Magister Scientiae - MSc / "The aim of the study was to use in vitro human whole blood cultures to screen the water samples collected from the Eerste/Plankenbrug river system for cytotoxicity and inflammatory activity and for the first time investigate the impact on the cell- mediated and humoral immune pathways. Water samples were collected fronm the sites during the dry summer season and rainy winter season. Blood was collected from the healthy male volunteers and diluted with RPMI 1640. For cytotoxicity and inflammatory activity 2.5ul of blood for 18-20 hrs at 37 C... This study shows that waster from the Plankenbrug River is heavily polluted by contaminants from both the agricultural area and informal settlement of Kayamandi. These contaminants can be potentially immunotoxic during the summer season and they can result in inflammatory diarrheal disease and immunosuppression in exposed individuals..."

M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Obesity has steadily increased and represents a major public health problem worldwide, reducing quality of life and causing a range of health problems. Obesity has emerged as the fifth leading risk of global deaths. Annually, 2.8 million adults die as a result of being overweight or obese. The increase of obesity remains inexplicable in terms of genetic susceptibility to obesity. The genetic loci identified by genome-wide association studies (GWASs) explains about 2% of the heritability for obesity. Perhaps other factors such as epigenetics may be involved in the increase of obesity and may offer solutions for the management of obesity. Epigenetics is defined as a heritable change in gene expression without altering the genome sequences. It may help in providing a logical explanation between the genome and environment which shapes obesity risk and may help to explain the "missing heritability". Epigenetics may affect two mechanisms, namely: i) DNA methylation,and ii) histone modifications. DNA methylation might give scientists a link to the rise in obesity.The study aimed to investigate the effect of sugars used as sweeteners in sugar-sweetened beverages (SSB) on DNA methylation in a Caco-2 cell line in vitro. Four major objectives were pursued in the study which were to:(1) stimulate the Caco-2 cells with varying concentrations of sugar sweeteners and assess the morphological changes of the cells; (2) evaluate the cytotoxicity of different concentrations of the sugar sweetener on the Caco-2 cell line using the Alamar blue and LDH assay; (3) obtain genomic DNA from the treated Caco-2 cell line and perform bisulfite conversion and rest; and (4) amplify the WT1, MEG3, TNFRSF9, ATP10A, and CD44 obesity-associated genes and ascertain their degree of methylation. Caco-2 cells were stimulated with sugar sweeteners at varying concentrations (low, medium and high) for an incubation period of 62 days,and images of the cells were captured for morphological characterisation. The incubation condition entailed cells plated in a 12 or 96 well plate, incubated in a humidified 5% CO2 incubator at 37 °C and there is nutrient renewal every three days.Alamar blue, a cell proliferation colourimetric assay and lactate dehydrogenase assays (LDH), a homogenous membrane fluorimetric assay were used for the cytotoxicity studies. The results of the characterisation showed that different concentrations of sugar sweeteners affected the morphology of the cells as the incubation period progressed. The cytotoxicity results of both LDH and Alamar blue depicted low concentration of sweeteners that had low-to-moderate toxicity and the medium and high concentration of the sweeteners had a moderate to high toxicity on the Caco-2 cells. DNA from the Caco-2 cells was extracted. Techniques used to study DNA methylation such as bisulfite conversion, PCR amplification and restriction enzymes that have differential sensitivity to 5-methyl-cytosine were performed. The quality of DNA extracted was good. The bisulfite conversion was conducted andno amplification was observed, as a contingency plan Normal PCR was performed to amplify the CpG islands, and there was amplification. In conclusion, the study showed that a low concentration of a sugar sweetener (fructose: glucose) used in beverages had low toxicity to the Caco-2 cell line and prolonged exposure of the low concentration might have an adverse effect on the cells' morphology. At medium concentrations, the sugar sweetener used in beverages had medium toxicity to Caco-2 cells; prolonged exposure may lead to morphological changes. These findings indicated that control of dietary glucose intake is an important strategy in combating the development of obesity and type-2 diabetes. DNA methylation could not be established.

Adding layered double hydroxides (LDHs) to polymer compounds has been shown to make them more resistant to corrosion and improve their physical and chemical properties. However, the main challenge lies in the compatibility between inorganic LDH fillers and organic polymer matrices. The incompatibility between these two is due to differences in polarity and surface properties, which makes dispersion of LDHs within the polymer very difficult, negatively affecting the final material's performance and characteristics. In this work, Zn-Al-NO3 LDH particles were synthesized through co-precipitation method and then modified by decavanadate via the anion exchange process. Then, a silane coupling agent was used to functionalize intercalated LDH particles to make them more hydrophobic; this helped the particles to disperse well inside epoxy coating, which ultimately resulted in better corrosion inhibition performance for the coating. The concentration effect of silane coupling agent on LDHs' surface grafting was also studied using various concentrations of 3-aminopropyltriethoxy silane (APTES). Compositional and structural characterization study on revealed more insight into how the surface treatments worked. Finally, to modify LDHs, sodium dodecyl sulfate was inserted in LDH structure, then APTES molecules were grafted on the dodecyl sulfate intercalated LDHs' surface. These organic intercalation and grafting steps made LDHs more suitable with acrylic resin to form uniform composite mixture through solvent solution mixing. The thermal stability of acrylic coating improved by adding modified hybrid LDH fillers and elevation in decomposition temperature was confirmed using thermogravimetric analysis.

No description available.

Im Rahmen der Studien zur Wirkung von Bleinitrat auf die Embryonalstadien des afrikanischen Welses Clarias gariepinus wurde zunächst der Einfluß der Besamung auf den Härtungsprozess des Chorions untersucht, um die Bedeutung des gehärteten Chorions als Schutzfunktion im Hinblick auf Schadstoffeinwirkung zu klären. Das Studium der Embryonalentwicklung war erforderlich, um das Ausmaß der Änderung der Normalentwicklung unter dem Einfluß von Bleinitrat bewerten zu können. Im Rahmen der toxikologischen Untersuchungen der Wirkung des Bleinitrats auf die Embryonalstadien wurden folgende biologische Marker (Biomarker) betrachtet: Änderungen in der Entwicklung und der Schlüpfrate, morphologische und histologische Änderungen, sowie biochemische Veränderungen (Änderungen von Stoffwechsel-Enzymaktivitäten) und molekulare Veränderungen (Erfassung von DNA-Schädigungen). Die Exposition der besamten Eier mit Bleinitrat führte zu einer Verlängerung der Inkubationszeit und zu starken Mißbildungen. Der Rückgang der Häufigkeiten der Mißbildungen mit der Zeit ließ die Annahme zu, daß die mißgebildeten Embryonen starben. Im Gegensatz zu den morphologischen Mißbildungen wurden histopathologische Effekte nur bei Embryonen gefunden, die den höchsten Dosierungen (300 µg/l und 500 µg/l Bleinitrat) ausgesetzt waren. Nach dem Schlupf war das Muster der Enzymaktivitäten nach Exposition mit Bleinitrat uneinheitlich; die Aktivität von G6PDH nahm zu, die von LDH nahm ab und die von PK zeigte unregelmäßige Fluktuationen. Die Embryonalstadien zeigten signifikante Dosis-abhängige Antworten über die Zeit, da das Ausmaß der DNA-Schädigungen signifikant mit den Bleinitrat Konzentrationen anstieg. Vor dem Schlupf konnten bei den Embryonen nach Bleinitrat Exposition keine Änderungen in den Enzymaktivitäten gefunden werden und nur geringe DNA-Schädigungen, d.h die toxischen Effekte waren sehr gering. Eine Erklärung könnte die schützende Wirkung der Eihülle gegenüber Schadstoffen sein. Die gewählten Biomarker stellen sensitive Detektionsmethoden für Bleinitrat dar. So könnten sie sich als sinnvolle Bioindikatoren für Ägypten erweisen, da dort zunehmend Umweltverschmutzung mit Blei und Bleiakkumulation in Lebensmitteln zu verzeichnen ist. / In order to study the embryo-toxic effects of lead nitrate of the African catfish Clarias gariepinus, we first had to study the effect of fertilization on the hardening process of the chorion to clarify the role of the hardened chorion on the protection of the embryo from the pollutants. Also we had to study the embryonic development of C. gariepinus for providing us with a model for comparison when normal patterns of development are altered due the exposure to lead nitrate. The present toxicological work focuses on lead toxicity in different developmental stages of C. gariepinus considering different biological markers (biomarkers) comprising changes in the development and hatching rate, morphological and histological changes, biochemical changes (alteration of metabolic enzymes activity) and molecular changes (monitoring of DNA damage). Exposure of fertilized eggs to lead nitrate prolonged the incubation period and caused severe morphological malformations. Since the frequencies of the morphological malformations decreased with time, we conclude a lethal impact and selected mortality of abnormal embryos. Unlike the morphological malformation, histopathological changes were only recorded in embryos exposed to the highest dosages (300 µg/l and 500 µg/l lead nitrate). In the post-hatching stages, the patterns of the enzymes activities after lead exposure varied, G6PDH increased, LDH decreased and PK showed fluctuations. Embryonic stages revealed significant dose-related DNA damage response over time, since the degree of DNA damage increased significantly with higher lead concentrations. No specific response in the activities of the selected enzymes and low DNA damage were recorded in the pre-hatching stage after exposure to the lead nitrate doses. This means the lead nitrate had a minute toxic effect on the pre-hatched embryos. We conclude that, low susceptibility in pre-hatching stages is most probably a consequence of the chorion, which seems to protect the embryos from a range of external pollutants. The selected biomarkers were sensitive detection methods for low-level toxicity of lead nitrate. Thus, these are useful tools for biomonitoring, urgently required in Egypt with regard to increasing environmental deposition of lead and bioaccumulation in human food recently observed.

Die genaue physiologische Funktion des zellulären Prion-Proteins (PrPC) ist noch immer nicht vollständig verstanden. Eine mögliche Funktion des PrPC auf das neuronale Überleben nach einem hypoxischen oder ischämischen Insult wird diskutiert. In einem Vorversuch zeigten sich nach zerebraler Ischämie deutlich größere Infarktvolumina in den Gehirnen von Prion-Knock-Out-Mäusen im Vergleich zu denen der Wild-Typ-Mäuse. Das Identifizieren der molekularen Mechanismen der PrPC-vermittelten Neuroprotektion ist daher von großem Interesse und machte die Etablierung eines Zell-Modells erforderlich. Neuere Studien konnten einen Einfluss des zellulären Prion-Proteins auf die Glykolyse nachweisen. Unter Sauerstoffmangelbedingungen kommt es zu einer vermehrten Bildung von Laktat durch das Enzym Laktat-Dehydrogenase (LDH). Neurone benötigen unter hypoxischen oder ischämischen Bedingungen dieses Laktat als Energiesubstrat. Je mehr Laktat den Neuronen zur Verfügung steht, umso höher ist das neuronale Überleben. In dieser Arbeit konnte die Beteiligung der Laktat-Dehydrogenase an der durch das zelluläre Prion-Protein vermittelten Neuroprotektion nach Hypoxie nachgewiesen werden. Das Ziel dieser Arbeit bestand darin, mögliche Unterschiede der LDH-Expression in WT-Zellen, Prnp0/0-Zellen und HEK-293-Zellen unter normalen und hypoxischen Bedingungen in vitro zu untersuchen. Die Expression der LDH war unter hypoxischen Bedingungen in den WT-Zellen im Vergleich zu den Prnp0/0-Zellen deutlich höher. Dies konnte auch in PrPC-überexprimierenden HEK-293-Zellen nach Hypoxie gezeigt werden. Ebenso konnte nachgewiesen werden, dass Hypoxie zu einem größeren Schaden des Tubulinzytoskelettes in Prnp0/0-Zellen führt als in WT-Zellen, was eine neuroprotektive Wirkung von PrPC vermuten lässt. Eine direkte oder indirekte Interaktion von LDH-A und PrPC konnte durch eine Co-Immunpräzipitation in HEK-293-Zellen nachgewiesen werden. Die genauen Mechanismen über die PrPC möglicherweise zu einer vermehrten Laktat-Produktion führt, sind noch nicht eindeutig identifiziert und müssen noch näher untersucht werden. Zusammengefasst kann gesagt werden, dass die erhobenen Daten die Vermutung verstärken, dass das Enzym LDH und sein Produkt Laktat in die durch das zelluläre Prion-Protein vermittelte Neuroprotektion nach Hypoxie involviert sind. Es ist das erste Mal, dass gezeigt wurde, durch welchen Mechanismus PrPC zur Neuroprotektion beiträgt.

L’alliage d’aluminium 2024 est très répandu dans l’industrie aéronautique et automobile. Le processus de corrosion peut entrainer des dommages irréversibles pouvant engendrer des issues fatales dans le domaine aéronautique. Ainsi plusieurs couches de revêtements sont déposées à la surface du métal à protéger pour prévenir le processus de corrosion. Depuis le début du 20ième siècle, le chrome hexavalent (CrVI) a été largement utilisé comme inhibiteur de corrosion dans les différentes couches du revêtement (prétraitement, primer et top-coat). La toxicité de ce composé envers l’homme et l’environnement a entrainé son interdiction et donc son remplacement comme agent de protection. Le confinement d’agent anticorrosif dans des nano-conteneurs a ainsi été reporté puisqu’un effet auto-réparant, en relargant sur demande, peut-être apporté : l’inhibiteur de corrosion agit quand le dommage apparait. Cette étude est focalisée sur l’utilisation de matériaux de type Hydroxydes Doubles Lamellaires (HDL) comme réservoir d’inhibiteurs de corrosion en raison leur propriété d’échange. Dans ce travail, plusieurs molécules ont été étudiées comme potentiel inhibiteur de corrosion. Celles-ci ont été tout d’abord caractérisées par DC-polarisation afin de déterminer la nature de leur comportement inhibiteur (anodique, cathodique ou les deux). Ensuite, ces agents anticorrosifs ont été intercalés dans des matrices HDL et leur capacité de relargage ainsi que leur comportement face au processus de corrosion ont été étudiés. Les particules HDL ainsi obtenues ont été dispersées dans la formulation d’un revêtement primaire et déposé directement sur l’alliage aluminium 2024. La résistance à la corrosion a été suivie par spectroscopie d’impédance complexe. Les propriétés d’auto-protection de notre revêtement (relargage d’agent anticorrosive encas de dommage) et leur propriété barrière, apportée par la morphologie lamellaire des nano-conteneurs, entrainant une diminution de la perméabilité aux espèces agressives (ex. eau, O2, électrolyte) responsable de l’apparition de cloques sur les revêtements, ont ainsi été caractérisées. / Aluminum alloy 2024 is widely used in aircraft and automotive industry. Corrosion processes can provide irreversible damage on the metal substrate which could have a tragic issue in the aircraft domain. Thus, several coating layers have been applied on the metal substrate to prevent corrosion process. Since the beginning of the 20th century, hexavalent chromate compounds have been extensively used as corrosion inhibitor agents for paint, primer and conversion coating. The toxicity for human health and environment has led to replace such compounds. The literature has reported different possibilities to replace such unfriendly compounds. Moreover, the entrapment of corrosion inhibitors in nanocontainer provides a self-healing effect by releasing, on demand, the active species when damage occurs. This study focuses on Layered Double Hydroxide (LDH) material as reservoir due to its exchange properties. This study has characterized several potential corrosion inhibitor molecules by DC-Polarization to determine the nature of the inhibitor compound (i.e. anodic, cathodic or both of them). Further, active anticorrosive species have been intercalated into LDH framework. Then, the release of inhibitor agents and their subsequent behaviour toward corrosion inhibition have been evaluated. Modified LDH materials have been further dispersed in the primer coating formulation and applied on aluminum alloys 2024 substrate. Corrosion inhibition has been followed by electrochemical impedance spectroscopy experiments on scratched and unscratched panel which have permitted to evaluate the self-healing property of these modified LDH materials when damage occurs and the barrier property provided by the lamellar morphology of the inorganic reservoir that is found to decrease the permeation by enhancing the tortuosity of the coating layer towards aggressive species (i.e. water, O2, electrolyte) responsible of the blistering phenomenon.

The reversible and topotactic insertion of guest species within layered host lattices, known as intercalation is a widely studied phenomena. The Layered Double Hydroxides (LDHs) or Anionic Alloys are important class of layered solids with its own distinct ion-exchange host-Guest Chemistry. The LDH structure may be derived from that of Brucite, Mg(OH)2, by random isomorphous substitution of Mg2+ ions by trivalent cations like Al3+, Ga3+ etc. This substitution leaves an excess positive charge on the layers, which is compensated by interlamellar anions. These ions are exchangeable and thus new functionalities can be introduced to ion exchange reactions. Insertion of neutral, non-polar or poorly water-soluble guest molecules remains a challenge. In the present study, two methodologies were adopted to extend the host-guest chemistry of LDHs to neutral and non-polar species, first by using Hydrophobic interaction and second, charge transfer (CT) interaction as driving force. Hlydrophobic interaction as driving force involves functionalization of the Mg-Al-LDH galleries as bilayers, thus covering the essentially hydrophilic interlamellar space of the LDH to one that is hydrophobic and able to solubilize neutral molecules like Anthracene. CT interaction as driving force, involves pre-functionalization of the galleries of the LDH with a donor species e.g. 4-aminobenzoic acid by conventional ion exchange methods to form a LDH-donor intercalated compound. This compound can selectively adsorb acceptor species like Chloranil, Tetracyanoquinodimethane etc. into the interlamellar space of the solid by forming donor-acceptor complexes. The confined donor-acceptor complexes have been characterized by X-Ray Diffraction, UV-Visible, Fourier Transformed Infra-Red and Raman Spectroscopy, Molecular Dynamics Simulations were able to reproduce the experimental results. One dimensional gold nanostructure like nanorods (AuNRs) have received great attention due to their size dependent optical properties, Extending these applications requires assembling the AuNRs into one-, two- and if possible three-dimensional architectures. Several approaches have been developed to assemble AuNRs in two-orientation modes namely end-to-end and side-to-side. The present study self-assembly of the AuNRs has been achieved by anchoring β-cyclodextrin (β-CD) cavities to the nanorods surface. The host-guest chemistry of β-CD has been exploited to assemble the AuNRs. Our strategy was to use a guest molecule that is capable to link β-CD into 1:2 host-guest fashions to link up two β-CD capped nanorods. The guest molecule chosen for the present study was 1,10-phenanthroline. Linkage between the ends of rods leading to V-shaped rods dimmer assembly and side-to-side assembly was achieved by varying the extent of cyclodextrin capping of the AuNRs followed by the addition of linker, 1,10-phenanthroline. The formation of the assembly was characterized using UV-Visible-Near-IR Spectoscopy and Transmission Electron Microscopy.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-10T12:37:20Z No. of bitstreams: 1 deysegomesdacosta.pdf: 10386782 bytes, checksum: a18ce8ca7fd4c235c246f70bc4f6f946 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T15:04:53Z (GMT) No. of bitstreams: 1 deysegomesdacosta.pdf: 10386782 bytes, checksum: a18ce8ca7fd4c235c246f70bc4f6f946 (MD5) / Made available in DSpace on 2017-05-17T15:04:53Z (GMT). No. of bitstreams: 1 deysegomesdacosta.pdf: 10386782 bytes, checksum: a18ce8ca7fd4c235c246f70bc4f6f946 (MD5) Previous issue date: 2011-07-29 / Os hidróxidos duplos lamelares (HDL) ou compostos tipo-hidrotalcita vêm sendo muito estudados devido a suas inúmeras aplicações. No campo da catálise, estes compostos podem atuar como catalisadores, suportes para catalisadores ou precursores de catalisadores. É sabido que a morfologia do suporte tem grande influência sobre a dispersão, a atividade e a seletividade apresentada pelo catalisador. Nestes caso, o conhecimento detalhado dos efeitos do suporte e dos sítios catalíticos exigem a compreensão da estrutura do HDL. Entretanto, por causa da desordem estrutural, muitas vezes inerente ao material, torna-se a determinação completa da estrutura, via difração de raios X, raramente possível. As bandas largas presentes na análise do IV, fazem a atribuição das mesmas ambígua. Devido à complexidade dos HDL e à dificuldade de se adquirir ou interpretar os resultados experimentais, foi proposto um modelo para simular as características estruturais dos compostos tipo-hidrotalcita com o politipo 3R1, usando condições periódicas de contorno e cálculos ab initio dentro da teoria do funcional da densidade (DFT). As informações estruturais da hidrotalcita, obtidas experimentalmente, foram usadas para verificar a validade do modelo teórico. Os resultados mostraram boas concordâncias com os padrões de raios X do pó experimentais. O espectro na região do infravermelho, a entalpia e energia livre de Gibbs, também foram calculadas. Os cálculos de frequências vibracionais mostraram que as moléculas de água intercaladas são altamente organizadas devido às fortes interações intermoleculares com outras moléculas de água, com ânions interlamelares e com as hidroxilas das lamelas. A presença destas interações é refletida na presença do estiramento O-H das moléculas de água deslocadas para baixas frequências. A perda da degenerescência dos modos vibracionais v3 e do v4 foi observada, indicando a redução da simetria do íon carbonato. As modificações termodinâmicas e estruturais resultantes da substituição do íon presente no HDL Zn-Al-Cl também formam analisadas. O íon Cl- do HDL precursor foi trocado por uma série de ânions como o F-, Br-, OH-, NO3-, ClO4-, CO32- e SO42-. Os resultados mostraram que a intercalação do HDL com diferentes íons, afeta o gap de energia e a basicidade da lamela tipo-brucita. A entalpia e a energia livre de Gibbs, a densidade de estados (DOS) e a densidade de estados projetada (PDOS) foram avaliadas para todos os HDL. / The layered double hydroxide (LDH) or hydrotalcite-like compounds have been widely studied due to many applications they have. In catalysis field these compounds can act as catalyst, catalyst support or precursor for supports and catalysts. It is well known that the support morphology has larger influence on the dispersion, activity and selectivity of catalysts. In this case, detailed knowledge about support effects and catalytic sites requires understanding the LDH structure. However, because of the inherent structural disorder, complete structure determination using X-ray diffraction is rarely possible. The IR analysis present broad bands, which makes their assignment ambiguous. Due to the complexity of the LDH and the difficult of acquiring experimental data, we proposed a model to simulate structural features of the hydrotalcite-like compounds with 3R1 polytypes using periodic boundary conditions and ab initio density functional theory (DFT) calculations. The structural information of hydrotalcite from experiments were used to verify the validity of theoretical model. Our results showed good agreements to the powder X-ray patterns. The infrared spectroscopy, enthalpy and Gibbs free energy, also was calculated. The IR calculations showed that intercalated water molecules are highly ordered due the strong intermolecular interactions with other water molecules, interlayer anions and layer hydroxyls. These interaction is reflected by the presence of downshift vibrational frequencies of OH-stretching of interlayer water. The loss of degeneracy of the v3 and v4 vibrational modes are observed, indicating the reduction of the carbonate anion symmetry. The thermodynamic and structural modifications derived from anion exchange on a LDH containing Zn-Al-Cl was also analyzed. The Cl- ion to the LDH precursor was exchanged for a series of anions as F-, Br-, OH-, NO3-, ClO4-, CO32- and SO42-. The resulted show that intercalation of LDH with different anions affect their gap energy and basicity of brucite-like layer. The enthalpy and Gibbs free energy, density of charge, density of state (DOS) and projected density of state (PDOS) were evaluated for all substituted materials.

Ces travaux de thèse pluridisciplinaires à l‘interface entre biocatalyse et nanomatériaux visent la conception de matériaux biohybrides innovants par assemblage dans des conditions douces de matériaux inorganiques de type hydroxydes doubles lamellaires (HDL) avec des enzymes. La première partie de ce mémoire est consacrée à la caractérisation des interactions physico-chimiques entre les HDL et la fructose-6-phosphate aldolase (FSA) catalysant la formation stéréosélective de liaisons C-C pour conduire à des polyols chiraux. Les structures lamellaires HDL permettent un confinement efficace de systèmes enzymatiques grâce à leur structure bidimensionnelle poreuse, leurs propriétés physico-chimiques favorables à l‘échange ionique et leur biocompatibilité. Différentes stratégies d‘immobilisation de la FSA dans des matrices d‘HDL ont été explorées, le taux d‘immobilisation et l‘activité biocatalytique étant fortement dépendant de la méthode d‘assemblage et de la nature des phases HDL. Le taux d‘immobilisation de l‘enzyme obtenu par coprécipitaton est supérieur à celui obtenu par adsorption. Dans une deuxième partie, un bioréacteur a été élaboré par un assemblage hiérarchisé constitué de la FSA, de nanoplaquettes d‘HDL et de billes de polysaccharide, ce dernier jouant le rôle de matrice macrostructurante. De façon notable, le taux d‘encapsulation de l‘enzyme dans la matrice macroscopique est amélioré lorsque le biocatalyseur est pré-encapsulé dans les nanoplaquettes d‘HDL. Ceci est attribué aux interactions électrostatiques favorables entre les chaînes de polysaccharide et les HDL, facilitant une charge de matière plus importante. L‘efficacité catalytique du bioréacteur obtenu et sa recyclabilité ont été démontrés. Dans la troisième partie de cette thèse, nous décrivons pour la première fois la conception de bionanoréacteurs enzymes@HDL par co-immobilisation de systèmes bi- ou tétra-enzymatiques dans les HDL permettant de réaliser des cascades multienzymatiques biomimétiques. L‘immobilisation des différentes enzymes prises séparément a d‘abord été optimisée afin de déterminer les conditions de co-immobilisation et de réaliser les cascades biocatalytiques en phase hétérogène. Ces bionanoréacteurs, dont nous avons démontré la recyclabilité, ont été appliqués pour la synthèse de sucres phosphorylés de série D. Enfin, une cascade multienzymatique a été conçue de novo en solution aqueuse et optimisée pour synthétiser différents sucres phosphorylés rares de série L. / 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.