) synthesis. Typically, tetraethyl orthosilicate (TEOS; 5 g) was added to an aqueous solution of tetradecyltrimethylammonium bromide (TTAB; 16 g, 35 wt %) previously acidified (7 g of HCl). Hydrolysis was left going on until a monophasic medium was obtained. The oily phase constituted of dodecane (35 g) was then emulsified drop by drop into the hydrophi
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