Elaboration de nouvelles matrices d’immobilisation enzymatique à base de Metal-Organic Frameworks pour la dégradation catalytique de polluants environnementaux

The use of enzymes in biocatalytic processes has been a challenging goal over the years. While enzymes present exceptional catalytic properties, their fragility hinders their industrial application. Their stabilization and protection are therefore of paramount importance. This can be effectively addressed through their immobilization within host solid matrices. Traditional materials (silica, clays, polymers, biopolymers, porous carbons…) have been widely studied as supports. Their pure organic or inorganic nature often requires a compromise between affinity with enzymes and robustness of the matrix. Besides, most of them have non-ordered porosity, with non-homogenous pore size distributions, unsuitable for homogeneous immobilization. Metal-Organic Frameworks (MOFs) have been recently introduced as alternative supports, thanks to their hybrid nature and their crystalline and highly porous structures.The aim of this PhD was to combine Metal-Organic Frameworks (highly porous and chemically stable polycarboxylate MOFs) and a mini-enzyme, microperoxidase 8 (MP8) to obtain multifunctional biocatalysts. In a first part, the mesoporous MIL-101(Cr) was used as a host matrix to encapsulate MP8. The encapsulation led to an increased catalytic activity under conditions (acidic conditions, high concentration of H2O2) detrimental to the catalytic activity of MP8, thereby demonstrating the protecting effect of MIL-101(Cr) matrix. The biocatalyst was also efficiently recycled. The selectivity of MP8 for the degradation of the harmful negatively charged organic dye methyl orange was also enhanced, thanks to the charged-based selective adsorption of the dye in MIL-101(Cr) porosity. A second part of the work was devoted to the use of functionalized MIL-101(Cr) analogs. First, functionalized ligands (bearing –NH2 and –SO3H groups) were used, and their influence on MP8 encapsulation was evaluated. The catalytic activity toward sulfoxidation reactions was also studied. The successful encapsulation of MP8 was strongly dependent on charge matching between the enzyme and the MOFs particles, while its catalytic activity was affected by the specific microenvironment of the pores. The MOF frameworks also modified the reactivity of MP8 toward different thioanisole derivatives. Then, a mixed metal MOF (MIL-101(Cr/Fe)), selected for its stable catalytic properties, was synthesized and characterized. Finally, the last part was devoted to the in-situ synthesis of MOFs (microporous MIL-53(Al)-FA) in presence of biomolecules (BSA) under compatible conditions with the preservation of the protein’s quaternary structure (aqueous media and room temperature). The resulting hybrid materials were thoroughly characterized and presented high loadings of BSA. A preliminarily study was performed with the enzyme, Horseradish Peroxidase, which retained its catalytic activity after immobilization.Les enzymes sont des biocatalyseurs de plus en plus utilisés pour la transformation de molécules organiques (chimie fine, bioconversions, dépollution, chimie du pétrole) car elles possèdent de très bonnes sélectivité et réactivité, générant rapidement de larges quantités de produit. Cependant, la fragilité des enzymes, notamment en solution, limite souvent leur utilisation. Il est donc crucial de les immobiliser et de les stabiliser dans des supports adaptés. Une grande variété de matrices d’immobilisation (organiques ou inorganiques) a déjà étudiée, mais aucune ne satisfait pleinement aux critères nécessaires pour le développement de bio-réacteurs (accessibilité au site actif de l’enzyme, relargage de l’enzyme, diffusion des réactifs, recyclabilité, stabilité..). En outre, la majorité de ces matrices présente une porosité désordonnée, inadaptée pour une immobilisation homogène. L’utilisation de matériaux hybrides, cristallins et poreux de type Metal-Organic Frameworks (MOFs) a été récemment proposée comme alternative avec des applications en biocatalyse et en biodétection.Le travail de cette thèse a consisté à associer des matériaux de type Metal-Organic Frameworks à une mini-enzyme, la microperoxidase 8 (MP8), afin d’obtenir des matériaux multifonctionnels. Dans une première partie, le MOF mésoporeux, MIL-101(Cr), a été utilisé pour encapsuler la MP8, ce qui a conduit à une amélioration de son activité catalytique dans des conditions qui ne sont pas adéquates pour l’activité enzymatique (conditions acides, forte concentration en H2O2), démontrant ainsi le rôle protecteur du MOF vis-à-vis de l’enzyme. De plus, il a été possible de recycler le biocatalyseur. Cette approche a également permis d’améliorer considérablement la sélectivité de la MP8 pour la dégradation d’un colorant organique toxique négativement chargé, le méthyl orange, grâce à son adsorption sélective par interaction électrostatique avec les particules de MIL-101(Cr). La seconde partie a été consacrée à l’utilisation de matériaux MIL-101(Cr) fonctionnalisés. Tout d’abord, l’influence de la fonctionnalisation du ligand (avec un groupement –NH2 ou –SO3H) sur l’encapsulation de la MP8 ainsi que sur son activité catalytique pour des réactions de sulfoxydation a été étudiée. Il a été montré que l’activité catalytique et la réactivité de la MP8 sont affectées par le microenvironnement spécifique des pores du MOF, notamment pour des réactions de sulfoxydation mettant en jeu des dérivés thioanisole. Ensuite, un MOF à métal mixte (MIL-101(Cr/Fe)) choisi pour ses propriétés catalytiques stables, a été synthétisé et caractérisé. Enfin, la dernière partie de cette thèse a été consacrée à la synthèse in-situ d’un MOF (le microporeux MIL-53(Al)-FA) en présence de biomolécules (BSA) dans des conditions compatibles avec la préservation de la structure protéique (en solution aqueuse à température ambiante). Les matériaux hybrides obtenus ont été caractérisés en couplant de nombreuses techniques. Cette méthode d’encapsulation a conduit à des taux d’immobilisation extrêmement élevés. Une étude préliminaire a été initiée avec l’enzyme, Horseradish Peroxidase , qui conserve son activité catalytique après immobilisation

Elaboration de nouvelles matrices d’immobilisation enzymatique à base de Metal-Organic Frameworks pour la dégradation catalytique de polluants environnementaux

Les enzymes sont des biocatalyseurs de plus en plus utilisés pour la transformation de molécules organiques (chimie fine, bioconversions, dépollution, chimie du pétrole) car elles possèdent de très bonnes sélectivité et réactivité, générant rapidement de larges quantités de produit. Cependant, la fragilité des enzymes, notamment en solution, limite souvent leur utilisation. Il est donc crucial de les immobiliser et de les stabiliser dans des supports adaptés. Une grande variété de matrices d’immobilisation (organiques ou inorganiques) a déjà étudiée, mais aucune ne satisfait pleinement aux critères nécessaires pour le développement de bio-réacteurs (accessibilité au site actif de l’enzyme, relargage de l’enzyme, diffusion des réactifs, recyclabilité, stabilité..). En outre, la majorité de ces matrices présente une porosité désordonnée, inadaptée pour une immobilisation homogène. L’utilisation de matériaux hybrides, cristallins et poreux de type Metal-Organic Frameworks (MOFs) a été récemment proposée comme alternative avec des applications en biocatalyse et en biodétection.Le travail de cette thèse a consisté à associer des matériaux de type Metal-Organic Frameworks à une mini-enzyme, la microperoxidase 8 (MP8), afin d’obtenir des matériaux multifonctionnels. Dans une première partie, le MOF mésoporeux, MIL-101(Cr), a été utilisé pour encapsuler la MP8, ce qui a conduit à une amélioration de son activité catalytique dans des conditions qui ne sont pas adéquates pour l’activité enzymatique (conditions acides, forte concentration en H2O2), démontrant ainsi le rôle protecteur du MOF vis-à-vis de l’enzyme. De plus, il a été possible de recycler le biocatalyseur. Cette approche a également permis d’améliorer considérablement la sélectivité de la MP8 pour la dégradation d’un colorant organique toxique négativement chargé, le méthyl orange, grâce à son adsorption sélective par interaction électrostatique avec les particules de MIL-101(Cr). La seconde partie a été consacrée à l’utilisation de matériaux MIL-101(Cr) fonctionnalisés. Tout d’abord, l’influence de la fonctionnalisation du ligand (avec un groupement –NH2 ou –SO3H) sur l’encapsulation de la MP8 ainsi que sur son activité catalytique pour des réactions de sulfoxydation a été étudiée. Il a été montré que l’activité catalytique et la réactivité de la MP8 sont affectées par le microenvironnement spécifique des pores du MOF, notamment pour des réactions de sulfoxydation mettant en jeu des dérivés thioanisole. Ensuite, un MOF à métal mixte (MIL-101(Cr/Fe)) choisi pour ses propriétés catalytiques stables, a été synthétisé et caractérisé. Enfin, la dernière partie de cette thèse a été consacrée à la synthèse in-situ d’un MOF (le microporeux MIL-53(Al)-FA) en présence de biomolécules (BSA) dans des conditions compatibles avec la préservation de la structure protéique (en solution aqueuse à température ambiante). Les matériaux hybrides obtenus ont été caractérisés en couplant de nombreuses techniques. Cette méthode d’encapsulation a conduit à des taux d’immobilisation extrêmement élevés. Une étude préliminaire a été initiée avec l’enzyme, Horseradish Peroxidase , qui conserve son activité catalytique après immobilisation.The use of enzymes in biocatalytic processes has been a challenging goal over the years. While enzymes present exceptional catalytic properties, their fragility hinders their industrial application. Their stabilization and protection are therefore of paramount importance. This can be effectively addressed through their immobilization within host solid matrices. Traditional materials (silica, clays, polymers, biopolymers, porous carbons…) have been widely studied as supports. Their pure organic or inorganic nature often requires a compromise between affinity with enzymes and robustness of the matrix. Besides, most of them have non-ordered porosity, with non-homogenous pore size distributions, unsuitable for homogeneous immobilization. Metal-Organic Frameworks (MOFs) have been recently introduced as alternative supports, thanks to their hybrid nature and their crystalline and highly porous structures.The aim of this PhD was to combine Metal-Organic Frameworks (highly porous and chemically stable polycarboxylate MOFs) and a mini-enzyme, microperoxidase 8 (MP8) to obtain multifunctional biocatalysts. In a first part, the mesoporous MIL-101(Cr) was used as a host matrix to encapsulate MP8. The encapsulation led to an increased catalytic activity under conditions (acidic conditions, high concentration of H2O2) detrimental to the catalytic activity of MP8, thereby demonstrating the protecting effect of MIL-101(Cr) matrix. The biocatalyst was also efficiently recycled. The selectivity of MP8 for the degradation of the harmful negatively charged organic dye methyl orange was also enhanced, thanks to the charged-based selective adsorption of the dye in MIL-101(Cr) porosity. A second part of the work was devoted to the use of functionalized MIL-101(Cr) analogs. First, functionalized ligands (bearing –NH2 and –SO3H groups) were used, and their influence on MP8 encapsulation was evaluated. The catalytic activity toward sulfoxidation reactions was also studied. The successful encapsulation of MP8 was strongly dependent on charge matching between the enzyme and the MOFs particles, while its catalytic activity was affected by the specific microenvironment of the pores. The MOF frameworks also modified the reactivity of MP8 toward different thioanisole derivatives. Then, a mixed metal MOF (MIL-101(Cr/Fe)), selected for its stable catalytic properties, was synthesized and characterized. Finally, the last part was devoted to the in-situ synthesis of MOFs (microporous MIL-53(Al)-FA) in presence of biomolecules (BSA) under compatible conditions with the preservation of the protein’s quaternary structure (aqueous media and room temperature). The resulting hybrid materials were thoroughly characterized and presented high loadings of BSA. A preliminarily study was performed with the enzyme, Horseradish Peroxidase, which retained its catalytic activity after immobilization

Metal–Organic Framework Based 1D Nanostructures and Their Superstructures: Synthesis, Microstructure, and Properties

International audienceOwing to their high and tunable porosity as well as great chemical diversity, metal–organic frameworks (MOFs) have shown great promise over the past 20 years for a wide range of applications, including gas storage/separation, catalysis, and biomedicine. To date, MOF nanoparticles (NPs) have mostly been obtained as polycrystalline powders or spherical nanocrystals while anisotropic MOFs nanocrystals have been less explored and are of interest in the fields of catalysis, sensing, and electronics. One of the main challenges for the practical application of MOFs is thus to control the crystal size, morphology, and multiscale porosity of these materials while developing adequate shaping strategies. In this review, we cover recent advances in the different synthetic strategies of one-dimensional (1D) MOF nanocrystals as well as hierarchical porous superstructures based on tubular MOFs. We describe the architectures based on MOFs nanotubes (NTs), nanowires (NWs), and nanorods (NRs). Our discussion is focused on the synthetic approaches that drive the structure, crystallinity, size, and morphology of these hierarchical porous hybrid materials. Finally, their potential for different applications is presented

Enhancing microperoxidase activity and selectivity: immobilization in metal-organic frameworks

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Robust ionic liquid@MOF composite as a versatile superprotonic conductor

International audienceA highly performing proton conducting composite was prepared through the impregnation of EMIMCl ionic liquid in the mesoporous MIL-101(Cr)–SO3H MOF. The resulting EMIMCl@MIL-101(Cr)–SO3H composite displays high thermal and chemical stability, alongside retention of a high amount of EMIMCl even at temperatures as high as 500 K, as well as under moisture conditions. Remarkably, this composite exhibits outstanding proton conductivity not only at the anhydrous state (σ473 K = 1.5 × 10−3 S cm−S) but also under humidity (σ(343 K/60%–80%RH) ≥ 0.10 S cm−1) conditions. This makes EMIMCl@MIL-101(Cr)–SO3H a unique candidate to act as a solid state proton conductor for PEMFC applications under versatile conditions

Moisture-participating MOF thermal battery for heat reallocation between indoor environment and building-integrated photovoltaics

The present deployment of photovoltaic (PV) panels on the rooftop has been far below its potential. Stakeholders often see the PV as a strong design constraint, isolated from the built environment and not adapted to their requirements. Here, we propose a new design that combines the PV panels with a metal-organic framework based sorptive thermal battery, which serves as a multi-functional building element and is more actively involved in the indoor environment regulation. The open-loop thermal battery can stock moisture from air with 105 times its volume so that the built environment with high humidity at night is dried to a comfortable and healthy level. The moisture is removed at daytime with unpleasant solar heat, thereby cools the PV panels simultaneously, improving electricity generation by 5%. The benefits of this design can be translated into economic added value to facilitate investment decisions of building-integrated PV projects

Enzyme Encapsulation in Mesoporous Metal–Organic Frameworks for Selective Biodegradation of Harmful Dye Molecules

International audienceMicroperoxidase-8, a small, peroxidase-type enzyme was successfully immobilized into nanoparticles of the mesoporous and ultra-stable MIL-101(Cr). The immobilized enzyme retained fully its catalytic activity and exhibited enhanced resistance to acidic conditions. The biocatalyst was reusable and showed a long-term stability. By exploiting the properties of the MOF's framework, we demonstrated, for the first time, that the MOF matrix could act in synergy with the enzyme (Microperoxidase-8) and enhance selectivity the oxidation reaction of dyes. The oxidation rate of the harmful negatively charged dye (methyl orange) was significantly increased after enzyme immobilization, most likely due to the preconcentration of the methyl orange reactant due to a charge matching between this dye and the MOF

Is There Any Benefit of Coating Si Particles for a Negative Electrode Material for Lithium-Ion Batteries with Metal–Organic Frameworks? The Case of Aluminum Fumarate

International audienceThanks to its high gravimetric andvolumetric capacities, silicon(Si) is one of the most promising alternatives to graphite for negativeelectrodes for lithium-ion batteries. Its practical use is neverthelesshampered by its low capacity retention, resulting from its high volumevariation upon cycling driving the formation of an unstable solidelectrolyte interphase (SEI). Coatings of Si particles with metal-organicframeworks (MOFs) acting as artificial SEIs were recently reportedand found to lead to improved electrochemical performances in a fewcases. We here developed a room temperature route to coat Si particleswith the aluminum fumarate MOF (Al-fum), in conditions compatiblewith the aqueous formulation of state-of-the-art Si electrodes. Thanksto a variety of characterization techniques, including IR and solid-stateNMR spectroscopies, powder X-ray diffraction, and scanning transmissionelectron microscopy coupled with energy-dispersive X-ray analysis(STEM-EDX), we show that a layer of ca. 20 nm of MOF is grown at thesurface of the Si particles. Nevertheless, such a coating does notranslate into any major modification of the electrochemical performancewhen the Si particles are integrated in electrodes with a loadingof practical interest (& SIM;2 mg(Si) cm(-2)). Postmortem characterizations revealed that Al-fum, although beinghighly stable toward water, evolves in the standard LP30 electrolytethrough a reaction with the PF6 (-) anions.The MOF further reacts during the first electrochemical reduction,ultimately leading to lithium aluminate phases, still located at thesurface of the Si particles. Considering the growing interest of MOFsin the field of electrochemical energy storage, this let us concludethat there is probably a general need to more deeply and systematicallyevaluate the stability of MOFs toward battery electrolytes and electrochemicalprocesses

Producing cold from heat with aluminum carboxylate-based metal-organic frameworks

Worldwide cooling energy demands will increase by four times by 2050. Thermally driven cooling technology is an alternative solution to electric heat pumps in removing hazardous refrigerants and harnessing renewables and waste heat. We highlight the advantages of water-stable microporous aluminum-carboxylate-based metal-organic frameworks, or Al-MOFs, as sorbents in the application of producing cold from heat. Here, we synthesize the Al-MOFs with green and scalable processes, which are prerequisites for exploring various industrial and civil applications. A proof-of-concept full-scale adsorption chiller with different Al-MOFs is built up with optimized configurations derived from various characterization techniques. The tested Al-MOFs achieve thermal efficiency above 0.6 and specific cooling power over 1 kW/kg in typical cooling scenarios. Notably, when solar thermal energy is used as the heat source in an outdoor validation, Al-MOFs are weather-resilient solutions that exhibit a stable energy conversion efficiency under fluctuating operating conditions (ambient temperature and solar irradiation)

Encapsulation of Microperoxidase-8 in MIL-101(Cr)-X Nanoparticles: Influence of Metal-Organic Framework Functionalization on Enzymatic Immobilization and Catalytic Activity

International audienceMicroperoxidase 8 (MP8) was immobilized within MIL-101(Cr) bearing terephthalate linkers with functionalized groups (-NH2 and -SO3H). A synthesis protocol for MIL-101(Cr)-SO3H that avoids the use of toxic Cr(VI) and HF was developed. The electrostatic interactions between the MP8 molecules and the MOF matrices were found to be crucial for a successful immobilization. Raman spectroscopy revealed the dispersion of the immobilized MP8 molecules in MIL-101(Cr)-X matrices as monomers without aggregation. The presence of functional groups resulted in higher amounts of immobilized MP8 in comparison to the bare MIL-101(Cr). The catalytic activity of MP8@MIL-101(Cr)-NH2 per material mass was higher than that for MP8@MIL-101(Cr). The presence of free amino groups can thus improve the immobilization efficiency, leading to a higher amount of catalytically active species and improving the subsequent catalytic activity of the heterogeneous biocatalysts. MP8@MIL(Cr)-X also successfully catalyzed the selective oxidation of thioanisole derivatives into sulfoxides