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This thesis focuses on developing a new photocoupling surface, base on polyallyamine (PAAm), to increase the efficiency of the photocoupling agent perfluorophenyl azide (PFPA) in the immobilization of nanoparticles, carbohydrates and graphene. Extensive studies have been carried out in our lab on the covalent immobilization of polymers and graphene using PFPA-functionalized surfaces. Here we show that PAAm-based PFPA surface can be used to efficiently immobilize not only graphene and polymers but also nanomaterials and small molecules. This was accomplished by first silanizing silicon wafers with PFPA-silane followed by attaching a thin film of PAAm by UV radiation. Treating the PAAm surface with N-hydroxysuccinimide-derivatized PFPA (PFPA-NHS) yielded the PAAm-PFPA surface. The functionalized surfaces were characterized by ellipsometry (layer thickness), contact angle (surface tension), and ATR-FTIR. The PAAm surface was further characterized by determining the density of amino groups on the surface. The PAAm-PFPA surfaces were subsequently used to covalently immobilize polymers, nanomaterials, carbohydrates and graphene by a simple procedure of coating the molecules or materials on the PAAm-PFPA surface followed by UV irradiation. The resulting surfaces were characterized using ellipsometry, AFM, optical microscopy. The attached carbohydrates were further evaluated using lectins, i.e., carbohydrate-binding proteins.

ABSTRACT Covalent Immobilization of Glucose Isomerase on Poly (2-hydroxyethyl methacrylate) Particles Yildiz, Hakan &Uuml / mit M.S., Department of Chemistry Supervisor: Prof. Dr. Nesrin Hasirci July 2004, 54 pages In this study, poly (2-hydroxyethyl methacrylate), P(HEMA), particles were prepared by suspension polymerization of the monomer 2-hydroxyethyl methacrylate with addition of ethylene glycol dimethyacrylate, EGDMA, as cross linker. Glucose isomerase, GI, enzyme was covalently immobilized on the prepared P(HEMA) particles after activation of the particles with cyanuric chloride. The activities of the free and immobilized enzymes were measured with Ethanol-Carbazole method. The immobilization of GI on P(HEMA) particles promoted enzyme stability and as a result, the enzyme became more stable to temperature, storage, and reuse. For maximum substrate conversion, optimum temperature was determined as 70 oC for free GI and this value shifted to 60 oC for immobilized enzyme. Optimum pH for maximum substrate conversion was found to be 7.0 for free GI and 8.0 for immobilized GI. The change of enzyme activity with substrate concentration were determined to calculate Km and Vmax values of the free and immobilized enzymes. Km values were found to be 1.7x10-2 mol/L and 3.1x10-1 mol/L while Vmax values were 1.01x10-4 mol/L.min, 1.65x10-3 mol/L.min for free and immobilized GI, respectively. Reuse capability of immobilized GI on P(HEMA) particles was measured and compared with commercial GI. Both systems retained 80 % of their original activities after 40th use, within 6 days. The change of enzyme activities upon storage were detected at certain time intervals for the samples stored in buffer solution at 4 oC. Immobilized enzyme was retained 60% of its original activitiy in 60 days of storage at 4 oC. Immobilized GI and commercial GI both retained 90% of their activities under continuous flow after 180 mL of substrate solution passed through the column.

Tesis por compendio / [ES] En la presente tesis doctoral se ha evaluado el uso de nuevos soportes celulósicos y silíceos como sistemas de filtración para la estabilización y conservación de alimentos líquidos con el fin de afrontar dos grandes retos de la industria de bebidas. Por un lado, evitar o minimizar los cambios en las propiedades nutricionales, estructurales y organolépticas de los alimentos, ocasionados por la pasteurización térmica tradicional, y ofrecer una alternativa al problema de la baja viabilidad debida a los altos costos de inversión/producción al aplicar nuevas tecnologías no térmicas. Por ello, esta tesis doctoral se centra en el desarrollo y evaluación de una nueva tecnología no térmica de conservación de alimentos líquidos basada en la filtración. Se han desarrollado sistemas de filtración a partir de soportes celulósicos y silíceos, sin funcionalizar o funcionalizados con compuestos antimicrobianos. En el primer capítulo se evaluó el uso de materiales de celulosa como soportes filtrantes para el tratamiento de alimentos líquidos. Como primera aproximación se desarrolló un material poroso nano-micro tubular a partir de la extracción y deslignificación del material celulósico presente en el corazón o raquis de la mazorca de maíz. El uso de este soporte resultó ser efectivo como material filtrante para el tratamiento de agua y zumo de naranja, en un sistema de flujo continuo, eliminando la carga microbiana. La aplicación de este soporte como sistema de filtración presenta diversas ventajas como su capacidad de retención microbiana, la reutilización de sub-productos del maíz y, por tanto, su respeto al medioambiente. Sin embargo, sería necesario optimizar el proceso de filtrado para evitar la frecuente obturación de sus poros que requirió varios ciclos de lavado durante el proceso, así como establecer un método de regeneración del material para incrementar su vida útil. Además, este sistema afectó al color del zumo filtrado, que no se mantuvo constante durante el proceso, lo que supone una importante desventaja que es necesaria abordar. Como segunda aproximación, se evaluó el potencial de la inmovilización de una molécula bioactiva sobre membranas de celulosa, para mejorar la capacidad de retención microbiana del material celulósico, así como permitir su reutilización. Los filtros de celulosa funcionalizados con poliaminas demostraron ser eficaces en la eliminación de patógenos en agua, debido a las cargas positivas generadas por los grupos amina inmovilizados en la superficie de las membranas, que atraen y retienen las bacterias cargadas negativamente. Dada la fácil preparación y procedimiento de uso de las membranas de celulosa funcionalizadas con poliaminas, éstas podrían ser consideradas una buena opción para el desarrollo de sistemas de tratamiento de aguas in situ, rápidos, de fácil manejo y de bajo coste. El segundo capítulo describe el desarrollo y aplicación de partículas de sílice funcionalizadas con compuestos de aceites esenciales, con el fin de diseñar coadyuvantes de filtración con actividad antimicrobiana. La filtración de diversas matrices alimentarias (agua, cerveza y zumo de manzana) a través de los soportes funcionalizados con los antimicrobianos naturales demostró ser eficaz en la reducción del recuento de la cepa patógena Escherichia coli, así como frente a la microflora endógena de la cerveza y el zumo (bacterias acidolácticas, aerobios mesófilos, psicrófilos, mohos y levaduras). La eficacia en el control microbiano se debe a la combinación de la adsorción física y la inactivación por contacto con los compuestos de aceites esenciales inmovilizados. Además, la evaluación de las propiedades físico-químicas y sensoriales de los alimentos líquidos demostró un efecto poco significativo, éste depende del tamaño de las partículas de sílice usadas y de la molécula bioactiva inmovilizada. Por lo tanto, el sistema de conservaci� / [CA] En la present tesi doctoral s'ha avaluat l'ús de nous suports cel·lulòsics i silicis com a sistemes de filtració per a l'estabilització i conservació d'aliments líquids, amb la finalitat d'afrontar dos grans reptes de la indústria de begudes. D'una banda, evitar o minimitzar els canvis en les propietats nutricionals, estructurals i organolèptiques dels aliments, ocasionats per la pasteurització tèrmica tradicional, i oferir una alternativa al problema de la baixa viabilitat deguda als alts costos d'inversió/producció en aplicar noves tecnologies no tèrmiques. Per això, aquesta tesi doctoral es centra en el desenvolupament i avaluació d'una nova tecnologia no tèrmica de conservació d'aliments líquids basada en la filtració. S'han desenvolupat sistemes de filtració a partir de suports cel·lulòsics i silicis, sense funcionalitzar o funcionalitzats amb compostos antimicrobians. En el primer capítol es va avaluar l'ús de materials de cel·lulosa com a suports filtrants per al tractament d'aliments líquids. Com a primera aproximació es va desenvolupar un material porós nano-micro tubular a partir de l'extracció i deslignificació del material cel·lulòsic present en el cor o raquis de la panolla de dacsa. L'ús d'aquest suport va resultar ser efectiu com a material filtrant per al tractament d'aigua i suc de taronja, en un sistema de flux continu, eliminant la càrrega microbiana. L'aplicació d'aquest suport com a sistema de filtració presenta diversos avantatges com la seua capacitat de retenció microbiana, la reutilització de subproductes de la dacsa i, per tant, el seu respecte al medi ambient. No obstant això, seria necessari optimitzar el procés de filtrat per a evitar la freqüent obturació dels seus porus que va requerir diversos cicles de rentada durant el procés, així com establir un mètode de regeneració del material per a incrementar la seua vida útil. A més, aquest sistema va afectar el color del suc filtrat, que no es va mantenir constant durant el procés, la qual cosa suposa un important desavantatge que és necessari abordar. Com a segona aproximació, es va avaluar el potencial de la immobilització d'una molècula bioactiva sobre membranes de cel·lulosa, per a millorar la capacitat de retenció microbiana del material cel·lulòsic, així com permetre la seua reutilització. Els filtres de cel·lulosa funcionalitzats amb poliamines van demostrar ser eficaces en l'eliminació de patògens en aigua, a causa de les càrregues positives generades pels grups amina immobilitzats en la superfície de les membranes, que atrauen i retenen els bacteris carregats negativament. Donada la fàcil preparació i procediment d'ús de les membranes de cel·lulosa funcionalitzades amb poliamines, aquestes podrien ser considerades una bona opció per al desenvolupament de sistemes de tractament d'aigües in situ, ràpids, de fàcil maneig i de baix cost. El segon capítol descriu el desenvolupament i aplicació de partícules de sílice funcionalitzades amb compostos d'olis essencials, amb la finalitat de dissenyar coadjuvants de filtració amb activitat antimicrobiana. La filtració de diverses matrius alimentàries (aigua, cervesa i suc de poma) a través dels suports funcionalitzats amb els antimicrobians naturals va demostrar ser eficaç en la reducció del recompte del cep patogen Escherichia coli, així com enfront de la microflora endògena de la cervesa i el suc (bacteris àcid làctics, aerobis mesòfils, psicròfils, floridures i llevats). L'eficàcia en el control microbià es deu a la combinació de l'adsorció física i la inactivació per contacte amb els compostos d'olis essencials immobilitzats. A més, l'avaluació de les propietats fisicoquímiques i sensorials dels aliments líquids estudiats va demostrar un efecte poc significatiu, aquest depèn de la grandària de les partícules de sílice usades i de la molècula bioactiva immobilitzada. Per tant, el sistema de conserv / [EN] In the present doctoral thesis the use of new cellulosic and silica supports as filtering systems for the stabilization and preservation of liquid foods has been evaluated to overcome two major challenges of the beverage industry. On the one hand, avoid or minimize the changes in the nutritional, structural and organoleptic properties of food caused by traditional thermal pasteurization, and offer an alternative to the problem of low viability due to high investment/production costs when applying new non-thermal technologies. Therefore, this doctoral thesis focuses on the development and evaluation of a new non-thermal technology for the preservation of liquid foods based on filtration. The filtering systems have been developed from cellulosic and silica supports, non-modified or functionalized with antimicrobial compounds. In the first chapter, the use of cellulose materials as filtering supports for the treatment of liquid foods was evaluated. As first approximation, a porous nano-micro tubular material was developed from the extraction and delignification of the cellulosic material present in the corn stalk. The use of this support was effective as filtering material for the treatment of water and orange juice, in a continuous flow system, eliminating the microbial load. The application of this support as filtering system has several advantages, such as its microbial retention capacity, the reuse of corn by-products and, therefore, its respect for the environment. However, it would be necessary to optimize the filtering process to avoid the frequent clogging of its pores that required several washing cycles during the process, as well as to establish a method of material regeneration to increase its life. In addition, this system affected the color of the filtered juice, which did not remain constant during the process, representing an important disadvantage that must be addressed. As a second approach, the potential of the immobilization of a bioactive molecule on cellulose membranes was evaluated to improve the microbial retention capacity of the cellulosic material, as well as to allow its reuse. The cellulose filters functionalized with polyamines proved to be effective in eliminating pathogens in water, due to the positive charges generated by the amine groups immobilized on the surface of the membranes, which attract and retain the negatively charged bacteria. Given the easy preparation and usage of the polyamines-functionalized cellulose membranes, these could be considered a good option for the development of fast, easy to use and low cost in situ water treatment systems. The second chapter describes the development and application of silica particles functionalized with essential oil components to design filtering aids with antimicrobial activity. The filtration of various food matrices (water, beer and apple juice) through the supports functionalized with natural antimicrobials proved to be effective in reducing the load of the pathogenic strain Escherichia coli, as well as reducing the endogenous microflora of beer and the juice (lactic acid bacteria, mesophilic, psychrophilic, mold and yeast). The removal capability is due to the combination of physical adsorption and contact inactivation with the essential oil compounds immobilized. In addition, the evaluation of the physicochemical and sensory properties of the liquid foods studied showed a not significant effect, it depends on the size of the silica particles used and the immobilized bioactive molecule. Therefore, the proposed preservation system has a high potential for cold beverage pasteurization processes. / N. Peña-Gomez would like to thank for financial support in the frame of her PhD project to Operational Programme of the European Social Fund (ESF) 2014-2020, the Agencia Estatal de Investigación, Generalitat Valenciana and FEDER-EU (Projects RTI2018-101599-B-C21 and AGL2015-70235-C2-1-R). The authors also thank the Electronic Microscopy & Microanalysis Laboratory at Patras University for support. / Peña Gomez, N. (2020). Development of polymeric and silica filtering materials functionalized with antimicrobial compounds for the elimination of microorganisms in liquid food [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/137041 / Compendio

Le but de ce travail a été d’élaborer des nanoparticules magnétiques (MNPs) fonctionnalisées avec un groupement maléimide, stables, dispersibles dans l’eau et qui assureront une immobilisation covalente,sélective et efficace de biomolécules. Bien qu’un large choix de MNPs soit disponible dans le commerce, lamodification chimique de surface des MNPs reste une étape indispensable pour l’élaboration de matériauxspécifiques. Un contrôle précis de la fonctionnalisation de surface des MNPs est crucial, car en découlentleurs propriétés physico-chimiques, leur stabilité colloïdale, et la préservation de l’activité biologique de labiomolécule immobilisée. Dans ce travail, nous proposons d’augmenter le nombre de groupes fonctionnels(maléimide) accessibles à la surface de MNPs, en la modifiant par des agents de couplage dendritiques. Deuxtypes de MNPs coeur-écorce de 300 nm (avec un noyau de γ-Fe2O3 et une écorce de polymère ou de silice)ont été utilisés. Afin d’étudier l’effet «dendritique» sur la fonctionnalisation de surface, trois types d’agentsde couplage ont été conçus: des agents de couplage linéaires (contenant un groupe maléimide), des agents decouplage dendritiques à deux branches (contenant deux groupes maléimide) et des agents de couplagedendritiques à quatre branches (contenant quatre groupes maléimide). L’efficacité de ces MNPsfonctionnalisées pour immobiliser des biomolécules ou des modèles de biomolécules a été étudiée. Cetteétude a démontré l’intérêt de la fonctionnalisation de la surface des MNPs coeur-écorce par des structuresdendritiques pour une immobilisation efficace et spécifique de biomolécules. / The purpose of this work is to design stable, water-dispersible, maleimide functionalized magneticnanoparticles (MNPs) that will ensure selective covalent immobilization of biomolecules. While, a largechoice of MNPs is now commercially available, the surface modification of MNPs remains an indispensablestep in the elaboration of such MNPs. A precise control over the surface functionalization of MNPs iscrucial, because it governs their physicochemical properties, their colloidal stability, and their biologicalbehaviour. In this work with the aim to increase the number of functional groups on MNPs’ surfaces, it wasproposed to functionalize MNPs with dendritic coupling agents and to compare their efficiency with thosefunctionalized with a linear analogue. Moreover, it was decided to investigate the “dendritic effect” of thesurface functionalization on two types of core-shell MNPs (300 nm) that consist of a maghemite (γ-Fe2O3)ferrofluid core coated with: (I) polymer shell or (II) silica shell. Therefore, three types of coupling agents(that possess an amino or silane anchoring site) were synthesized: linear coupling agents (containing onemaleimide functional group); two-branched coupling agents (containing two maleimide functional groups)and four-branched dendritic coupling agents (containing four maleimide functional groups). Then, thecapacity of MNPs functionalized with dendritic or linear coupling agents to immobilize biomolecules ormodels of biomolecules was investigated. This study proved the efficiency of the surface functionalizationwith dendritic structures for the immobilization of biomolecules.

<p>The work described in this thesis aims to achieving surface patterning through chemical activation of thiolated silicon oxide surfaces, resulting in a spatially controlled covalent immobilization of biomolecules with high resolution.</p><p>Existing chemical methods to immobilize molecules on surfaces do not reach below the micrometer scale while the ones allowing for spatial control mostly lead to non-covalent adsorption of molecules on surfaces, or require several successive chemical reactions to obtain the final covalent immobilization. Methods with improved chemical processes and novel surface modification techniques had to be developed. </p><p>A basic need for studying interactions of biomolecules on chemically modified surfaces with high resolution is the ability to obtain a simple, inexpensive method resulting in ultraflat densely packed and reproducible organic monolayers. Therefore, a new method for silicon oxide chemical derivatization, fulfilling these requirements, was developed. </p><p>Thiol derivatized silicon oxide surfaces allow for a diversity of activation reactions to occur, resulting in thiol-disulfide exchange. The electrooxidation of surface-bound thiol groups was investigated as a way of generating reactive thiolsulfinates/thiolsulfonates, by application of a positive potential difference to the silicon surfaces. Peptide molecules containing thiol groups were successfully immobilized to the electroactivated surfaces. In addition, this new chemical activation method offers the possibility to release the bound molecules in order to regenerate the surfaces. Subsequently, the thiolated surfaces can be reactivated for further use.</p><p>Since the activated area depends directly on the size of the electrodes used for the oxidation, nanoscale activation of the thiolated surfaces was performed by use of an AFM tip as counter-electrode. Electrooxidized patterns, with a line width ranging from 70 nm to 200 nm, were obtained. A thiol-rich protein, b-galactosidase, was selectively immobilized onto the electroactivated patterns.</p><p>An electrochemical version of microcontact printing was developed in order to activate large surface areas with micrometer scale patterns. Conductive soft polymer stamps were produced using an evaporated aluminum coating. Patterned electroactivation of thiols was achieved, and polystyrene beads were subsequently specifically immobilized onto the patterns.</p><p>As a conclusion, these different projects resulted in a strategy enabling the achievement of nanoscale and microscale positioning and immobilization of biomolecules on silicon surfaces, with potential reversibility and reuse of the surfaces.</p>

The work described in this thesis aims to achieving surface patterning through chemical activation of thiolated silicon oxide surfaces, resulting in a spatially controlled covalent immobilization of biomolecules with high resolution. Existing chemical methods to immobilize molecules on surfaces do not reach below the micrometer scale while the ones allowing for spatial control mostly lead to non-covalent adsorption of molecules on surfaces, or require several successive chemical reactions to obtain the final covalent immobilization. Methods with improved chemical processes and novel surface modification techniques had to be developed. A basic need for studying interactions of biomolecules on chemically modified surfaces with high resolution is the ability to obtain a simple, inexpensive method resulting in ultraflat densely packed and reproducible organic monolayers. Therefore, a new method for silicon oxide chemical derivatization, fulfilling these requirements, was developed. Thiol derivatized silicon oxide surfaces allow for a diversity of activation reactions to occur, resulting in thiol-disulfide exchange. The electrooxidation of surface-bound thiol groups was investigated as a way of generating reactive thiolsulfinates/thiolsulfonates, by application of a positive potential difference to the silicon surfaces. Peptide molecules containing thiol groups were successfully immobilized to the electroactivated surfaces. In addition, this new chemical activation method offers the possibility to release the bound molecules in order to regenerate the surfaces. Subsequently, the thiolated surfaces can be reactivated for further use. Since the activated area depends directly on the size of the electrodes used for the oxidation, nanoscale activation of the thiolated surfaces was performed by use of an AFM tip as counter-electrode. Electrooxidized patterns, with a line width ranging from 70 nm to 200 nm, were obtained. A thiol-rich protein, b-galactosidase, was selectively immobilized onto the electroactivated patterns. An electrochemical version of microcontact printing was developed in order to activate large surface areas with micrometer scale patterns. Conductive soft polymer stamps were produced using an evaporated aluminum coating. Patterned electroactivation of thiols was achieved, and polystyrene beads were subsequently specifically immobilized onto the patterns. As a conclusion, these different projects resulted in a strategy enabling the achievement of nanoscale and microscale positioning and immobilization of biomolecules on silicon surfaces, with potential reversibility and reuse of the surfaces.

Amine transaminases (ATA) catalyse the transfer of an amino group from one molecule and replaces a ketone or aldehyde with the amino group, the amino group on the amino-donor is replaced with a ketone or aldehyde. This enzyme, ATA from Chromobacterium violaceum, has previously been used to catalyse the reaction involving amphetamine, therefore, it might be possible to use this enzyme to convert amphetamine and the product absorbs in the UV spectrum and can therefore be measured spectrophotometrically. The aim of the project was to explore the possibility of using ATA in a portable biosensor for the detection of amphetamine. A literature study of commercially available portable biosensors was performed, activity of the free enzyme was tested against two substrates, methylbenzylamine (MBA) and amphetamine. Research on immobilization techniques, materials, and surface functionalization was done to chose suitable methods for immobilizing ATA. Two immobilization methods were suggested and one of the methods, ionic immobilization through His-tag towards Ni2+ on the surface, was tested for enzyme activity toward MBA. The enzyme activity of the free enzyme in solution towards MBA was comparable to previously reported enzyme activity, however, no enzyme activity towards amphetamine was observed. No activity was observed for the immobilized enzyme, but it might be due to the experimental design, more experiments need to be performed to draw conclusions. / Amintransaminaser (ATA) katalyserar överförandet av en amingrupp från en molekyl och ersätter en keton eller aldehyd med den amingruppen, amingruppen på amin-donatorn ersätts med en keton eller aldehyd. Det här enzymet, ATA från Chromobacterium violaceum (CvATA), har tidigare använts för att katalysera en reaktion som involverar amfetamin, därför skulle detta enzym kunna användas på amfetamin. Produkten av reaktionen absorberar i UV spektrumet och kan mätas med en spektrofotometer. Målet med projektet var att utforska möjligheten av att använda CvATA i en biosensor för att detektera amfetamin. En litteraturstudie på kommersiellt tillgängliga bärbara biosensorer genomfördes, aktiviteten av det fria enzymet testades mot två substrat, metylbenzylamin (MBA) och amfetamin. Information samlades om immobiliseringstekniker, material, och ytfunktionalisering gjordes för att välja ut lämpliga metoder för immobilisering av CvATA. Två immobiliseringsmetoder föreslogs och en av metoderna, immobilisering via enzymets His6-tagg och Ni2+ joner på ytan, testades för enzymaktivitet mot MBA. Enzymaktiviteten av det fria enzymet i lösning mot MBA var i samma storleksordning som tidigare rapporterad enzymaktivitet, men ingen enzymaktivitet mot amfetamin kunde observeras. Ingen aktivitet kunde observeras för det immobiliserade enzymet, men det kan vara på grund av designen på experimentet, fler experiment behöver göras för att kunna dra några fler slutsatser.

Suite à la première thèse sur le greffage et l’adsorption physique successives de sélecteurs chiraux dans des tubes ouverts en électrochromatographie capillaire (ECC ou CEC) chirale, menée par le Dr Guillaume Pédéhontaa-Hiaa au sein de l’équipe du laboratoire COBRA (IUT d’Evreux), nous avons développé des phases stationnaires chirales covalentes (CSPs) à base de cyclodextrines (CDs) en tubes ouverts et des CSPs sur supports monolithiques pour l’emploi en CEC. Nous avons ainsi évalué les paramètres électrochromatographiques et la stabilité de ces CSPs en séparant une variété de racémiques neutres et chargés. L’influence de la température d’analyse, le potentiel appliqué ainsi que la nature et le pH des électrolytes sur la qualité des électrochromatogrammes ont été étudié en CEC chirale. Cette étude se divise en deux grandes parties. La première concerne les CSPs élaborées sur colonnes à tubes ouverts pour l’OT-CEC. Il s’agit initialement de graver la surface interne d’un capillaire de silice de 50 μm de diamètre interne à l’aide d’une solution de bifluorure d’ammonium dans le but premier d’augmenter considérablement sa surface spécifique et d’immobiliser en surface une grande quantité de sélecteurs chiraux à base de β-CD. Nous avons alors décrit des greffages covalents de CDs anioniques (Scc-β-CD et CM-β-CD) et d’un polymère anionique de CDs (p-CM-β-CD-) en surface de capillaire de gel de silice gravée et modifiée chimiquement par l’aminopropyltriéthoxysilane (APTEOS). Les greffages des sélecteurs ont été reproduits dans les mêmes conditions que dans la thèse rapportée précédemment en électrophorèse. L’originalité de la construction de ces CSPs réside dans la rapidité et la simplicité du couplage dit péptidique à température ambiante, des sélecteurs carboxylés sur des colonnes préalablement gravées. Ce greffage nécessite des agents de couplage peptidique solubles dans l’eau tels que 1-Ethyl-3-(diméthylaminopropyl)carbodiimide (EDC) et le N-Hydroxysuccinimide (NHS). Il peut aussi être obtenu de manière moins efficace avec d’autres agents solubles en milieu organique tels que le O-(Benzotriazol-1-yl)-N,N,N’,N’-tétraméthyluronium tétrafluoroborate et la triéthylamine (TBTU/TEA). Chaque étape menant aux CSPs a été caractérisée par une étude de flux électroosmotique (FEO) en OT-CEC. Des analyses en AFM et en MEB nous renseignent d’avantage sur le succès du procédé « etching » de nos capillaires. La deuxième grande partie de cette étude traite de la synthèse in-situ de CSPs sur des colonnes de type polymères monolithes organiques et un monolithe hybride à base de sol gel. Des post modifications de surface de ces supports monolithiques nous ont permis d’immobiliser de façon covalente et non covalente des sélecteurs de β-CD en surface des volumes macroporeux. Deux collaborations ont vu le jour pour atteindre ces objectifs. La première eut lieu avec le Dr Thuy Tran et le Pr Myriam Taverna de la Faculté de Pharmacie de Chatenay Malabry (UMR 8612), durant laquelle nous avons reproduit une colonne monolithe organique de type méthacrylate, porteuse de groupements phosphate dans l’optique d’adsorber physiquement en surface le polymère cationique de CDs (p-CD+) que nous a transféré le Pr Benjamin Carbonnier et d’évaluer les capacités de discrimination chirale de cette nouvelle CSP en m-CEC. La seconde collaboration a eu lieu avec le Dr Mohamed Guerrouache et le Pr Benjamin Carbonnier au sein du laboratoire ICMPE de Thiais, où nous avons synthétisé des colonnes monolithiques organiques à base d’acrylates dans le but de greffer en surface de façon covalente et non covalente les CDs et polymères de CDs et d’évaluer ces nouvelles CSPs en m-CEC. La troisième phase stationnaire monolithique employée est celle décrite par le Dr Huihui Yang qui décrit un monolithe hybride porteur de groupements sulfonates nous permettant par la suite d’immobiliser électrostatiquement le p-CD+ sur le réseau poreux et d’évaluer cette nouvelle CSP en m-CEC. / New chiral stationary phases have been prepared for Open Tubular and monolithic columns used in electrochromatography capillary. In order to separate racemic mixtures such as flavonoïd, Hidantoïn derivatives, Binaphtalene-2, 2-hydrogenophosphate and others chiral solutes, we use the β-cyclodextrin forms as chiral selector. Besides, β-cyclodextrin seems to be the most efficient chiral selector in chromatography since it is able to complex and dissolve optical organic isomers in an aqueous media, this chiral selector is able to dissolve even lipophilic molecule with high weight. The complexation is based on interactions with β-cyclodextrin. This study aims to elaborate new chiral stationary phase for CEC using β-cyclodextrin polymers and β-cyclodextrin derivatives. Two approaches were used: Firstly, covalent stationary phases coating with carboxymethyl-β-cyclodextrin polymers and oligomers containing carboxyl’s group had been experimented for open tubular and monolithic column in CEC. Then a non-covalent coating cationic polymer of β-cyclodextrin’s derivatives was immobilized (polytrimethyl ammonium β-CD) on continuous organic monoliths bearing anionic’s group. Prior to the covalent coating of the CD’s chiral selector for OT-CEC and m-CEC, we needed to modify the silicate surface and the monolithic surface with a primary amine silicate1,2 (aminopropyltriethoxysilane) and EDA, an amino-organic moiety (Ethylene diamine). The stability of the bonded organic moiety (APTEOS, EDA) were studied by CEC at different pH with constant ionic strength’s buffer. In this way, graft of carboxymethyl-β-cyclodextrin polymer on silica inner surface modified by APTEOS and on NAS-co-EDMA surface modified by EDA succeeded in activating and covalently coupling reagent as EDC and NHS (1-ethyl-3(-3-dimethtylaminopropyl) carbodiimide and N-hydroxysuccinimide, respectively3) with carboxymethyl’s group of carboxymethyl-β-cyclodextrin . The resultant stationary phase lead to stable chiral stationary phases, easier to prepare starting by coupling the selector to the amine’s group using EDC and NHS. In order to optimize enantio-separations by increasing the specific surface of open tubular columns, we reproduce the etching process to bared capillaries with ammonium bifluoride solution, referred to Pesek’s process4. By this mean, we increase dramatically the specific surface of bared capillaries before anchoring CDs polymers to silicate surfaces modified by APTEOS. Finally due to etching process, we obtain a covalent bonded Chiral Stationary Phase (CSP) which led to more efficient and resolvent enantio-separations by CEC. To describe, in another way, the non-covalent coating of CSP, we immobilised a cationic polymer (polytrimethyl ammonium β-CD+) on two kind of continuous organic and silica hybrid monoliths bearing sulfonate5 and phosphate’s groups. Based on precedent results for OT-CEC enantio-separation with LbL stationary phase7, using successive layers charged polymers to separate racemic mixture in CEC, we decided to adsorb a polycationic polymer hydrosoluble onto the silica hybrid monolith column to form chiral stationary phase (CSP) polytrimethyl ammonium β-cyclodextrin. This way of modification for monolithic surface by chiral selectors is nowadays highly efficient and attractive for CEC. The effect of the matrix and the coating’s nature are discussed by comparing the chromatographic parameters.

Made available in DSpace on 2014-12-17T15:42:15Z (GMT). No. of bitstreams: 1 FabioPF_TESE.pdf: 3376603 bytes, checksum: 15dfaa7fe12ca918fd7e1b98c4378dd9 (MD5) Previous issue date: 2011-09-16 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Enzymatic synthesis of peptides using proteases has attracted a great deal of attention in recent years. One key challenge in peptide synthesis is to find supports for protease immobilization capable of working in aqueous medium at high performance, producing watersoluble oligopeptides. At present, few reports have been described using this strategy. Therefore, the aim of this thesis was to immobilize proteases applying different methods (Immobilization by covalent bound, entrapment onto polymeric gels of PVA and immobilization on glycidil metacrylate magnetic nanoparticles) in order to produce water-soluble oligopeptides derived from lysine. Three different proteases were used: trypsin, &#945;-chymotrypsin and bromelain. According to immobilization strategies associated to the type of protease employed, trypsin-resin systems showed the best performance in terms of hydrolytic activity and oligopeptides synthesis. Hydrolytic activities of the free and immobilized enzymes were determined spectrophotometrically based on the absorbance change at 660 nm at 25 ?C (Casein method). Calculations of oligolysine yield and average degree of polymerization (DPavg) were monitored by 1H-NMR analysis. Trypsin was covalently immobilized onto four different resins (Amberzyme, Eupergit C, Eupergit CM and Grace 192). Maximum yield of bound protein was 92 mg/g, 82 mg/g and 60 mg/g support for each resin respectively. The effectiveness of these systems (Trypsin-resins) was evaluated by hydrolysis of casein and synthesis of water-soluble oligolysine. Most systems were capable of catalyzing oligopeptide synthesis in aqueous medium, albeit at different efficiencies, namely: 40, 37 and 35% for Amberzyme, Eupergit C and Eupergit CM, respectively, in comparison with free enzyme. These systems produced oligomers in only 1 hour with DPavg higher than free enzyme. Among these systems, the Eupergit C-Trypsin system showed greater efficiency than others in terms of hydrolytic activity and thermal stability. However, this did not occur for oligolysine synthesis. Trypsin-Amberzyme proved to be more successful in oligopeptide synthesis, and exhibited excellent reusability, since it retained 90% of its initial hydrolytic and synthetic activity after 7 reuses. Trypsin hydrophobic interactions with Amberzyme support are responsible for protecting against strong enzyme conformational changes in the medium. In addition, the high concentration of oxirane groups on the surface promoted multi-covalent linking and, consequently, prevented the immobilized enzyme from leaching. The aforementioned results suggest that immobilized Trypsin on the supports evaluated can be efficiently used for oligopeptides synthesis in aqueous media / S?ntese enzim?tica de pept?deos usando proteases tem atra?do uma enorme aten??o nos ?ltimos anos. Um desafio chave na s?ntese de pept?deos ? encontrar suportes para imobiliza??o de proteases capazes de apresentar um alto desempenho em meio aquoso, produzindo oligopept?deos sol?veis em ?gua, j? que at? o presente momento, pouco tem sido descrito usando essa estrat?gia. Dessa forma, o objetivo dessa tese foi imobilizar proteases usando diferentes m?todos (imobiliza??o por liga??o covalente, aprisionamento em g?is polim?ricos de PVA e imobiliza??o em nanopart?culas magn?ticas de Glicidil) para a produ??o de oligopept?deos derivados da lisina. Tr?s proteases foram utilizadas: tripsina, &#945;-quimotripsina e bromela?na. De acordo com as estrat?gias de imobiliza??o associadas ao tipo de protease empregada, foi provado que os sistemas tripsina-resinas mostraram os melhores desempenhos em termos de atividade hidrol?tica e s?ntese de oligopept?deos. A atividade hidrol?tica das enzimas livres e imobilizadas foi determinada por espectrofotometria com base na mudan?a de absorb?ncia em 660 nm ? temperatura de 25 ?C (Casein method). O rendimento de oligolisina e o c?lculo do grau de polimeriza??o m?dio foram monitorados por RMN H. A protease tripsina foi covalentemente imobilizada em quatro diferentes resinas (Amberzyme, Eupergit C, Eupergit CM and Grace 192). O m?ximo rendimento de prote?na imobilizada foi 92, 82, 60, e 71 mg/g de suporte para cada resina, respectivamente. A efici?ncia desses sistemas (Tripsina-resinas) foi avaliada pela hidr?lise do substrato case?na e a s?ntese de oligolisina em meio aquoso. A maioria dos sistemas foram capazes de catalisar a s?ntese de oligopept?deos, entretanto com diferentes efici?ncias, tais como: 40, 37 e 35% para os suportes Amberzyme, Eupergit C e Eupergit CM, respectivamente, em compara??o com a enzima livre. Esses sistemas produziram olig?meros em somente 1 hora com grau de polimeriza??o m?dio mais alto que a enzima livre. Dentre esses sistemas, Eupergit CTripsina mostrou ser mais eficiente que os outros sistemas em termos de atividade hidrol?tica e estabilidade t?rmica, ao passo que n?o exibiu a mesma efici?ncia como era esperado para a s?ntese de oligolisina. Tripsina-amberzyme provou ser mais eficiente para a s?ntese de oligopept?deos, al?m de exibir um excelente reuso, mantendo 90% de sua atividade hidrol?tica e sint?tica ap?s sete reusos. As intera??es hidrof?bicas da tripsina com o suporte Amberzyme s?o respons?veis por proteger a enzima contra as fortes mudan?as conformacionais no meio reacional. Al?m disso, a alta concentra??o de grupos oxiranos na superf?cie da resina promoveu liga??es covalentes multipontuais e, consequentemente, preveniu a enzima imobilizada do processo de desor??o (Leaching process). Os resultados acima mencionados sugerem que a tripsina imobilizada nesses suportes pode ser eficientemente usada para a s?ntese de oligopept?deos em meio aquoso