Yes / Hydroxyapatite and fluorhydroxyapatite (F)HA nanoparticles were synthesised in the presence of branched poly(acrylic acid)s (PAA) synthesised via reversible addition–fragmentation chain transfer polymerisation and compared to those synthesised in the presence of linear PAA. Analysis of the resulting nanoparticles using Fourier transform infrared spectroscopy, powder X-ray diffraction and transition electron microscopy found that the polymer was included within the nanoparticle samples and affected their morphology with nanoparticles synthesised in the presence of branched PAA being more acicular and smaller overall.

Yes / Functional crosslinked hydrogels were prepared from 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA). The acid monomer was incorporated both via copolymerization and chain extension of a branching, reversible addition–fragmentation chain-transfer agent incorporated into the crosslinked polymer gel. The hydrogels were intolerant to high levels of acidic copolymerization as the acrylic acid weakened the ethylene glycol dimethacrylate (EGDMA) crosslinked network. Hydrogels made from HEMA, EGDMA and a branching RAFT agent provide the network with loose-chain end functionality that can be retained for subsequent chain extension. Traditional methods of surface functionalization have the downside of potentially creating a high volume of homopolymerization in the solution. Branching RAFT comonomers act as versatile anchor sites by which additional polymerization chain extension reactions can be carried out. Acrylic acid grafted onto HEMA–EGDMA hydrogels showed higher mechanical strength than the equivalent statistical copolymer networks and was shown to have functionality as an electrostatic binder of cationic flocculants.

The goal of this research was to characterize the effects of temperature changes on the denitrification process in a biological nutrient removal (BNR) system. Specifically, there were three objectives. First, the effects of temperature changes on denitrification rates by a bacterial population from a BNR system were investigated. Next, the role which PHAs (poly-beta-hydroxyalkanoates) played in the denitrification process were examined. Finally, the effect of temperature changes on the production and consumption rates of PHAs was determined. Sacrificial batch experiments were performed to assess the kinetic and chemical trends present in the denitrification process. Mixed liquor from the last anaerobic zone of a pilot scale BNR system was injected into vials. These vials were pre-purged with nitrogen gas in order to prevent dimolecular oxygen (02) from being entrained in the mixed liquor. Next, the vials were placed on a shaker table for 30 minutes in order to allow all external COD to be consumed. Following this, each vial was injected with nitrates and various macronutrients. This process was repeated for three different sets of batch tests; each set was identical except for the added substrate. One set received no added substrate while the other two received either acetate or glucose. Vials were sacrificed over a period of three hours and analyzed for nitrate, phosphate, PHB (polybeta-hydroxybutyrate), PHV (poly-beta-hydroxyvalerate), glucose and acetate. / Master of Science

Yes / Biosynthetic materials have emerged as one of the most exciting and productive fields in polymer chemistry due to their widespread adoption and potential applications in tissue engineering (TE) research. In this work, we report the synthesis of a poly(ε-caprolactone)-graft-collagen (PCL-g-Coll) copolymer. We combine its good mechanical and biodegradable PCL properties with the great biological properties of type I collagen as a functional material for TE. PCL, previously dissolved in dimethylformamide/dichloromethane mixture, and reacted with collagen using carbodiimide coupling chemistry. The synthesised material was characterised physically, chemically and biologically, using pure PCL and PCL/Coll blend samples as control. Infrared spectroscopy evidenced the presence of amide I and II peaks for the conjugated material. Similarly, XPS evidenced the presence of C–N and N–C=O bonds (8.96 ± 2.02% and 8.52 ± 0.63%; respectively) for PCL-g-Coll. Static contact angles showed a slight decrease in the conjugated sample. However, good biocompatibility and metabolic activity was obtained on PCL-g-Coll films compared to PCL and blend controls. After 3 days of culture, fibroblasts exhibited a spindle-like morphology, spreading homogeneously along the PCL-g-Coll film surface. We have engineered a functional biosynthetic polymer that can be processed by electrospinning. / The EPSRC Centre in Innovative Manufacturing in Medical Devices (MeDe Innovation; EP/K029592/1).

The importance of Poly(3-hydroxybutyrate) (PHB) as a biodegradable material is well known. Due to ever increasing environmental awareness, significant efforts have been made to utilize PHB or its derivatives in producing disposable products. However, brittle mechanical properties of PHB hinder the direct application of this material in useful commodity items. In order to achieve toughened PHB, blending with other polymers which possess high relaxation behavior at room temperature seems attractive. Prior to such development, the fundamental characterization of the relaxation behavior of PHB itself is extremely important in order to assess the effect of any attempt to improve the situation in a quantitative manner. Dielectric thermal analysis was used in the study of the relaxation behavior of melt processed PHB. The approach was largely phenomenological, that was, based on the macroscopic theory of dielectric relaxation. The mean relaxation time of melt processed PHB was evaluated while PHB was undergoing crystallization at room temperature. The experimental conditions were kept as close as possible to actual shelf-life conditions. Dynamic temperature sweep experiments revealed multiple relaxation peaks at the glass transition region. Temperature plane curve resolution revealed, in the early stage of crystallization, two dynamically changing peaks whose behaviors, as the extent of crystallization progressed, were quite opposite in terms of the magnitude of the loss property. By analyzing the temperature dependence of loss property and mean relaxation time, it was concluded that the peak located at the lower temperature is related to pure amorphous chain movement, and the peak located at the higher temperature is related to the movement of amorphous chains which are confined in-between crystalline phases, such as lamellae and spherulites. For the evaluation of the mean relaxation time of binary blends or multiple relaxations arising from homopolymers and copolymers, an empirical model has been developed which is grounded in the theory of linear viscoelasticity with the aim of quantitatively assessing the effect of attempts to improve the toughness of PHB. In the course of data reduction and model development, the majority of empirical dielectric relaxation functions has been reviewed including the Havriliak-Negami model and the Kohlrausch-Williams-Watts stretched exponential function. It was found that the center of relaxation time in the Havriliak-Negami model was skewed toward short time scale of relaxation, while mean relaxation time reflected the relaxation behavior of PHB chains on average, including movement of chains which relax with difficulty as the extent of crystallization progresses. / Ph. D.

The immediate goal of this thesis was the analysis of a three-component system whose major component was water. This analysis was to be the result of a procedure which could be readily extended to more complex systems.

Les tumeurs neuroendocrines (TNEs) sont des maladies rares dont l'incidence augmente depuis le début des années 2000. Lorsque la maladie est métastatique, ce qui arrive dans plus de 20% des cas au diagnostic, peu d'options curatives s'offrent aux patients. La thérapie radionucléidique (PRRT) au ¹⁷⁷Lu-DOTA,Tyr3-octréotate (¹⁷⁷Lu-octréotate) dépendante des récepteurs de la somatostatine a récemment été démontrée plus efficace que le traitement de première ligne actuel, soit les analogues de la somatostatine. Or, les cas de rémission avec la PRRT restent très rares et peu d'agents ont actuellement été utilisés pour en améliorer l'efficacité. Pour l'heure, les traitements pour améliorer la PRRT dans les études cliniques sont principalement tournés vers la combinaison avec des doses thérapeutiques de chimiothérapie. Dans les études précliniques, de nombreuses avenues sont à l'essai que ce soit en augmentant la perfusion des tumeurs, l'internalisation de ¹⁷⁷Lu-octréotate, la létalité des dommages induits par la radioactivité ou en ajoutant un fardeau supplémentaire de dommage à l'ADN. Les inhibiteurs de la poly(ADP-ribose) polymérase (iPARP) interfèrent avec la réparation de l'ADN, principalement la réparation par excision de base. La combinaison d'un iPARP avec la PRRT dans un modèle de sphéroïdes de TNEs humaines bronchopulmonaires (NCI-H727) et pancréatiques (BON-1) a démontré que la combinaison ralentissait davantage la croissance que l'iPARP seul ou la PRRT seule pour les deux lignées cellulaires. Le témozolomide (TMZ) et le 5-fluorouracile (5-FU), deux agents de chimiothérapie couramment utilisés pour traiter les TNEs, ont possiblement un rôle plus vaste que la toxicité à l'ADN. En effet, en exposant les cellules BON-1 au TMZ et au 5-FU à des doses toxiques, mais non létales, une augmentation des récepteurs à la somatostatine et de l'internalisation du ¹⁷⁷Lu-octréotate a été observée. Donc, les traitements combinatoires pour potentialiser la PRRT, notamment les iPARPs et la chimiothérapie, pourraient permettre un meilleur traitement des TNEs. / Neuroendocrine tumors (NETs) are rare diseases, the incidence of which has been increasing over the past 20 years. When the disease is metastatic, which happens in more than 20% of cases at diagnosis, few curative options are available for patients. Peptide receptor radionuclide therapy (PRRT) via somatostatin receptors (SSTR) and ¹⁷⁷Lu-DOTA,Tyr3-octreotate (¹⁷⁷Lu-octreotate) has recently been shown to be more effective than the current first-line therapy, namely somatostatin analogues. However, cases of remission with PRRT remain very rare and few agents have currently been used to improve its effectiveness. At present, treatments to improve PRRT in clinical studies have mainly focused on combination with therapeutic doses of chemotherapy. In preclinical studies, many avenues are being tested whether by increasing tumor perfusion, internalization of ¹⁷⁷Luoctreotate, lethality of radioactivity-induced damage or by adding an additional burden of DNA damage to the tumor. Poly (ADP-ribose) polymerase inhibitors (PARPi) interfere with DNA repair, mainly altering base excision repair pathways. Combining PARPi with PRRT in a spheroid model of bronchopulmonary NETs (NCI-H727) and pancreatic NETs (BON-1) demonstrated that the combination slows growth more than PARPi alone or PRRT alone for both cell lines. Temozolomide (TMZ) and 5-fluorouracil (5-FU), two chemotherapeutic agents commonly used to treat NETs, may have a broader role than conventional cytotoxicity via DNA damage in NET therapy. Indeed, by exposing BON-1 cells to TMZ and 5-FU to toxic, but not lethal doses, an increase in somatostatin receptors and internalization of ¹⁷⁷Lu-octreotate was observed. Acting on various mechanisms to potentiate PRRT is possible with PARPis or chemotherapy. Having multiples targes for potentiation could be key for a better treatment of NETs.

En 2017, Statistique Canada a rapporté qu'un Canadien sur quatre mourra d’un cancer. Chaque jour, nous sommes confrontés à des facteurs environnementaux qui imposent à notre ADN un stress génotoxique. Ce stress peut avoir de graves conséquences au point de menacer notre intégrité génomique, comme les cassures d'ADN double-brin (DSBs). Heureusement, nos cellules ont deux voies principales pour combattre ce type de lésions : la recombinaison homologue (HR) et la Classical Non-Homologous End-Joining (CNHEJ). La voie HR, un type de réparation sans erreur utilisé dans la phase-S du cycle cellulaire, assure une réparation fidèle de la zone endommagée et conserve l'intégrité de l'information génétique. Les individus porteurs de mutations dans les protéines de cette voie, telles que BRCA1 et BCRA2, sont plus susceptibles de développer des cancers du sein et de l'ovaire. Récemment, la clinique a connu une percée majeure dans le traitement du cancer de l'ovaire. Une nouvelle classe de médicaments a été autorisée par la US Food and Drug Administration (FDA) pour traiter les cancers de l'ovaire récurrents qui présentent une HR défective. Ces médicaments inhibent un des acteurs les plus précoces dans la réponse aux dommages à l'ADN (DDR): la PARP-1 (Poly(ADP-ribose) polymerase-1). Lors de l'induction de dommages à l'ADN, la PARP-1 devient fortement activée, conduisant à la production massive de polymères de poly(ADP-ribose) (PAR) générés à partir de l'hydrolyse du nicotinamide adénine dinucléotide. Ce polymère agira comme une plateforme pour recruter des facteurs de réparation de l'ADN au site de réparation. L'application clinique réussie des inhibiteurs de la PARP (PARPi) vient des observations où les mutations ou l'extinction de BRCA1/2 entraînent une diminution de l'activité HR. L'inhibition de la PARP-1 combinée à cette déficience en HR favorise la mort cellulaire, un phénomène appelé létalité synthétique. Trois PARPi sont actuellement autorisés par la FDA et sont utilisés pour le traitement du cancer gynécologique. Malgré l'efficacité thérapeutique de ces inhibiteurs, les mécanismes induisant une régression tumorale ne sont pas complètement compris. Ainsi, il devient extrêmement important de déchiffrer davantage ces mécanismes pour atteindre le plein potentiel des PARPi. Pour ce faire, une recherche fondamentale sur les fonctions des PARPs, et de leurs partenaires dans la DDR, est essentielle et constitue l'objectif général de cette thèse. Durant mon doctorat, nous avons étudié l'influence de la PARP-1 dans la voie HR au moment de l'étape initiale de la résection, qui est essentielle pour l'élimination de l'ADN endommagé. Certaines études ont montré l'implication de la PARP-1 dans le recrutement de la protéine de résection MRE11. Ici, nous démontrons que la PARP-1 a une nouvelle fonction dans la résection des DSBs et nous proposons un nouveau modèle pour expliquer la létalité synthétique observée dans les tumeurs avec une HR défective. Pour compléter l'objectif de ce doctorat, nous avons étudié les rôles régulateurs de la PARP-1 au cours du processus HR, mais plus tard dans la résolution des lésions, c'est-à-dire au maximum de la formation des foyers RAD51, une étape cruciale pour la réparation efficace des DSBs via la HR. Nous avons observé que le PAR-interactome (PARylome) est, à ce moment, fortement enrichi en protéines impliquées dans le métabolisme de l'ARN. Plusieurs des protéines les plus abondantes étaient constituées d’hélicases d’ADN et d’ARN, et de facteurs de transcription. Puisque certains de ces gènes sont mutés dans les tumeurs, ils pourraient théoriquement être des cibles prioritaires pour une utilisation conjointe avec des PARPi. Nous avons également étendu notre étude de la PARylation à la chromatine, au niveau des histones. Nous avons constaté que les queues d'histones ne sont pas les seules cibles de la PARP-1 et que les domaines globulaires centraux sont également PARylés. Finalement, le grand intérêt clinique de la PARP-1 méritait une analyse approfondie de son expression systémique. Ainsi, j'ai terminé mes études en décrivant la distribution et l'abondance tissulaire de la PARP-1 dans les organes simiens, avec l'objectif principal de fournir des informations précieuses quant à l'efficacité potentielle des PARPi ou sa résistance, dans un tissu donné et maladies apparentées. En résumé, cette thèse fournit de nouvelles informations importantes sur les mécanismes orchestrés par la PARP-1 lors de la réponse aux DSBs, y compris les réseaux protéiques complexes engagés dans le remodelage des fonctions cellulaires nécessaire au maintien de l'intégrité génomique. / In 2017, Statistics Canada reported that one out of four Canadians will die of cancer. Every day, we face environmental factors that burden our DNA with genotoxic stress. This stress can lead to severe types of DNA damage that can threaten our genomic integrity, namely double-strand breaks (DSBs). Fortunately, our cells have evolved with different repair mechanisms to deal with such lesions. There are two primary types of repair against DSBs: Homologous Recombination (HR) and Classical Non-Homologous End-Joining (CNHEJ). The HR pathway is an error-free repair mechanism used in the S-phase of the cell cycle to ensure faithful repair of the damaged area and thus preserve our genetic information. Individuals that bear mutations in proteins involved in this pathway, such as BRCA1 and BCRA2, have been associated with the development of breast and ovarian cancers. Almost 4 years ago, the field went through a major breakthrough in ovarian cancer care. A new class of drugs was accepted by the US Food and Drug Administration (FDA) to manage recurrent ovarian cancers that display HR-deficiencies. These drugs consist of inhibitor molecules against one of the earliest sensors of DNA damage in the cell: PARP-1 (poly(ADP-ribose) polymerase-1). Upon DNA damage induction, PARP-1 becomes highly activated, leading to the massive production of poly(ADP-ribose) (PAR) polymers, from the hydrolysis of nicotinamide adenine dinucleotide, which in turn modify several proteins posttranslationally and act as a scaffold to recruit DNA repair factors to the repair site. The successful application of PARP inhibitors (PARPi) arose from the observations that mutations or silencing of BRCA1/2, resulted in diminished HR activity. In the context of HR deficiency, the concomitant inhibition of PARP resulted in cell-death, an effect called synthetic lethality. Three PARPi are currently accepted by the FDA and are being clinically used for the treatment of gynaecological cancers. Notwithstanding the great promise of these inhibitors for other types of cancers, the mechanism by which these are inducing cancer lethality is not fully understood. Thus, it becomes of extreme importance to further decipher its mechanistic ways, to achieve full potential of PARPi in the clinic. To achieve this, fundamental research on the functions of PARPs and their protein partners in the DNA damage response is indispensable and constitutes the general aim of this thesis. During my doctoral work, we investigated the influence of PARP-1 during the HR pathway, primarily during the initial step of resection, which is essential for the removal of damaged DNA. Early reports of PARP-1 involvement in resection described the recruitment of the resection protein MRE11 to sites of damage in a PARP-1 dependent manner. Here, we demonstrate that PARP-1 has a novel function in DSB resection and we propose a new model for the synthetic lethality observed in HR-deficient tumors. To further complement the general aim of this doctorate, we investigated the regulatory roles of PARP-1 during the HR pathway, however in a later stage of HR resolution, at the peak formation of RAD51 foci, which is a crucial step for the efficient repair of DSBs through HR. We observed that the PAR-interactome (PARylome) at this stage was abundantly enriched with RNA-processing factors. Several of the most abundant proteins consisted of DNA and RNA helicases, as well as transcription factors, some of which were found to be mutated in tumors, and thus can be seen as potentially druggable targets to be used in combination with PARPi. We also extended our PARylome study to the chromatin proteome and investigated the histone PARylome upon DNA damage. Interestingly, we found that histone tails are not the only targets of PARP-1 and that globular domains are also targets of PARylation. Lastly, the high clinical interest of PARP-1 warrants studies addressing PARP-1 organ distribution. Thus, I finalized my studies by extensively describing and reporting PARP-1 tissular and cellular distribution and abundance in monkey organs, with the main objective of providing valuable information to any study assessing PARP inhibition efficacy and resistance in any given tissue and related diseases. In summary, this thesis provides important new information on the mechanisms PARP-1 is regulating during the response to DSBs, including the networks PARP-1 is orchestrating to potentially help reshape the cell environment, to efficiently repair the most lethal lesion our genome faces.

The economic impact of metallic corrosion on global infrastructure, spanning pipeline networks, bridges, refineries, and automobiles, is considerable. In 2013, it accounted for 3.4% of the global GDP, totaling US$ 2.5 trillion. Organic coatings have gained significance as a prominent strategy to address this widespread issue. Polyaniline (PANI), a conducting polymer, has long been recognized as an effective anti-corrosion coating. This study explores the potential of polyaniline analogs and their nanocomposites as candidates for protective organic coatings in corrosion control applications. Initially, the investigation focuses on conducting polymers with side chains comprising long, branched alkyl groups as potential corrosion suppression coatings. These polymers, containing carbazole, phenothiazine, and phenoxazine cores, serve as analogs to polyaniline. Prepared through the Buchwald/Hartwig coupling reaction, these polymers demonstrated promising corrosion suppression capabilities, as tested by potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS). Morphological characterization using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that phenothiazine- and carbazole-containing polymers exhibit excellent corrosion resistance, with phenothiazine displaying a protection efficiency (PE) of 95.9% and 89.0% respectively, outperforming polyaniline coating. Further exploration involved the derivatives of phenothiazine-based PANI analogs, specifically poly(heterocyclic diphenylamine) (poly-HDA), prepared through the Buchwald/Hartwig coupling reaction. Evaluation through weight loss, potentiodynamic polarization, and EIS in a 3.5 wt.% NaCl solution showcased the reduced corrosion current density on surfaces coated with long-branched alkyl-substituted phenothiazine-based PANI analogs. Moreover, the reinforcement of the phenothiazine-based PANI analog polymer was achieved by creating an epoxy-based nanocomposite with 2,5-dimethyl-1,4-phenylenediamine functionalized graphene oxide (PT/DPPD-fGO) at varying concentrations into an epoxy anticorrosive coating for AISI 4130 steel from corrosion. Results from immersion in 5 % sodium chloride solution, coupled with standard electrochemical measurements, demonstrate that PT/DPPD-fGO effectively protects AISI 4130 steel from corrosion, with coatings containing 5 % PT/DPPD-fGO exhibiting the best corrosion performance among the tested specimens. The results indicate the potential of phenothiazine- and carbazole-based PANI analogs, along with their nanocomposites, as candidates for protective organic coatings in transportation, aviation, marine, and oil and gas industrial applications.

Le cancer carcinoïde est une maladie rare caractérisée par des tumeurs neuroendocrines résistantes aux agents chimiothérapeutiques occasionnant un traitement difficile de celles-ci. Notre laboratoire travaille sur l'enzyme poly(ADP-ribose) polymérase-1 (PARP-1) impliquée dans différentes voies de réparation de l'ADN. La grande efficacité de ces voies est une des raisons pouvant expliquer la résistance observée des tumeurs neuroendocrines. Le but de ce projet était de déterminer le rôle de la PARP-1 dans le traitement du cancer carcinoïde par chimiothérapie. Nous avons obtenu un effet de potentialisation de la streptozotocine caractérisé par un ralentissement de la croissance cellulaire et de la réparation des dommages lors de l'inhibition de la PARP-1. D'un autre côté, nous avons constaté que le «knock down» de la PARP-1 résulte en une diminution du volume tumoral in vivo. Nos résultats montrent donc que la PARP-1 peut devenir une cible thérapeutique dans le traitement du cancer carcinoïde.