<p dir="ltr">The goal of this thesis is to design nature-inspired biomimetic materials that recapitulate essential features of tissues for biomedical applications including tissue modeling of drug transport and surgical adhesion.</p><p dir="ltr">The first part of this thesis utilizes collagen and glycosaminoglycans to mimic tissues for preclinical modeling of large-molecule drug transport. We first utilize hydrazone crosslinking chemistry with hyaluronic acid to form interpenetrating networks with collagen at different concentrations. The interpenetrating networks enabled a wide range of mechanical properties, including stiffness and swellability, and microstructures, such as pore morphology and size, that can better recapitulate diverse tissues. The mechanical and microstructural differences translated into differences in transport of the macromolecules of different sizes and charges from these matrices. Large macromolecules were impacted by mesh size, whereas small macromolecules were influenced primarily by electrostatic forces. The tunable properties demonstrated by the collagen and crosslinked hyaluronic acid hydrogels can be used to mimic different tissues for early-stage assays to understand drug transport and its relationship to matrix properties.</p><p dir="ltr">We then explore how the glycosaminoglycans hyaluronic acid, chondroitin sulfate, and heparin in collagen hydrogels influence drug transport via glycosaminoglycan-drug interactions and network development. Incorporating different types and concentrations of glycosaminoglycans led to glycosaminoglycan-collagen hydrogels with a range of collagen networks and negative charge densities to recapitulate different tissue compositions. Hyaluronic acid increased the overall viscosity of the hydrogel matrix, and chondroitin sulfate and heparin altered collagen fibrillogenesis. All three GAGs formed concentration-dependent polyelectrolyte complexes with positively charged macromolecules. Transport of positively charged macromolecules through collagen gels with chondroitin sulfate and high concentrations of heparin was inhibited due to complexation and charge effects. Conversely, collagen with low concentrations of heparin hastened the transport of macromolecules due to the limited collagen network resulting from fibrillogenesis inhibition. Overall, the addition of different GAGs into tissue models can better recapitulate native tissue to accurately predict therapeutics transport through a variety of tissues.</p><p>17</p><p dir="ltr">The second part of this thesis investigates the impact of pH and oxidation on an elastin- and mussel-inspired surgical sealant. We combined sodium periodate, an oxidizer, with an L-3,4-dihydroxyphenylalanine-modified elastin-like polypeptide to elucidate how the crosslinking mechanism and intermediate formation impacted adhesion, cure time, and stiffness. Formulations resisted burst pressures greater than physiological internal pressures. They did not swell and had stiffnesses similar to those of soft tissues, and their gelation times varied from seconds to hours. Small increases in the formulation pH led to the formation of α,β-dehydrodopamine intermediates which facilitated the development of multiple crosslinking networks. The mussel-inspired elastin-like adhesive can serve as a model of mussel proteins to further improve our understanding of mussel chemistry. This study exemplifies the importance of pH and oxidation on the performance of mussel-inspired adhesives in surgical sealing within physiological environments.</p><p dir="ltr">The final part of this thesis explores using biomimetic designs in an outreach activity aimed at engaging high school women in chemical engineering. The design and application of the activity led to increased interest in chemical engineering among the participants. There was greater alignment between students' aspirations and the field of chemical engineering, highlighting the potential for such outreach initiatives to inspire future generations of chemical engineers.</p>

Pu (III) is one of the key elements in the safety assessments of Canadian deep geological repository program (DGR). Sorption is a potential mechanism for retarding radionuclide transport from a DGR to the environment. In the current scenario, Pu (III) is considered to be a dominant radioactive element in the deep geological groundwater. Eu, considered to be a chemical analogue of Pu (III), its sorption behavior is now the target of our research. This thesis investigates the sorption properties of Eu on MX-80 under saline reducing conditions, and highly saline reducing conditions. The thermodynamic sorption modelling of Eu is also need to be applied. A surface sorption model is also developed by applying computer program for Eu (III) on MX-80 to investigate the sorption mechanisms of Eu (III) sorption. / Thesis / Master of Applied Science (MASc)

No description available.

The process of TEMPO-mediated oxidation has gained broad usage towards the preparation of highly charged, carboxyl-functionalized polysaccharides. TEMPO-oxidized nanocelluloses (TONc) of high surface charge and measuring 3 to 5 nm in width have been recently prepared from TEMPO-oxidized pulp. This study examines as-produced and surface-hydrophobized TONc as reinforcing additives in cellulosic polymer matrices. In the first part of the work, covalent (amidation) and non-covalent (ionic complexation) coupling were compared as treatment techniques for the hydrophobization of TONc surfaces with octadecylamine (ODA). Subsequently, TONc and its covalently coupled derivative were evaluated as nanofiber reinforcements in a cellulose acetate butyrate (CAB) matrix. The properties of the resulting nanocomposites were compared with those of similarly prepared ones reinforced with conventional microfibrillated cellulose (MFC). It was found that both ionic complexation and amidation resulted in complete conversion of carboxylate groups on TONc surfaces. As a result of surface modification, the net crystallinity of TONc was lowered by 15 to 25% but its thermal decomposition properties were not significantly altered. With respect to nanocomposite performance, the maximum TONc reinforcement of 5 vol % produced negligible changes to the optical transmittance behavior and a 22-fold increase in tensile storage modulus in the glass transition region of CAB. In contrast, hydrophobized TONc and MFC deteriorated the optical transmittance of CAB by ca 20% and increased its tensile storage modulus in the glass transition region by only 3.5 and 7 times respectively. These differences in nanocomposite properties were attributed to homogeneous dispersion of TONc compared to aggregation of both the hydrophobized derivative and the MFC reference in CAB matrix. A related study comparing TONc with MFC and cellulose nanocrystals (CNC) as reinforcements in hydroxypropylcellulose (HPC), showed TONc reinforcements as producing the most significant changes to HPC properties. The results of dynamic mechanical analysis and creep compliance measurements could be interpreted based on similar arguments as those made for the CAB-based nanocomposites. Overall, this work revealed that the use of TONc (without the need for surface hydrophobization) as additives in cellulosic polymer matrices leads to superior reinforcing capacity and preservation of matrix transparency compared to the use of conventional nanocelluloses. / Ph. D.

The adsorption behavior of silicic acid and arsenite alone and competitively on goethite over a broad pH range (3-11) at environmentally relevant concentrations was investigated utilizing pH adsorption data and zeta potential measurements. Both addition scenarios (Si before As(III) and As(III) before Si) were examined. The results of the adsorption experiments and zeta potential measurements were then used to model the single ion and competitive ion adsorption on goethite with the CD-MUSIC model implemented in the FITEQL 4.0 computer program. Silicic acid adsorption was reduced by the presence of arsenite for all but one of the adsorption scenarios examined, while in contrast silicic acid had little effect upon arsenite adsorption. However, the presence of silicic acid, regardless of the addition scenario, dramatically increased the arsenite equilibrium solution concentration over the entire pH range investigated. The CD-MUSIC model was able to predict the single ion adsorption behavior of silicic acid and arsenite on goethite. The modeled zeta potential data provided further evidence of the CD-MUSIC model's ability to describe the single anion adsorption on goethite. Our model was also able to collectively describe adsorption and zeta potential data for the low Si-arsenite adsorption scenario quite well however, our model under-predicted silicic acid adsorption for the high Si-arsenite competitive scenario. / Master of Science

Les objectifs de cette thèse sont articulés autour de deux axes principaux : la synthèse et l’étude de cages moléculaires photo-modulables, et la génération de nano-cristaux d’or par photo-catalyse supramoléculaire. Ces deux thématiques sont reliées entre elles par l’exploitation des propriétés photophysiques et photochimiques d’un motif commun, le 9,10-diphénylanthracène (DPA). Dans un premier temps, de nouvelles architectures tridimensionnelles photo-modulables de type cage moléculaire ont été conçues et étudiées. En présence d’oxygène, l’irradiation directe ou sensibilisée du DPA permet de former réversiblement le dérivé endoperoxyde et ainsi moduler les propriétés de complexation de la cage. Les différentes stratégies de synthèse mises en place reposent sur l’exploitation conjuguée de la réactivité de la 2,4,6-trichloro-1,3,5-triazine, et de réactions de chimie « click » (métathèse des oléfines, cycloaddition de Huisgen). L’étude et la modulation des propriétés des reconnaissances ont été effectuées sur des sels de cations alcalins (sodium et césium) et suivies par émission de fluorescence et spectroscopie d’absorption UV-visible. Les résultats obtenus avec deux cages possédant des constantes d'associations élevées (logK = 8,7 pour le cation sodium) montrent une augmentation de la constante d’association d’un facteur 10 et 20 pour respectivement le sodium et le césium entre la forme DPA et la forme endoperoxyde. Dans un second temps, des photocatalyseurs supramoléculaires basés sur le chromophore DPA ont été étudiés en vue de la synthèse de nano-cristaux d’or nus. L’association du chromophore avec des thioéthers permet de former un complexe en phase organique par extraction de sels d’or(III) depuis une phase aqueuse. L’irradiation à 400nm permet la réduction de l’or(III) par transfert d’énergie depuis le 9,10-diphénylanthracène. Les atomes d’or sont ensuite relargués en phase aqueuse pour former des nano-cristaux nus qui ont pu être caractérisés par MET, XPS, AFM et DLS. Par ailleurs, ce procédé est catalytique dans le toluène et un système de réduction en flux continu a été mis au point permettant un turnover moyen de 150. / The goals of this thesis are organized around two major axes: the synthesis and study of photo-gated molecular cages, and the generation of gold nanocrystals by supramolecular photocatalysis. These two themes are connected by the use of the photochemical and photophysical properties of a common chromophore, 9,10-diphenylanthracene (DPA). Three-dimensional photo-gated cage-like architectures were designed and synthesized. Various synthetic strategies based on the combined use of the 2,4,6-trichloro-1,3,5-triazine unit and "click" chemistry reactions (olefin metathesis, Huisgen cycloaddition) were employed for the synthesis. In the presence of oxygen, sensitized or direct irradiation of the DPA chromophore forms the corresponding endoperoxide derivative, thereby modulating the binding properties of the cage. The study and the modulation of the recognition properties were performed on various alkali metal cations and a strong binding of sodium and cesium was evidenced by fluorescence emission and UV-visible absorption spectroscopy. The cages investigated possessed high association constants towards sodium and cesium cations (logK = 8.7 for the sodium cation) which could be reversibly increased by a factor 10 and 20 for sodium and cesium, respectively, upon formation of the endoperoxide. Supramolecular photocatalysis of gold(III) reduction based on the DPA chromophore was also studied for the preparation of uncapped gold nanocrystals. The combination of the DPA chromophore with thioether chains allows the formation of a complex in the organic phase by extraction of gold(III) chloride from an aqueous phase. Irradiation at 400 nm enables the reduction gold(III) by energy transfer from the 9,10-diphenylanthracene followed by oxidation of the solvent. The gold atoms are subsequently released in the aqueous phase to form uncapped nanocrystals characterized using TEM, XPS, AFM, and DLS techniques. Furthermore, the process is catalytic in toluene, where a continuous flow reactor was developed. The latter allowed an average catalytic turnover of 150 to be determined.

Dans les milieux naturels, la matière solide est essentiellement présente sous la forme de (bio)particules molles perméables aux ions et aux flux hydriques. Ces particules sont sans cesse soumises à des perturbations électriques/mécaniques, de telle sorte que les propriétés physico-chimiques des (bio)interphases qu'elles forment avec le milieu évoluent continûment dans le temps. Les (bio)interphases ne sont donc pas nécessairement à l'équilibre durant les processus interfaciaux (interactions électrostatiques, complexation de métaux). Dans ce contexte, nous avons évalué théoriquement l'énergie d'interaction électrostatique à l'équilibre entre (bio)particules molles multicouches de tailles et de densités de charge arbitraires. Puis nous avons déterminé l'impact de la dynamique hors-équilibre des propriétés électriques de (bio)films mous ligands sur leur capacité à former des complexes avec des métaux. Le dernier modèle théorique élaboré a pour objectif l'analyse de la dynamique de (bio)interphases multicouches hétérogènes en régimes d'équilibre et hors-équilibre. Enfin nous avons analysé à l'équilibre, en alliant l'AFM et l'électrophorèse, les propriétés mécaniques et électriques de bactéries E. coli exprimant spécifiquement (ou non) des structures de surface différentes. Toutes ces études ont montré la nécessité de prendre en compte pour l'analyse de la réactivité de (bio)particules dans leur milieu environnant (i) une représentation fidèle des (bio)particules (mollesse mécanique et hydrodynamique, hétérogénéité spatiale de la structure molle) et (ii) l'impact de la dynamique spatio-temporelle des (bio)interphases sur les processus gouvernant leur réactivité / In natural media, the solid matter is mainly present as soft (bio)particles (bacteria, viruses, humic acids) which are permeable toward ions and hydric fluxes. These (bio)particles are unceasingly exposed to electrical/mechanical perturbations, so that the physicochemical properties of (bio)interphases, developed by (bio)particles with the medium, evolve continuously. (Bio)interphases are thus not necessarily at equilibrium during interfacial processes e.g. electrostatic interactions, complexation with metallic contaminants. Under such a context, we evaluated theoretically at equilibrium the electrostatic interaction energy between soft multilayered (bio)particles with arbitrary sizes and charge densities. We then determined the impact of non- equilibrium electric properties of soft ligand polymeric (bio)films on their ability to form complexes with metals. The aim of the last theoretical model developed here is to analyze the dynamics of multilayered heterogeneous (bio)interphases in both equilibrium and non-equilibrium regimes. Finally we analyzed at equilibrium, by coupling AFM and microelectrophoresis measurements, mechanical and electrical properties of bacterial strains Escherichia coli that specifically express (or not) different surface structures (pili, fimbriae, adhesin Ag43). All these studies highlighted the necessity to integrate for the analysis of (bio)particles reactivity with their surrounding medium (i) a close representation of soft (bio)particles (mechanical and hydrodynamic softness, spatial heterogeneity of the soft material) and (ii) the impact of spatiotemporal dynamics of (bio)interphases on the processes governing their reactivity

Les copolymères poly (acétate de vinyle-co-alcool vinylique), désignés par PVA, sont des tensioactifs macromoléculaires obtenus par hydrolyse partielle de poly (acétate de vinyle)(PVAc). Si les propriétés tensioactives des PVA ont pu être corrélées aux caractéristiques moléculaires il n'en est par de même en ce qui concerne les associats du type nanogels présents dans les solutions aqueuses. L'objectif de cette thèse était de caractériser les nanogels par des techniques telles que la diffusion dynamique de la lumière, la chromatographie d'exclusion stérique et la viscosimétrie. 9 PVA, de degrés d'hydrolyse de 73 à 88 mole% et de degrés de polymérisation de 650 à 2500 ont été étudiés. Il est apparu que les nanogels présent dans les PVA de DH =73 mole% et formés par interactions hydrophobe-hydrophobe entre séquences acétate ont des tailles entre 20-40 nm, avec des fractions volumiques de l'ordre de 20-30%. La désagrégation des nanogels par formation de complexes avec des tensioactifs anioniques du type SDS et SDBS a ensuite été démontrée. En faisant appel à la technique de fractionnement par « point de trouble » il est apparu que les chaînes les plus riches en acétate et en particulier celles ayant des longueurs des séquences acétate importantes complexent plus de SDS.Des « copolymères modèles » du type copolymères diblocs PVAc-b-PVOH comportant une séquence hydrophobe PVAc et une hydrophile PVOH ont pu être préparés par polymérisation RAFT, suivie par une réaction click. Une étude préliminaire de la micellisation de tels copolymères a permis de montrer la très grande analogie entre micelles de copolymères à blocs PVAc-b-PVOH et les nanogels de PVA examinés précédemment. / Poly (vinyl acetate-co-vinyl alcohol) copolymers, designated by PVA, are macromolecular surfactants obtained by partial hydrolysis of poly (vinyl acetate) (PVAc). If the surfactant properties of PVA have been correlated with molecular characteristics it is not the same for the colloidal aggregates in aqueous solutions so-called nanogels. The objective of this thesis was to characterize the nanogels using techniques such as dynamic light scattering, size exclusion chromatography and viscometry.9 PVA with degrees of hydrolysis between 73 and 88 mole% and polymerization degrees of 650 to 2500 were studied. It appeared that the nanogels, formed by hydrophobic-hydrophobic interactions between acetate sequences, are the size in the range of 20 to 40 nm with volume fractions between 20 and 30%. The disaggregation of nanogels by complex formation with anionic surfactants such as SDS and SDBS was further demonstrated. By using the "cloud point" fractionation technique it appeared that SDS is complexed by the sequences with high acetate content and in particular those with significant lengths of acetate sequences.As a model system diblock copolymers PVAc-b-PVOH containing a PVAc hydrophobie sequence and a PVOH hydrophilic sequence were prepared by RAFT polymerization, followed by a click reaction. A preliminary micellization study of these copolymers showed a very strong analogy between PVAc-b-PVOH block copolymer micelles and PVA nanogels discussed above.

Le manque de thérapies innovantes en chimiothérapie humaine incite la communauté scientifique à s'intéresser à de nouvelles sources de composés bioactifs. Nous pouvons citer les métabolites secondaires de plantes, auxquels appartiennent les acides hydroxy pentacycliques triterpénoiques (AHPTs) et plus particulièrement les Acides Ursolique (AU), Oléanolique (AO) et Bétulinique (AB). Ces molécules font l'objet de nombreuses études qui tendent à démontrer leurs propriétés : anti-infectieuses, anticancéreuses, antiprolifératives, anti-inflammatoires, hépatoprotectrices. Le principal obstacle à leur utilisation à des fins thérapeutiques, reste l'insolubilité de ces AHPTs dans l'eau. L'objectif de ce travail a donc été d'augmenter leur hydrosolubilité. Dans un premier temps, en accord avec les recommandations et/ou normes existantes, nous avons démontré que le spectre d'activité antibactérienne de l'AU et de l'AO se limitait aux bactéries à Gram positif. Aucun AHPT n'a montré d'activité antifongique. Seul l'AB a montré une activité intéressante sur le Cytomégalovirus humain (hCMV) ; aucune activité antivirale n'ayant été retrouvée sur le Poliovirus. Enfin, l'AB, mais encore plus l'AU ont montré une activité anticancéreuse à l'encontre de cellules modèles de leucémie myéloïde chronique (LMC). Dans un deuxième temps, nous avons procédé à la fabrication et à l'étude de complexes entre les AHPTs et des cyclodextrines. Nous avons retenu la gamma-cyclodextrine (gamma-CD), qui présentait l'avantage de complexer les 3 AHPTs avec une constante de formation « moyenne » à « élevée ». Ces complexes AHPTs :gamma-CD ont été caractérisés en utilisant diverses techniques : chromatographiques, thermiques et spectrométriques. Nous avons conclu à l'obtention de complexes d'inclusion qui ont permis d'augmenter la solubilité des AHPTs. Dans une dernière partie, nous avons évalué les activités biologiques des complexes AHPTs : gamma-CD. Les résultats montrent que les complexes AU : gamma-CD et AO : gamma-CD restent actifs à l'encontre des bactéries à Gram positif (mais avec une efficacité plus faible) ; tandis que le complexe AB : gamma-CD se révèle être actif sur certaines bactéries. Le complexe AB : gamma-CD, et de façon surprenante le complexe AU : gamma-CD présentent une activité antivirale à l'encontre du hCMV. Enfin, la diminution de la cytotoxicité liée à la complexation des AHPTs accroit l'intérêt des molécules d'AU et d'AB sur les cellules de LMC / The lack of innovative therapies in human chemotherapy incites the scientific community to be interested in new sources of bioactive compounds. We can quote the secondary metabolites of plants, to which belong hydroxy pentacyclic triterpene acids (HPTAs) and more particularly Ursolic (UA), Oleanolic (OA) and Betulinic Acids(BA). These molecules are the subjetc of numerous studies which tend to demonstrate their properties: anti-infective, anticancer, antiproliferatives, anti-inflammatory and hepatoprotectrive. The main obstacle to their use in therapeutic purposes stays the insolubility of these AHPTs in the water. Thus the objective of this work was to increase their hydrosolubility. At first, in agreement with the recommendations and/or the existing standards, we demonstrated that the antibacterial spectra of UA and OA are limited to Gram-positive bacteria. No HPTA showed antifungal activity. Only the BA showed an interesting antiviral activity on human Cytomegalovirus (hCMV); no antiviral activity was on Poliovirus. Finally, the BA, but even more UA showed an anticancer activity against cellular model of chronic myeloid leukemia (CML). Secondly, we proceeded to the manufacturing and to the study of complexes between HPTAs and cyclodextrines. We retained gamma-cyclodextrine (gamma-CD), which presented the advantage to complex the 3 AHPTs with a constant of "average" to "raised". These HPTAs:gamma-CD complexes were characterized by using diverse techniques: chromatographic, thermal and spectrometric. We concluded in the obtaining of inclusion complexes which allowed increasing the solubility of the HPTAs. In a last part, we estimated the biological activities of the HPTAs:gamma-CD complexes. The results show that the UA:gamma-CD and OA:gamma-CD complexes remain active against Gram-positive bacteria (but with a weaker efficiency); whereas the BA:gamma-CD complex shows to be active on certain bacteria. The BA:gamma-CD complex, and in a surprising way the UA:gamma-CD complex presents an antiviral activity against the hCMV. Finally, the decrease of the cytotoxicity linked to the complexation of the HPTAs believes the interest of UA and of BA on CML cells

La reconnaissance moléculaire énantiosélective est un processus fondamental et universel qui est au cœur de tous les systèmes biologiques. Ce travail a pour but de contribuer à la compréhension des phénomènes, mis en jeu lors de cette reconnaissance, par l’utilisation de récepteurs artificiels, capables de complexer et discriminer des acides aminés. De par leurs rigidités et leurs modularités fonctionnelles, les calix[4]arènes constituent des plateformes de choix pour la conception de ces récepteurs organisés. Une série de 12 ligands calixarèniques et thiacalixarèniques chiraux homo et hétéroditopiques, portant des groupements fonctionnels dérivés d’acides aminés, a donc été synthétisée. La synthèse de ces ligands a nécessité la mise au point d’une méthode originale et sélective, qui a permis d’obtenir une série de calix[4]arènes mono-O-fonctionnalisés par des groupements fonctionnels variés. Une étude mécanistique a permis de mettre en évidence les intermédiaires réactionnels. Après caractérisation de tous les composés synthétisés, des études de complexation des ligands avec des dérivés tosylés d’acides aminés neutres ont été effectuées. Les investigations, menées par spectrométrie de masse, par microcalorimétrie et par RMN 1H, nous ont permis de mettre en évidence la capacité de certains ligands à complexer et discriminer des acides aminés. La stœchiométrie et les constantes d’association des complexes formés ont ainsi pu être déterminées. Des études par RMN 2D ont permis de déterminer les liaisons impliquées dans la formation des complexes et ont révélé un réarrangement spatial des ligands, au sein des complexes, afin d’améliorer la stabilité de ceux-ci / Molecular recognition is a fundamental and universal process in biological systems. This work aims to contribute to the understanding of phenomena involved in this recognition by the use of artificial receptors able to complex and discriminate amino acids. Because of their rigidity and their functional modularity, calix[4]arenes and thiacalix[4]arenes are good starting materials for the design of these receptors. A series of 12 chiral homo and heteroditopic calix[4]arenes and thiacalix[4]arenes bearing amino acids derivatives has been synthesized. In order to improve the synthesis of heteroditopic receptors, an original and selective method for the preparation of mono-O-functionalized calix[4]arenes was developed. This procedure, based on the de-O-functionalization of 1,3 di-O-substituted calix[4]arenes by titanium tetrachloride (TiCl4), yielded a series of calix[4]arenes, mono-O-substituted by various functional groups (alcohol, halogen, nitrile, ester, alkyne ...). A mechanistic study revealed the formation of two titanium calixarene complexes during the reaction. After characterization of all these compounds, complexation studies of chiral receptors with neutral N-tosyl amino acids derivatives (valine, leucine, and phenylalanine) were done. Various investigations carried out by mass spectrometry, microcalorimetry and 1 H NMR allowed us to establish the ability of some ligands to complex and discriminate amino acids. Stoichiometry and association constants of the complexes were determined. 2D NMR (NOESY, COSY) studies were used to specify the bonds implied in complex formation