Дисертації з теми "Derivati cellulosa"

L’objectif de cette étude est de développer de nouveaux matériaux à base de chitosane, de ses dérivés et de fibres de cellulose, sous la forme de nanofibres ou de feuille de papier. Des échantillons de chitosane purifié ont été utilisées afin de préparer les films nanocomposites transparents à base de chitosane (CH) comme matrice (deux chitosanes avec différentes masses molaires et leurs dérivés solubles dans l'eau) et de cellulose nanofibrillaire (NFC) ou de cellulose bactérienne (BC). Les films obtenus sont très transparents; ils affichent de meilleures propriétés mécaniques que ceux à base de chitosane seul. Une autre démarche a consisté à revêtir des feuilles de papier à base d’E. Globulus avec le chitosane ou deux dérivés de chitosane, l'un fluorescent et l'autre soluble dans l'eau. Tout d'abord, un dérivé du chitosane fluorescent a été déposé couche par couche sur des feuilles de papier et sa distribution,a été évaluée. Les résultats montrent que, que la répartition en surface est très homogène et que la pénétration du chitosane dans les pores du papier cesse après un dépôt de trois couches, au-delà une augmentation de l'ensemble de ses épaisseurs et aptitude filmogène. Ensuite, l'effet du chitosane et de son dérivé soluble dans l'eau sur les propriétés finales des papiers a été étudié. En général, chitosane et le chitosane soluble dans l'eau ont un impact positif sur les propriétés finales des papiers couchés. Finalement, la chitine et le chitosane ont été convertis en polyols visqueux à travers une réaction d'oxypropylation simple , dans le but de valoriser les fractions les moins nobles ou les sous-produits de ces précieuses ressources renouvelables
The purpose of this study was to develop new materials based on chitosan and its derivatives and cellulose, in the form of nanofibres or paper sheet. . Chitosan samples were then used to prepare transparent nanocomposite films based on different chitosan (CH) matrices (two chitosans with different DPs and corresponding water-soluble derivatives) and nanofibrillated cellulose (NFC) and bacterial cellulose (BC). The films obtained were shown to be highly transparent, displayed better mechanical properties than the corresponding unfilled chitosan films and showed increased thermal stability. Another approach involved the coating of E. Globulus based paper sheets with chitosan and two different chitosan derivatives, a fluorescent and a water-soluble derivative, on a pilot-size press machine. First, a fluorescent chitosan derivative was deposited layer-by-layer onto conventional paper sheets and its distribution was assessed. The results showed that the surface distribution was highly homogeneous and the penetration of chitosan within the paper pores ceased after a three-layer deposit, beyond coating only produced an increase in its overall thickness and film-forming aptitude. Then, the effect of chitosan and chitosan quaternization on the final properties of chitosan-coated papers was investigated. In general, both chitosan and water-soluble chitosan coatings had a positive impact on the final properties of the coated papers. Finally, chitin and chitosan were converted into viscous polyols through a simple oxypropylation reaction, with the aim of valorizing the less noble fractions or by-products of these valuable renewable resources

Como conseqüência do aumento da produção de cana nos últimos anos, ocorreu o aumento da quantidade de resíduos agroindustriais gerados a partir deste processo, sendo os principais a palha e o bagaço da cana-de-açúcar. O potencial de produção desses resíduos representa em média 14% da massa da cana processada. A celulose é o principal constituinte desses materiais e pode dar origem a outros materiais por meio de reações de derivatização. Entre os derivados de celulose mais importantes, estão os éteres e os ésteres de celulose. A celulose também pode ser fragmentada, a fim de se utilizar seu monômero formador, a glicose. O presente trabalho teve como objetivo extrair a celulose da palha e do bagaço de cana para utilizá-la na produção de dois derivados, o acetato de celulose e a carboximetilcelulose, além de fragmentá-la a glicose, visando a estudar a hidrólise enzimática necessária para produção de etanol celulósico. Para isso, foram testadas duas vias de obtenção da celulose, uma via denominada ácida e outra, denominada alcalina. Ao término de cada etapa das vias, os materiais produzidos foram caracterizados quimicamente com a finalidade de se elucidar o que acontecia em cada etapa. Ao final dos dois processos, o material obtido foi submetido às reações de acetilação e de carboximetilação. Os derivados de celulose foram caracterizados quanto aos seus graus de substituição e por FTIR. Com o acetato de celulose, foram produzidas membranas através de dois métodos distintos, a evaporação de solvente e a inversão de fases. Essas membranas foram caracterizadas fisicamente por MEV, DMA e teste de permeabilidade. Elas também foram testadas quanto à remoção de íons cobre em solução em estado estacionário. Todos os materiais obtidos nas duas vias testadas foram hidrolisados enzimaticamente utilizando-se as enzimas Celluclast 1.5L e ?-glicosidase. Em todas as vias estudadas e para os dois materiais analisados, foram obtidos como produtos finais, materiais com alto teor de celulose (em torno de 90%) e baixo de teor de lignina (menor que 4%), sendo a via alcalina considerada a de melhor desempenho, pois ocorreu menor perda de celulose nessa via do que na via ácida. Foram produzidos acetatos de celulose com grau de substituição 3, ou seja, triacetatos, ideais para a produção de membranas. Contudo, a presença da lignina, mesmo em pequena quantidade, não permitiu que fossem produzidas membranas com alta resistência mecânica. Em geral as membranas foram capazes de remover cerca de 15,0% dos íons cobres em uma solução aquosa. Dos dois métodos estudados, o de inversão de fases foi o que produziu as melhores membranas. Quanto à carboximetilcelulose, foram produzidas CMCs de diferentes características e mais uma vez a lignina interferiu no processo, quanto mais lignina possuía o material antes da produção de CMC, menor foi o grau de substituição obtido. Nas reações de hidrólise enzimática, quanto mais puro era o material em relação ao teor de celulose, maior foi a concentração de glicose no hidrolisado, sendo alcançadas concentrações em torno de 85,00%.
As a consequence of sugarcane increased production in recent years, there was an increased of residues generation from this process, being the straw and bagasse the main ones. The production potential of these wastes represents around 14% of the processed sugarcane mass. Cellulose is the main constituent of these materials and may give rise to other materials by derivatization reactions. Among the most important derivatives of cellulose, are ethers and esters of cellulose. Cellulose can also be fragmented in order to use its monomer, the glucose. The present work aims at extracting the cellulose from sugarcane straw and bagasse to use it in the production of two derivatives, cellulose acetate and carboxymethylcellulose and to fragment it into glucose for studying the enzymatic hydrolysis, which is a required step for ethanol cellulosic production. For this, it was tested two pathways of cellulose obtaining, the acid route and the alkaline route. At the end of each stage of the process, the materials were characterized chemically in order to elucidate what occurred in each step. After finishing both processes, the material was subjected to reactions of acetylation and carboxymethylation. The cellulose derivates were characterized physically for its degree of substitution and for FTIR. The cellulose acetate was utilized to produce membranes through two different methods, the solvent evaporation and the phase inversion. The membranes were characterized for MEV, DMA and permeability test. They were also tested for cooper ions removal. All materials produced at both pathways were hydrolyzed enzymatically for the enzymes Celluclast 1.5L and ?-glucosidase. In all cases, the final material presented high level of cellulose (about 90,0%) and low level of lignin (low than 4,0%). The alkaline route can be considered the one which achieved the best results, since it was in this pathway that the lowest cellulose lost occurred. The cellulose acetates presented a degree of substitution 3, in other words, they are triacetates, ideal for membrane production. Nevertheless, the presence of lignin, even in low amount, did not allow producing membranes with high mechanic resistance. In general, the membranes were able to remove about 15,0% of cooper ions in a aqueous solution. Between the methods carried out, the phase inversion was the one which produced membranes with the best properties. In relation to carboxymethylcellulose, it was obtained CMCs with different characteristics and, once more, the lignin interfered in the process. The more lignin content before CMC production, the less degree of substitution obtained. In the reactions of enzymatic hydrolysis, the highest cellulose purity proportioned the highest glucose concentrations in the hidrolysates, and it was reached conversion values around 85,00%.

Membranes, starting from natural to industrial ones, have a fundamental role in many fields as thin barrier with characteristic permeate selectivity. For protection, separation or filtration, the membrane use increased significantly in the past century. In the last years, the possibility to obtain membranes from renewable material started to be a priority. This work focuses on the production of regenerated cellulose membranes, starting from cellulose derivative. The use of this raw material represents an important starting point in the realization of a sustainable product. Regenerated cellulose suits well filtration of aqueous solution, removal of impurities and separation treatments. The advantages of regenerated cellulose use are several: natural origin, available in large quantities, biocompatibility and biodegradability. The aim of this work is to improve an industrial manufacturing process of microfiltration membranes with required features. Particular attention is given to hydrolysis, fundamental step in order to eliminate substituent groups and maintain a stable structure. The raw materials and the competitor samples were characterized in order to realize a precise and detailed starting point for the study. Many variables were taken into consideration: the thickness of the membrane and the possibility of casting supported or not supported films.The effect of polymer concentration in the solution was studied. The influence of the solution formation temperature, the percentage of additive for pores formation and the different coagulation bath composition, have also been analyzed. Several analytical techniques were adopted in order to evaluate the previously described characteristics. The hydrolysis was conducted with a basic solution. The studies carried out have made it possible to identify a timing and a concentration suitable for the complete elimination of the substituent groups and, at the same time, for the maintenance of the membrane stability.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第14668号
農博第1750号
新制||農||968(附属図書館)
学位論文||H21||N4441(農学部図書室)
UT51-2009-D380
京都大学大学院農学研究科森林科学専攻
(主査)教授 西尾 嘉之, 教授 中坪 文明, 教授 木村 恒久
学位規則第4条第1項該当

Neuartige Cellulosederivate werden ausgehend von kommerziellen Celluloseethern synthetisiert. Aufgrund der guten Löslichkeit der Celluloseether in polaren Lösungsmitteln erfolgt eine homogene Reaktionsführung, wodurch eine regelmäßige Verteilung der Sulfatgruppen entlang der Polymerkette gewährleistet wird. Durch Variation der Reaktionsparameter wie Sulfatierungsmittel, Lösungsmittel, Reaktionszeit und -temperatur erfolgte die Synthese zahlreicher Celluloseethersulfate mit unterschiedlichen Eigenschaften bezüglich Sulfatierungsgrad und kinematischer Viskosität. Durch Bestimmung des Schwefelgehaltes und entsprechender Berechnungen konnten die Anzahl der Sulfatgruppen im Molekül (DSSul) ermittelt werden, wobei die Werte für die synthetisierten Proben im Bereich zwischen DSSul = 0.1 bis DSSul = 2.7 lagen. Der Abbau der Polymerkette wurde ebenfalls durch die Reaktionsbedingungen gesteuert, sodass sowohl Produkte mit hohen (1698 mm2/s) als auch sehr niedrigen (2 mm2/s) kinemtischen Viskositäten resultierten. Wasserlöslichkeit der Produkte wurde durch Trübungsmessungen von 1%igen wässrige Lösungen und der daraus erhaltenen geringen Trübungswerte (NTU < 10) ermittelt. Die Funktionalisierung der Celluloseether mit Sulfatgruppen konnte mittels spektroskopischer Methoden nachgewiesen werden. In 13C-NMR-Spektren von Hydroxypropylcellulosesulfaten wurden zusammen-hängende strukturelle Veränderungen mit dem Anstieg des DSSul der Produkte korreliert. Durch charakteristische Signale im Bereich der Ether-Kohlenstoffatome und deren Verschiebung wurde belegt, dass die Sulfatierung des Celluloseethers an den freien Hydroxylgruppen der Etherseitenkette erfolgte. Mittels FT-RAMAN-Spektroskopie konnten für Sulfatgruppen charakteristische Banden der in den Spektren der sulfatierten Celluloseether nachgewiesen und zugeordnet werden. Aufgrund der ionischen Sulfatgruppen dissoziieren die Celluloseethersulfate in Wasser in geladene Polymerketten. Dadurch ist in Gegenwart von kationischen Polyelektrolyten (polyDADMAC) die Bildung von Polyelektrolytkomplexen in Form von Kapseln und Folien/Membranen möglich. Die Fähigkeit solcher Polyelektrolytkapseln aus Celluloseethersulat und polyDADMAC zu Verkapselung von Substanzen und deren anschließende Freisetzung wurde am Beispiel der Verkapselung des Fluoreszenzfarbstoffes Rhodamin B gezeigt. Mittels fluoreszenzspektroskopischer Messungen konnte der aus den Kapseln freiwerdende Farbstoff detektiert werden. Anhand der Messungen wurde gezeigt, dass die Farbstofffreigabe im Fall von Rhodamin B abhängig von den Probeneigenschaften ist. Durch die Wahl des Ausgangsstoffes und deren Funktionalisierung mit Sulfatgruppen kann die Farbstofffreisetzung gesteuert werden. Mit zunehmendem DSSul des Celluloseethersulfates verlängert sich die Verweilzeit des Fluoreszenz-farbstoffes in der Kapsel. Zusätzliche Funktionelle Gruppen in der Seitenkette des Ausgangsstoffes führen zu sterischen Hinderung bei der Wechselwirkung mit polyDADMAC, wodurch eine gegenseitige Durchdringung der Polymerketten bei der Ausbildung des Polyelektrolytkomplexes gehindert wird, sodass weniger kompakte Membranstrukturen der Kapseln resultieren. In Zellexperimente mit adhärenten Zelllinien an entsprechenden mit Celluloseethersulfat präpartierten Oberflächen wurde gezeigt, dass die Zelladhäsion durch den Sulfatierungsgrad der Proben beeinflusst wird. Auf Proben mit höherem Sulfatierungsgrad findet eine verbesserte Adhäsion im Vergleich zu Proben statt, die einen geringen Sulfatierungsgrad aufweisen. Demnach wird die Kompatibilität der Zellen auf solche Oberflächen durch die Erhöhung des Substitutionsgrades der Proben begünstigt.

Les carbones nanostructurés sont très largement utilisés dans les systèmes de stockage et conversion d'énergie par voie électrochimique, par exemple en tant que matériau d'électrode de pile à combustible et de batterie ou encore de supercondensateur. La structure du carbone ainsi que sa chimie de surface sont des paramètres primordiaux et doivent être adaptés aux différentes spécificités de chacune de ces applications. Dans ce cadre général, cette thèse a pour but de développer une nouvelle famille de carbones nanostructurés, les aérogels de carbone cellulosiques. Ces derniers sont obtenus par pyrolyse d'aérogels organiques élaborés à partir d'acétate de cellulose. Pour ce faire, nous avons fait varier les paramètres de synthèse sol-gel ainsi que les conditions de séchage et de pyrolyse (principalement la composition du sol, la nature du catalyseur, la température et l'atmosphère de pyrolyse) afin de générer une vaste palette de structures. Dans un second temps, ces aérogels ont subi différents post-traitements visant à modifier leur chimie de surface et ce, par introduction de groupements fonctionnels oxygénés et azotés. Finalement, les Performances de ces nouveaux aérogels de carbone ont été analysées sous la forme de matériaux d'électrode de supercondensateur
Nanostructured carbons are widely used in electrochemical energy storage and conversion devices, e. G. As electrode material for fuel cells, batteries, or still EDLCs (Electric Double Layer Capacitor). The carbon structure and surface chemistry are crucial parameters and consequently need to be adjusted to the specific application's requirements. This PhD thesis has aimed at developing a new family of nanostructured carbons: aerogels from renewable organic sol-gel precursors, i. E. Pyrolyzed cellulose-acetate-based aerogels. Sol-gel synthesis parameters and drying conditions of the organic gel, as well as pyrolysis parameters (particularly the influence of the sol composition, the type of catalyst used in the sol-gel synthesis step, pyrolysis temperature, and atmosphere) have been varied systematically in order to generate a broad range of structurally different cellulose-acetate-based carbonaceous aerogels. Further, cellulose-acetate-based carbon aerogels have been exposed to different post-treatments (e. G. Introduction of oxygen and nitrogen-containing surface functional groups) to create cellulose-acetate-based carbon aerogels with different surface chemistries. Finally, the performance of these cellulose-acetate-based carbon aerogels has been analyzed as EDLC electrode material

A β-galactosidase (E.C 3.2.1.23) é uma das enzimas mais empregadas na indústria de alimentos sendo utilizada na hidrólise da lactose. Neste trabalho foram utilizadas duas metodologias para imobilização desta enzima. Na primeira delas foi empregado como suporte um material híbrido à base de sílica que possui um grupo orgânico catiônico covalentemente ligado. A adsorção da enzima a este material apresentou eficiência que variou de 74 a 53% com o aumento da quantidade de enzima aplicada ao suporte. A baixa estabilidade térmica da enzima imobilizada obtida e as prováveis fracas interações envolvidas na sua adsorção a este suporte podem explicar o decréscimo de atividade observada durante as sucessivas bateladas de hidrólise da lactose. Na primeira batelada o grau de hidrólise foi de 90,9% e no final da última batelada (4ª), a enzima foi capaz de converter apenas 13% do substrato. A segunda metodologia utilizada foi imobilização covalente da enzima em um filme de celulose/líquido iônico modificado com uma poliamina e ativado com glutaraldeído. A presença da poliamina foi confirmada por análises de infravermelho. Após a imobilização, a enzima reteve 60% de sua atividade inicial. Bons resultados de hidrólise da lactose em batelada foram obtidos tanto a 7ºC como a 35ºC e foi possível reutilizar a enzima imobilizada por 16 ciclos consecutivos, a 7ºC, sem mudanças significativas na atividade enzimática. O valor de Km para a enzima imobilizada no material híbrido à base de sílica foi de 9,17 mM e para a enzima imobilizada nos filmes de celulose foi de 11,22 mM, ambos apresentaram um acréscimo quando comparados ao Km enzima livre (1,25 mM), devido à dificuldade de acesso do substrato ao sítio ativo da enzima. Não houve mudança no pH e temperatura ótimos da enzima imobilizada em relação à enzima livre em nenhum dos métodos testados.
β-galactosidase (E.C 3.2.1.23) is the most widely used enzymes in the food industry and its employed in the lactose hydrolysis process. In this study, two methodologies were used to test their immobilization. In the first, the enzyme was immobilized by adsorption in one silica based hybrid material that contains a cationic organic group covalently linked. The efficiency of immobilization showed a decrease of 74 to 53% by increasing the protein load applied to the support. The low thermo stability of the immobilized enzyme and the probable weak interactions involved in their adsorption, could explain the decrease in enzyme activity observed in the successive batch hydrolysis of lactose. In the first run, the degree of lactose hydrolysis was 90.9% and, at the end of the last run (4th), the enzyme was able to convert only 13% of the substrate. The second methodology used was the covalent immobilization of the enzyme on a cellulose/ionic liquid film, modified with a polyamine and activated using glutaraldehyde. The presence of a polyamine was confirmed by infrared analysis. After immobilization, the enzyme retained 60% of its initial activity. Highly efficient lactose conversion was achieved in a batch process at 7ºC and 35ºC and was possible to reuse the immobilized enzyme in 16 repeated cycles, at 7ºC, without any drastic decrease in enzyme activity. Km value for the immobilized enzyme in silica based hybrid material was 9.17 mM and for the enzyme immobilized in the film of cellulose/ionic liquid was 11.22 mM, both showing an increase compared with the Km value for free enzyme (1.25 mM), due to the difficulty of access of the substrate to the active sites of the enzyme. The immobilized enzyme did not show any changes in the optimal pH and temperature when compared to the free enzyme in both methods tested.

Interfaces are ubiquitous in our daily life. A good understanding of the interfacial properties between different materials, or a single material in different physical states is of critical importance for us to explore the current world and bring benefits to mankind. In this work, interfacial behavior was investigated with the help of surface analysis techniques, such as quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and atomic force microscopy (AFM), in order to gain better understanding on biofuel conversion, gene/drug delivery, and chemical fixation of CO2. Biomimetic chelator-mediated Fenton (CMF) non-enzymatic degradations on cellulose and chitin thin films was studied by liquid-phase QCM-D and AFM. QCM-D is a powerful tool to monitor the kinetics of hydrolysis of regenerated cellulose and chitin model surfaces. Results from QCM-D and AFM showed that the majority of the biomass of the two model surfaces can be hydrolyzed by the CMF system. The initial degradation rates for both model surfaces by the CMF system are faster than that of the corresponding enzyme systems. The CMF system, which is a good non-enzymatic pretreatment agent for cellulose and chitin, may work on a wide variety of polysaccharide systems. Adsorption of cationic cellulose derivatives onto self-assembled monolayer (SAM) surfaces was investigated using liquid-phase SPR. Results from SPR showed that depending upon the cellulose derivative structure, irreversible adsorption ranging from a monolayer to ~1.6 layers of cellulose derivative were formed on the SAM-COOH surface based upon a charge neutralization mechanism. At low salt concentrations, the long-range electrostatic attraction between the cationic cellulose derivatives (6-PyrCA and 6-MeIMCA) and the SAM surfaces facilitates the formation of a 2-dimensional monolayer. While, for TMACE, the energy gained through the hydrophobic interaction between adjacent long polyelectrolyte branches may afford the electrostatic repulsion and chain entropy penalties, resulting in the formation of 3-dimensional adsorbed polyelectrolyte layers. Adsorption of 1,2-epoxybutane gas molecules onto/into VPI-100 metal–organic frameworks (MOFs) was studied by gas-phase QCM-D experiments. Results from QCM-D demonstrated that VPI-100 (Ni) MOFs have higher irreversible adsorption per unit cell (θ) and faster diffusion coefficients (D) than VPI-100 (Cu) MOFs. The presence of bound counter-balancing ions on the metallo-cyclam core was attributed as the cause of the higher θ and faster D through the Ni analogue, which suggests the MOF-epoxide interaction occurs at the metallo-cyclam. This study shed light upon tuning MOF structures for better CO2 sorption and epoxide activation to gain higher catalytic efficiency. Finally, in operando high energy X-ray diffraction (HEXRD) was used to monitor the phase transition of the NaxNi1/3Co1/3Mn1/3O2 cathode material during the sintering process. The first charge/discharge cycle of the NaxNi1/3Co1/3Mn1/3O2 cathode materials in different phases were also studied by in operando HEXRD. It was found that the intergrowth P2/O1/O3 cathode (NCM-Q cathode) can inhibit the irreversible P2–O2 phase transition and simultaneously improve the structural stability of the O3 and O1 phases during cycling. The NCM-Q cathode with triple-phase integration demonstrates highly reversible phase evolution during high voltage cycling, possibly leading to a highly reversible capacity and good cycle stability.
Doctor of Philosophy
Interfaces and surfaces are everywhere. Many critical processes, such as molecular recognition, catalysis, and charge transfer, take place at interfaces. The surfaces of plants and animals provide barriers from pathogens, prevent damage from mechanical impacts, detect external stimuli, etc. Inside the human body, nutrition and oxygen are adsorbed through interactions between substances and cell surfaces. Investigations of interfacial behaviors may help us understand our current world better and bring benefits to mankind. In this dissertation, the interface between bio-renewable natural polymers and biomimetic chelators, the interface between a self-assembled monolayer and cationic cellulose derivatives, and the interface between metal–organic frameworks (MOF) and 1,2-epoxybutane gas molecules, were studied with a quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and atomic force microscopy (AFM), to gain insights into biofuel conversion, gene/drug delivery and chemical fixation of CO2, respectively. Additionally, thermally and electrochemically induced phase transitions in sodium-ion battery (SIB) cathode materials were probed via in operando high energy X-ray diffraction (HEXRD). Biomimetic chelator-mediated Fenton (CMF) non-enzymatic degradations of cellulose and chitin thin films were studied by liquid-phase QCM-D and AFM. It was found that the majority of the biomass of the two model surfaces can be degraded by the CMF system. Adsorption of cationic cellulose derivatives onto self-assembled monolayer (SAM) surfaces was investigated using liquid-phase SPR. It was found that both the absorbed layer conformation and the absorbed amount depend upon the interplay between long-range electrostatic interactions and short-range interactions. Adsorption of 1,2-epoxybutane gas molecules onto/into VPI-100 MOFs was studied by gas-phase QCM-D experiments. Data from QCM-D revealed the irreversible gas molecule absorption onto/into MOFs and shed light upon tuning MOF structures for better CO2 sorption and epoxide activation to gain higher catalytic efficiency. Finally, the in operando high energy X-ray diffraction (HEXRD) was used to probe thermally and electrochemically induced phase transitions in sodium-ion battery (SIB) cathode materials. It was found that the NCM-Q cathode with triple-phase integration demonstrates highly reversible phase evolution during high voltage cycling, possibly leading to a highly reversible capacity and good cycle stability.

Le cannabis sativa est l'une des drogues les plus consommées dans le monde. Le THC, sa principale composante psychoactive, représente un facteur de risque de pathologies mentales, telles que le trouble de la consommation de cannabis, la dépendance et la psychose. Le THC a un effet biphasique, de fortes doses de THC provoquent une hypoactivité et une aversion, tandis que de faibles doses de THC provoquent une hyperactivité et une récompense. Le THC agit sur le récepteur aux cannabinoïdes de type 1 (CB1), dont la signalisation est biaisée avec différents transducteurs pouvant véhiculer une voie spécifique selon différentes conditions. Il a été prouvé que la signalisation biaisée est pertinente dans la découverte de médicaments et la compréhension de la signalisation CB1 est essentielle pour le développement de médicaments à base de cannabinoïdes. Même si il a été montré que différentes doses de THC entraînent des effets comportementaux, cellulaires et moléculaires différents, le lien entre ces phénomènes n'a jamais été étudié.En outre, il a été découvert que la pregnénolone (PREG) est un modulateur allostérique endogène biaisé du CB1, en étant un inhibiteur de signalisation spécifique du récepteur CB1 (CB1-SSi) et capable de bloquer des comportements induits par le THC. Comme la PREG est un précurseur de stéroïde, son administration à forte dose peut induire la production de stéroïdes, avec d'éventuels effets secondaires.Ainsi, dans un but thérapeutique, des composés CB1-SSi analogues à la PREG ont été synthétisés, ayant le même potentiel thérapeutique que la PREG, mais sans être métabolisés en stéroïdes. Le CB1-SSi étudié ici est le composé CB1-SSi leader, l’AEF0117.Le premier objectif de ce travail était de comprendre les voies de signalisation intracellulaires selon des doses faibles, moyennes et élevées de THC, conduisant à respectivement l'hyperlocomotion, l'asociabilité et l'hypolocomotion chez la souris.Le second objectif était de comprendre le mécanisme d'action de l’AEF0117 et sa capacité à bloquer les effets comportementaux et moléculaires du THC à faibles, moyennes et fortes doses.La thèse est divisée en cinq parties. L'introduction sert à préfacer les concepts du système endocannabinoïde, ainsi que l'abus de cannabis chez l'homme et les effets comportementaux du THC chez la souris, comme l'hyperlocomotion, l'asociabilité et l'hypolocomotion. L'état de l'art de la signalisation CB1 impliquant le système CB1 biaisé est décrit avec un accent particulier sur les inhibiteurs spécifiques de la signalisation CB1 (CB1-SSi), en particulier la pregnénolone endogène (PREG), et son analogue synthétique, l’AEF0117.L'article Zanese*, Tomaselli* et al, 2020 (publié dans J. Neurosci. Methods) porte sur la validation de la technique analytique à haut débit (AlphaLISA) de choix dans cette étude pour la détection de la phosphorylation des protéines dans les lysats de tissu cérébral.L'article de Tomaselli et al. (à soumettre) est consacré à l'étude de faible dose de THC qui provoque l'hyperlocomotion chez la souris. Les principales données ont révélé que le THC via CB1 recrute la voie de signalisation β-Arrestin1-PI3K-Akt-GSK3β, dans les zones du cerveau riches en CB1 et pertinentes pour l'activité locomotrice (NAc, Str, CB), qui conduit à l'hyperlocomotion. En outre, PREG et AEF0117 peuvent bloquer l'hyperlocomotion et les modifications de la signalisation CB1 induite par le THC.La troisième partie représente les études sur les effets du THC à des doses moyennes et élevées qui induisent respectivement un comportement asocial et une hypolocomotion. Chaque dose de THC induit des altérations spécifiques des voies de signalisation intracellulaires CB1 et le traitement avec l’AEF0117 réverse les deux comportements.La discussion générale aborde ensuite le rôle des voies CB1 spécifiques dans la dépendance et la psychose induites par le THC, et propose un mécanisme d'action pour les composés CB1-SSi, dont l’AEF0117
Cannabis sativa is among the most abused drugs worldwide. THC, its main psychoactive component, represents a risk factor of several mental pathologies, such as cannabis use disorder, addiction, and psychosis. Being a biphasic drug, high doses of THC cause hypoactivity and aversion, whereas low doses of THC cause hyperactivity and reward. THC acts on the type-1 cannabinoid receptor (CB1), one of the most abundant G-protein coupled-receptors (GPCRs) in the brain, whose signaling is biased, meaning that different transducers can carry specific pathway following different conditions. Biased signaling was proven to be extremely relevant in drug discovery and understanding CB1 signaling in pathologic conditions is essential for cannabinoid-based drug development. It is known that different doses of THC bring along different behavioral, cellular, and molecular outcomes. However, the link between those phenomena has never been investigated.Thus, for a therapeutic purpose PREG-like CB1-SSi compounds have been synthetized that share the same PREG therapeutic potential, but cannot be metabolized in downstream steroids. The CB1-SSi studied in the current work is the CB1-SSi lead compound, AEF0117.The first aim of the current work was to understand the intracellular signaling pathways following low, medium, and high doses of THC, leading to three distinct known behavioral outputs in mice, hyperlocomotion, asociability, and hypolocomotion, respectively.The second aim of the thesis was to understand the mechanism of action of AEF0117, and its capability to block the behavioral and molecular effects of THC at low, medium, and high doses.The doctoral dissertation is divided into five main parts. The introduction serves to preface the concepts of the endocannabinoid system, as well as cannabis abuse in humans and the counterpart behavioral outcomes of THC in mice, including hyperlocomotion, asociability, and hypolocomotion. The state of the art of CB1 signaling involving the biased CB1 system is described with particular emphasis on CB1 Signaling Specific Inhibitors (CB1-SSi), in particular the endogenous pregnenolone (PREG), and its synthetic analogue, the lead CB1-SSi compound, AEF0117.The article Zanese*, Tomaselli* et al., 2020 (published in J. Neurosci. Methods) oversees the validation of the high throughput analytical technique (AlphaLISA) of choice in this study for detection of protein phosphorylation in brain tissue lysates.The article Tomaselli et al. (to be submitted), is devoted to the studies of the low dose of THC that causes hyperlocomotion, with the discovering of its related intracellular CB1 signaling pathway, along with the signaling transducer involved in the CB1-rich brain areas relevant for locomotor activity (NAc, Str, CB). The main data revealed that THC via CB1 recruits the β-Arrestin1-PI3K-Akt-GSK3β signaling pathway that lead to hyperlocomotion. Furthermore, both PREG and AEF0117 were able to block the THC-induced hyperlocomotion and altered signaling in mice.The third part of the data represent studies on the effects of THC at medium and high doses that induce asocial behavior and hypolocomotion, respectively. Each dose of THC induced specific alterations in the CB1intracellular signaling pathways in the most CB1-rich brain areas, and the treatment with AEF0117 rescued both behaviors.The general discussion then addresses conclusions and perspectives, highlighting the role of specific CB1 pathways in THC-induced addiction and psychosis, and proposes a mechanism of action for CB1-SSi compounds, including AEF0117

Ved består huvudsakligen av tre typer av polymerer, cellulosa, hemicellulosa och lignin. Lignin bildas i naturen genom enzymatiskt initierad oxidativ koppling av tre olika typer av fenylpropan-enheter. Dessa bygger genom olika kol-kol- och kol-syre-bindningar upp en amorf tredimensionell polymer. När kemisk massa tillverkas bryts lignin ner och löses ut i kokluten. Luten innehåller de förbrukade kokkemikalierna och bränns generellt i en sodapanna för att regenerera kemikalierna och producera ånga. Sodapannan är emellertid dyr. Därför har den blivit produktionsbegränsande på många massabruk. Att avlägsna en del av ligninet från avluten vore därför önskvärt och att finna ekonomiskt intressanta produkter baserade på lignin från svartlut är därför ett viktigt forskningsområde .

Ett lämpligt område för ligninprodukter vore som tillsatts i oblekt massa. Oblekt massa används till stor del för tillverkning av kraftliner, topp- och bottenskikten på wellpapp. När lådor av wellpapp lagras i containrar som färdas över haven, förändras den relativa luftfuktigheten. Detta gör att lådorna kollapsar lättare än om de skulle ha lagrats vid konstant luftfuktighet, även en hög sådan. Detta är på grund av det så kallade mekanosorptiva- eller accelererade krypfenomenet. Genom tillsatts av våtstyrkemedel till kraftliner eller behandla den med hydrofoba ämnen, finns indikatoner på att mekanosorptiva effekten skulle kunna minska.

För att försöka minska den effekten har ett lågmolekylärt kraftlignin, som utvunnits med hjälp av tvärsflödesfiltrering av svartlut och svavelsyrafällning, använts. Genom derivatisering av detta lignin med linolja erhölls ett hydrofobt ligninderivat som uppvisar strukturella likheter med biopolymeren suberin. När detta suberinlika ligninderivat tillsätts till massa verkar det mekanosorptiva krypet minska. När lågmolekylärt lignin används tillsammans med ligninradikalinitiatorerna lackas eller mangan(III) i kraftlinermassa erhålls dessutom en våtstyrka på ca 5% av torrstyrkan. Efter aminering av detta lignin gav en tillsatts till kraftlinermassan en våtstyrka på upp till 10% av torrstyrkan. Det finns indikationer på att det mekanosorptiva krypet samtidigt minskar när dessa behandlingar görs som ger upphov till ökad våtstyrka.

Wood consists mainly of three types of polymers; cellulose, hemi cellulose and lignin. Lignin is formed in nature through enzymatic initiated oxidative coupling of three different kinds of phenyl propane units. These form by various carbon-carbon and carbon-oxygen bonds, an amorphous three-dimensional polymer. As chemical pulp is produced, lignin is degraded and dissolved into pulping liquors. These liquors contain the spent cooking chemicals and are generally burnt in a recovery boiler to regenerate cooking chemicals and produce steam. However, the recovery boiler is expensive. Hence, it has become the bottleneck for production in many pulp mills. Removal of some lignin from the spent cooking liquor would, for that reason, be desired and valuable products based on lignin from cooking liquors are searched for.

One suitable area for lignin products would be as additive in unbleached pulp. A major product from unbleached pulp is kraftliner, the top and bottom layers of corrugated board. When boxes of corrugated board are stored in containers travelling overseas the relative humidity is varying. This makes the boxes collapse more easily than if they were stored at constant humidity, even a high one. This is due to the so called mechano-sorptive or accelerated creep phenomenon. By addition of wet strength additive to kraftliner or treating it with hydrophobic compounds there are indications on that the mechano-sorptive effect would decrease.

Trying to decrease this effect, low molecular weight kraft lignin has been used. It was obtained by cross-flow filtration of black liquor and precipitation by sulphuric acid. By derivatisation of this lignin by linseed oil, a hydrophobic lignin derivative was obtained, similar in structure to units in the biopolymer suberin. As this suberin-like lignin-derivative was added to pulp the mechano-sorptive creep seemed to be lowered. Furthermore, when the low molecular weight lignin was used together with the lignin radical initiators laccase or manganese(III) in kraftliner pulp, a wet strength of about 5% of dry strength was obtained. An amination treatment of this lignin and addition to kraftliner pulp resulted in a wet strength of up to 10% of dry strength. There are indications of that the mechano-sorptive creep also decreases as these treatments, resulting in increased wet strength, are made.

La membrane des granules de secretion des cellules chromaffine est capable de gelifier l'actine de facon calcium dependante. Le facteur de gelation associe a la membrane est la godrine, proteine de la famille de la spectrine. L'auteur demontre que la godrine est impliquee dans le processus de liberation des catecholamines, les proteines contractiles etant impliquees dans ce phenomene

Parmi les énergies renouvelables, l’énergie solaire est la plus puissante. L’élément clé des DSSCs est le photosensibiliseur, par lequel la génération de photocourant est possible. L’autre élément important est l’électrolyte. Les liquides ioniques (Ils) sont utilisés en tant qu’électrolytes dans les DSSCs du fait de leurs propriétés chimiques: pression de vapeur basse, haute résistance thermique et chimique, polarité et phase modulables, etc. L’objectif de cette thèse est de comprendre les processus photophysiques dans les colorants dérivés d’indolines dans les solvants moléculaires (MS) et les mélanges IL/MS. L’influence du solvant sur les propriétés spectroscopiques de D131, D102, D149 and D205 est d’abord étudiée par spectroscopie stationnaire d’absorption et de fluorescence. Ensuite, la spectroscopie résolue en temps est employée pour étudier leur photophysique et sa dépendance au solvant. Ces expériences ont permis de démontrer l’influence des paramètres d'aptitude de donneur de liaison hydrogène et d'accepteur de liaison hydrogène des solvants. Le rôle majeur de la dynamique de solvatation dans la dynamique des états excités de ces colorants a été montré. Ce phénomène a été suivi dans les mélanges IL/MS en utilisant une sonde fluorescente classique, C153, et des techniques de fluorescence résolues en temps et de dynamique moléculaire. Les réponses de solvatation multi-régimes de ces mélanges sont dirigées par le renforcement de la liaison hydrogène entre la sonde et les composants des mélanges. Les résultats de cette these apportent beaucoup à la compréhension des processus photophysiques fondamentaux régissant les sensibiliseurs et les électrolytes dans les DSSCs
Among all the renewable energy sources, solar energy is the most powerful source far ahead wind or geothermal energies. The first key component of DSSCs is the photosensitizer. It is through this component that the most important steps of photocurrent generation are possible. On the other hand, ionic liquids (ILs) have been proposed as electrolyte for DSSCs due to their peculiar properties: low vapor pressure, high thermal and chemical robustness, tunability of polarity and phase behaviour etc. The objective of this thesis was to get an understanding of the photophysics in the indoline derivated dyes in molecular solvents (MS) and in the IL/MS mixtures. Firstly, the solvent dependence of the spectroscopic properties of D131, D102, D149 and D205 was studied by the steady-state UV-Vis absorption and fluorescence spectroscopy. Then, time-resolved spectroscopy was used to elucidate their photophysics and its solvent dependence. These experiments helped to discern the influence of the hydrogen bond donor and acceptor abilities of the solvent. The solvation dynamics was shown to play a major role in the excited state dynamics of these dyes. This process in IL/MS mixtures was elucidated using the classic fluorescent probe C153 by the means of time-resolved spectroscopy and MD simulations. The complex multi-regime solvation response in these systems was shown to be shaped by the strengthening of the hydrogen bonding between the probe and the mixture components. The results of this thesis work contribute to the fundamental understanding of the photodynamics of the sensitizer and the response of the electrolyte used in the DSSCs

Après avoir caractérisé les propriétés électriques des cellules mélanotropes de grenouille en culture primaire, il a été, dans le cadre d'une étude couplage stimulus-sécrétion, exploré les effets de 3 signaux neuroendocriniens: la thyrolibérine (TRH), l'acide gamma-aminobutyrique (GABA) et l'acétylcholine (ACH), en utilisant les techniques de patch clamp et de perfusion

L’objectif principal de ce travail est la modification chimique des fibres cellulosiques, afin d'améliorer leurs propriétés interfaciales lors de leur utilisation comme renforts dans des matériaux composites à matrice polymère organique (polystyrène). La synthèse d'un nouvel agent de couplage pour le système cellulose-polystyrène a été entreprise par la voie de copolymérisation cationique. Une caractérisation complète de cet agent de couplage a été faite par ftir, analyse élémentaire, #1h-nmr, calorimétrie différentielle (dsc) et chromatographie par exclusion stérique (ces). La réactivité de ce copolymère a été vérifiée vis-a-vis des oh et des amines primaires par ftir. Les caractéristiques essentielles pour pouvoir l'utiliser comme agent de couplage sont : une bonne miscibilité avec le polystyrène (matrice), de longues chaînes (mn 20000) et la présence des groupements réactifs (isocyanates) sur la chaîne polymère. A titre comparatif, d'autres agents de couplage ayant des structures et des masses différentes ont été utilisés. Deux d'entre eux portent des anhydrides comme fonctions réactives vis-à-vis de la cellulose. La modification chimique des charges cellulosiques a été vérifiée par ftir, analyse élémentaire, microscopie a balayage (meb). De plus, l'énergie de surface des diverses dérives cellulosiques a été mesurée par goniométrie (angle de contact) et chromatographie inverse (igc). L’imperméabilisation des surfaces cellulosiques vis-à-vis des liquides polaires a été vérifiée. L’adhésion (cisaillement interfacial) entre la cellulose et le polystyrène a été mesurée par des techniques micromécaniques sur composites monofilamentaires. Les techniques utilisées ont été la multifragmentation et le déchaussement ('pull-out'). POUR LES COMPOSITES A BASE DE FIBRES CELLULOSIQUES COURTES, L'EFFET DU RENFORCEMENT A ETE VERIFIE A L'AIDE DE LA SPECTROSCOPIE DYNAMIQUE (DMA). LES PARAMETRES SUIVANTS ONT ETE ETUDIES : TAUX DE RENFORT ET FACTEUR DE FORME (LONGUEUR/DIAMETRE). LE MODELE D'HALPIN-KARDOS REPRESENTE CORRECTEMENT LE COMPORTEMENT DE NOS MATERIAUX.

La myopathie myofibrillaire est une maladie neuromusculaire à évolution lente caractérisée par de graves troubles musculaires causés par des mutations dans le gène codant pour des protéines du cytosquelette. L'un des gènes affectés en relation avec le développement de la MFM est DES. Des mutations dans le gène de la desmine entraînent des myopathies des muscles squelettiques et cardiaques. Cependant, les évènements qu'elles entraînent et qui sont à l’origine des phénotypes pathologiques cardiaques restent mal connus. Mon objectif est de créer un modèle in vitro de MFM basé sur des cellules souches pluripotentes humaines afin d'étudier le rôle des mutations spécifiques dans la desmine sur le développement et la fonction des cellules cardiaques. Pour atteindre cet objectif, en collaboration avec les docteurs A. Behin, K. Wahbi et la société Phenocell, nous avons généré des iPSC à partir des cellules sanguines périphériques de patients souffrant d'une forme de cardiomyopathie induite par une mutation de la desmine. Les lignées iPSC générées contenant les mutations du gène codant la desmine ont permis d’étudier le rôle d’une mutation dans la spécification et la fonction des cardiomyocytes. La bioénergétique mitochondriale, la structure cellulaire et la fonction contractiles ont été évaluées au niveau cellulaire. En conclusion, il convient de noter que les mutations de la desmine conduisent à une désorganisation des structures des sarcomères dans les cardiomyocytes et à une perturbation de l'expression des protéines mitochondriales. Ce qui conduit à une altération des fonctions de la mitochondrie. Ces données permettent d’améliorer notre compréhension des mécanismes moléculaire qui sous-tendent le développement de la MFM
Myofibrillar Myopathy is a slowly progressive neuromuscular disease characterized by severe muscular disorders caused by mutations in the gene encoded cytoskeletal proteins. One of the genes described in connection with the development of MFM is DES. Mutations in the desmin gene lead to skeletal and cardiac muscles myopathies. However, the cardiac pathological consequences caused by them remain poorly understood. My objective is to create an in vitro human stem cell model of MFM to specifically investigate the role of patient-specific mutations in desmin on cardiac lineage development and function. To achieve that objective, in collaboration with Drs. Behin and K. Wahbi and Phenocell, we generate patient-specific iPSC from peripheral blood cells of the patient suffering severel form of desmin-deficient cardiomyopathy. The generated iPSC lines carrying DES gene mutations enable a powerful examination of the role of desmin mutation on cardiomyocyte specification and function. Bioenergetic, structural, and contractile function will be assessed in a single cell. In conclusion, it should be noted that desmin mutations lead to a disorganization of sarcomere structures in cardiomyocytes and to a perturbation of mitochondrial protein expression. This leads to a distortion of functions in the mitochondria. These data facilitate the understanding of the molecular pathway underlying the development of desmin-related myopathy. And the system we have created could also allow us to better evaluate the correlation between the desmin genotype and phenotype in terms of effect on the heart

The present PhD thesis deals with the consolidation of stone materials, using nanotechnologies and composite materials. Nanocomposites were developed and tested for surface consolidation treatments of unbaked earth (adobe breaks) - one of the most common building technique worldwide spread - using silica nanoparticles, calcium hydroxide nanoparticles and a cellulose derivative. A kinetic study on the carbonation of calcium hydroxide nanoparticles was carried out by means of accelerated carbonation of four commericial alcoholic dispersions and FTIR spectroscopy.

Neuartige Cellulosederivate werden ausgehend von kommerziellen Celluloseethern synthetisiert. Aufgrund der guten Löslichkeit der Celluloseether in polaren Lösungsmitteln erfolgt eine homogene Reaktionsführung, wodurch eine regelmäßige Verteilung der Sulfatgruppen entlang der Polymerkette gewährleistet wird. Durch Variation der Reaktionsparameter wie Sulfatierungsmittel, Lösungsmittel, Reaktionszeit und -temperatur erfolgte die Synthese zahlreicher Celluloseethersulfate mit unterschiedlichen Eigenschaften bezüglich Sulfatierungsgrad und kinematischer Viskosität. Durch Bestimmung des Schwefelgehaltes und entsprechender Berechnungen konnten die Anzahl der Sulfatgruppen im Molekül (DSSul) ermittelt werden, wobei die Werte für die synthetisierten Proben im Bereich zwischen DSSul = 0.1 bis DSSul = 2.7 lagen. Der Abbau der Polymerkette wurde ebenfalls durch die Reaktionsbedingungen gesteuert, sodass sowohl Produkte mit hohen (1698 mm2/s) als auch sehr niedrigen (2 mm2/s) kinemtischen Viskositäten resultierten. Wasserlöslichkeit der Produkte wurde durch Trübungsmessungen von 1%igen wässrige Lösungen und der daraus erhaltenen geringen Trübungswerte (NTU < 10) ermittelt. Die Funktionalisierung der Celluloseether mit Sulfatgruppen konnte mittels spektroskopischer Methoden nachgewiesen werden. In 13C-NMR-Spektren von Hydroxypropylcellulosesulfaten wurden zusammen-hängende strukturelle Veränderungen mit dem Anstieg des DSSul der Produkte korreliert. Durch charakteristische Signale im Bereich der Ether-Kohlenstoffatome und deren Verschiebung wurde belegt, dass die Sulfatierung des Celluloseethers an den freien Hydroxylgruppen der Etherseitenkette erfolgte. Mittels FT-RAMAN-Spektroskopie konnten für Sulfatgruppen charakteristische Banden der in den Spektren der sulfatierten Celluloseether nachgewiesen und zugeordnet werden. Aufgrund der ionischen Sulfatgruppen dissoziieren die Celluloseethersulfate in Wasser in geladene Polymerketten. Dadurch ist in Gegenwart von kationischen Polyelektrolyten (polyDADMAC) die Bildung von Polyelektrolytkomplexen in Form von Kapseln und Folien/Membranen möglich. Die Fähigkeit solcher Polyelektrolytkapseln aus Celluloseethersulat und polyDADMAC zu Verkapselung von Substanzen und deren anschließende Freisetzung wurde am Beispiel der Verkapselung des Fluoreszenzfarbstoffes Rhodamin B gezeigt. Mittels fluoreszenzspektroskopischer Messungen konnte der aus den Kapseln freiwerdende Farbstoff detektiert werden. Anhand der Messungen wurde gezeigt, dass die Farbstofffreigabe im Fall von Rhodamin B abhängig von den Probeneigenschaften ist. Durch die Wahl des Ausgangsstoffes und deren Funktionalisierung mit Sulfatgruppen kann die Farbstofffreisetzung gesteuert werden. Mit zunehmendem DSSul des Celluloseethersulfates verlängert sich die Verweilzeit des Fluoreszenz-farbstoffes in der Kapsel. Zusätzliche Funktionelle Gruppen in der Seitenkette des Ausgangsstoffes führen zu sterischen Hinderung bei der Wechselwirkung mit polyDADMAC, wodurch eine gegenseitige Durchdringung der Polymerketten bei der Ausbildung des Polyelektrolytkomplexes gehindert wird, sodass weniger kompakte Membranstrukturen der Kapseln resultieren. In Zellexperimente mit adhärenten Zelllinien an entsprechenden mit Celluloseethersulfat präpartierten Oberflächen wurde gezeigt, dass die Zelladhäsion durch den Sulfatierungsgrad der Proben beeinflusst wird. Auf Proben mit höherem Sulfatierungsgrad findet eine verbesserte Adhäsion im Vergleich zu Proben statt, die einen geringen Sulfatierungsgrad aufweisen. Demnach wird die Kompatibilität der Zellen auf solche Oberflächen durch die Erhöhung des Substitutionsgrades der Proben begünstigt.

Tese de doutoramento em Química, no ramo de Química Macromolecular, apresentada à Faculdade de Ciências e Tecnologias da Universidade de Coimbra
Probiotics are increasing their popularity in the market, as their health benefits are being progressively recognized by the public. They are already included in some foods and representing global sales above $30 billion. There is, however, a key issue that concerns the scientists: in order to promote their beneficial effects in the host, probiotics must survive the harsh conditions of the gastrointestinal (GI) tract and should be able of reaching the large intestine to enable colonization. A possible approach to overcome this issue is to entrap the bacteria in suitable matrices, which ideally maintain the bacteria viable and culturable along with other preservation compounds through the GI tract and capable to provide its controlled release. This project mainly aimed at developing biopolymer-based systems to be used in food applications. Food and drug administration (FDA) approved cellulose based derivatives were selected and mixed with different polymers/compounds as additives/emulsifiers/prebiotics to enhance the viability of bacteria, create more stable delivery systems and sustain the different storage conditions as well as maintaining the viability for a minimum of 30 days. Therefore, in this work, novel micro- and macroparticles, based on carboxymethyl cellulose (CMC) and chitosan (Cht) (cross-linked or not with genipin), were successfully prepared in aqueous media either by drop-wise addition or via nozzle-spray methods. The crosslinked particles are robust, thermally resistant and less sensitive to pH changes. On the other hand, the physical systems are pH sensitive presenting a remarkable swelling at pH 7.4, while little swelling is observed at pH 2.4. Model probiotic bacteria (Lactobacillus rhamnosus GG) were successfully encapsulated in the CMC-Cht based particles with acceptable viability count. In a subsequent step, different cyclodextrins (CDs) were used in the particle formulation and their potential prebiotic effect evaluated. The morphology of the systems depends on the CD used and this may be related to different “host-guest” interactions between the CDs and the CMC-Cht matrix thus affecting the polymer organization and overall particle microstructure. Among the CDs tested, β-CD was observed to be one of the most efficient molecules to enhance the survival of the cells. In order to improve the developed particles in terms of aggregation and colloidal stability, different food grade compounds were included in the formulations, such as caseinate and soy lecithin. Apart from the micro- and macro particles other methods were used to entrap probiotics such as the formation of water-in-water (W/W) emulsions based on gelatin and CMC. Depending on the conditions, the mixtures can lead to the formation of W/W emulsion droplets and model probiotic bacteria could be successfully entrapped with surprisingly high viability count. Finally, cellulose-based edible films with CMC and HEC (hydroxyethyl cellulose) cross-linked with citric acid (CA) were also developed under mild conditions. Films with tunable mechanical properties and swelling ability could be obtained by varying the HEC/CMC ratio and the amount of CA. It is salient to notice that some of the systems tested can be considered prebiotics since the viability count of model probiotic bacteria, entrapped in CMC-Cht particles, was considerably improved after the incorporation of CDs and gelatin in the formulation. Further studies on the aging and behavior of the particles in simulated gastrointestinal fluids were performed. Particles loaded with caseinate, soy lecithin or cyclodextrins showed an improved viability of LGG even after one month storage at 25 ºC. In most of the cases, matrices were also capable to efficiently protect the cells from the simulated harsh gastric conditions with a remarkable viability in comparison to naked probiotic. The cellulose-based particles developed were also evaluated regarding their effect on an intestinal cell line and the results indicate that the systems are reasonably mild for the cells and thus encouraging for future applications. Overall, all the systems developed in this work could efficiently entrap and preserve viable bacteria thus being promising matrices for food applications. Os probióticos têm visto a sua popularidade no mercado aumentar em grande medida devido ao reconhecimento do público dos seus efeitos benéficos para a saúde. Eles já são incluídos em muitos produtos alimentares que representam um total global de vendas de cerca de 30 mil milhões de dólares. No entanto, existe uma questão central que continua a preocupar os cientistas. Para que os probioticos exerçam os seus efeitos benéficos no hospedeiro eles têm que sobreviver às condições particularmente adversas do sistema gastrointestinal e atingir o intestino grosso com viabilidade aceitável para uma colonização eficiente. Uma possível estratégia para ultrapassar os obstáculos impostos pelo trato gastrointestinal reside na proteção dos probióticos em matrizes apropriadas par ao efeito. Idealmente estes sistemas em combinação com outros compostos serão capazes de manter as bactérias viáveis e cultiváveis ao longo do trato gastrointestinal e promover a sua libertação no sítio apropriado. Este projeto tem como objetivo principal o desenvolvimento de sistemas baseados em biopolímeros para aplicações na área alimentar. Foram selecionados derivados de celulose aprovados pela agência para os alimentos e medicamentos (FDA) e misturados com outros polímeros e compostos como agentes emulsificantes, prebióticos, ciclodextrinas para aumentar a viabilidade das bactérias probióticas e criar vetores de entrega mais estáveis e capazes de resistir a diferentes condições de armazenamento e manter uma viabilidade aceitável durante pelo menos 30 dias. Tendo isto em consideração, neste trabalho foram desenvolvidas novas micro e macro partículas à base de carboximetilcelulose (CMC) e quitosano (Cht) (reticuladas ou não com genipina) em meio aquoso através de um procedimento de adição gota-a-gota ou spray. As partículas reticuladas são robustas e termicamente resistentes e pouco sensíveis a variações de pH. Por outro lado, os sistemas físicos são mais sensíveis às variações de pH apresentando uma turgescência assinalável a pH 7.4 enquanto a turgescência a pH 2.4 é menosprezável. Neste trabalho foram encapsuladas bactérias probioticas modelo (Lactobacillus rhamnosus GG) em partículas de CMC-Cht com viabilidade aceitável. Numa etapa subsequente, diferentes ciclodextrinas (CDs) foram usadas na formação das partículas e avaliado o seu eventual efeito prebiótico. A morfologia dos sistemas é fortemente dependente do tipo de CD usado e tal fato pode estar relacionado com as diferentes interações “hospedeiro-hospede” entre CDs e a componentes da matriz de CMC-Cht que eventualmente afetam a organização dos polímeros e microestrutura das partículas. De entre as CDs testadas, a β-CD foi aquela que se mostrou mais eficiente no aumento da viabilidade dos probióticos. De forma a melhorar a estabilidade das partículas em termos de minimizar a agregação, foram usados na formulação diferentes compostos de qualidade alimentar como caseinato de sódio e lecitina. Para além da formação das micro e macro partículas foram desenvolvidos outros sistemas para “aprisionar” os agentes probióticos como emulsões de água-em-água (W/W) à base de CMC e gelatina. Dependendo das condições, estas misturas podem levar à formulação de emulsões onde é possível aprisionar de forma satisfatória e com surpreendente elevada viabilidade as bactérias probióticas modelo. Finalmente foram ainda desenvolvidos filmes comestíveis à base dos derivados de celulose CMC e hidroxietilcelulose (HEC) reticulados com ácido cítrico. As propriedades mecânicas e de turgescência podem ser ajustadas dependendo do rácio HEC/CMC e concentração de ácido cítrico. È importante notar que alguns dos sistemas desenvolvidos comportam-se como prebióticos pois a viabilidade das bactérias probióticas modelo aumentou consideravelmente depois da incorporação de CDs ou gelatina na formulação. Foram realizados ainda alguns estudos de envelhecimento e comportamento das partículas em fluidos gastrointestinais artificiais. As partículas com caseinato de sódio, lecitina e CDs demonstraram um melhoramento na viabilidade depois de armazenadas um mês a 25 ºC. Na maior parte dos casos, as matrizes polimericas desenvolvidas foram capazes de proteger de forma muito satisfatória as células próbioticas das condições adversas impostas pelos sucos gástricos artificiais resultando em viabilidades assinaláveis em comparação com as bactérias não protegidas. As partículas desenvolvidas à base de celulose foram ainda avaliadas tendo em conta o seu impacto numa linha celular intestinal e os resultados indicam que os sistemas são relativamente inócuos para as células intestinais. De forma geral, os sistemas desenvolvidos no decorrer deste trabalho conseguem de forma eficiente encapsular e preservar a viabilidade dos agente probióticos e portanto podem ser consideradas matrizes promissoras para futuras aplicações alimentares. Keywords: Cellulose derivatives, Probiotics, Prebiotics, LGG, delivery, viability. Palavras-chave: Derivados de celulose, probióticos, prebióticos, LGG, entrega, viabilidade.
Os probióticos têm visto a sua popularidade no mercado aumentar em grande medida devido ao reconhecimento do público dos seus efeitos benéficos para a saúde. Eles já são incluídos em muitos produtos alimentares que representam um total global de vendas de cerca de 30 mil milhões de dólares. No entanto, existe uma questão central que continua a preocupar os cientistas. Para que os probioticos exerçam os seus efeitos benéficos no hospedeiro eles têm que sobreviver às condições particularmente adversas do sistema gastrointestinal e atingir o intestino grosso com viabilidade aceitável para uma colonização eficiente. Uma possível estratégia para ultrapassar os obstáculos impostos pelo trato gastrointestinal reside na proteção dos probióticos em matrizes apropriadas par ao efeito. Idealmente estes sistemas em combinação com outros compostos serão capazes de manter as bactérias viáveis e cultiváveis ao longo do trato gastrointestinal e promover a sua libertação no sítio apropriado. Este projeto tem como objetivo principal o desenvolvimento de sistemas baseados em biopolímeros para aplicações na área alimentar. Foram selecionados derivados de celulose aprovados pela agência para os alimentos e medicamentos (FDA) e misturados com outros polímeros e compostos como agentes emulsificantes, prebióticos, ciclodextrinas para aumentar a viabilidade das bactérias probióticas e criar vetores de entrega mais estáveis e capazes de resistir a diferentes condições de armazenamento e manter uma viabilidade aceitável durante pelo menos 30 dias. Tendo isto em consideração, neste trabalho foram desenvolvidas novas micro e macro partículas à base de carboximetilcelulose (CMC) e quitosano (Cht) (reticuladas ou não com genipina) em meio aquoso através de um procedimento de adição gota-a-gota ou spray. As partículas reticuladas são robustas e termicamente resistentes e pouco sensíveis a variações de pH. Por outro lado, os sistemas físicos são mais sensíveis às variações de pH apresentando uma turgescência assinalável a pH 7.4 enquanto a turgescência a pH 2.4 é menosprezável. Neste trabalho foram encapsuladas bactérias probioticas modelo (Lactobacillus rhamnosus GG) em partículas de CMC-Cht com viabilidade aceitável. Numa etapa subsequente, diferentes ciclodextrinas (CDs) foram usadas na formação das partículas e avaliado o seu eventual efeito prebiótico. A morfologia dos sistemas é fortemente dependente do tipo de CD usado e tal fato pode estar relacionado com as diferentes interações “hospedeiro-hospede” entre CDs e a componentes da matriz de CMC-Cht que eventualmente afetam a organização dos polímeros e microestrutura das partículas. De entre as CDs testadas, a β-CD foi aquela que se mostrou mais eficiente no aumento da viabilidade dos probióticos. De forma a melhorar a estabilidade das partículas em termos de minimizar a agregação, foram usados na formulação diferentes compostos de qualidade alimentar como caseinato de sódio e lecitina. Para além da formação das micro e macro partículas foram desenvolvidos outros sistemas para “aprisionar” os agentes probióticos como emulsões de água-em-água (W/W) à base de CMC e gelatina. Dependendo das condições, estas misturas podem levar à formulação de emulsões onde é possível aprisionar de forma satisfatória e com surpreendente elevada viabilidade as bactérias probióticas modelo. Finalmente foram ainda desenvolvidos filmes comestíveis à base dos derivados de celulose CMC e hidroxietilcelulose (HEC) reticulados com ácido cítrico. As propriedades mecânicas e de turgescência podem ser ajustadas dependendo do rácio HEC/CMC e concentração de ácido cítrico. É importante notar que alguns dos sistemas desenvolvidos comportam-se como prebióticos pois a viabilidade das bactérias probióticas modelo aumentou consideravelmente depois da incorporação de CDs ou gelatina na formulação. Foram realizados ainda alguns estudos de envelhecimento e comportamento das partículas em fluidos gastrointestinais artificiais. As partículas com caseinato de sódio, lecitina e CDs demonstraram um melhoramento na viabilidade depois de armazenadas um mês a 25 ºC. Na maior parte dos casos, as matrizes polimericas desenvolvidas foram capazes de proteger de forma muito satisfatória as células próbioticas das condições adversas impostas pelos sucos gástricos artificiais resultando em viabilidades assinaláveis em comparação com as bactérias não protegidas. As partículas desenvolvidas à base de celulose foram ainda avaliadas tendo em conta o seu impacto numa linha celular intestinal e os resultados indicam que os sistemas são relativamente inócuos para as células intestinais. De forma geral, os sistemas desenvolvidos no decorrer deste trabalho conseguem de forma eficiente encapsular e preservar a viabilidade dos agente probióticos e portanto podem ser consideradas matrizes promissoras para futuras aplicações alimentares.