L'ingénierie tissulaire du ligament constitue une approche prometteuse pour réparer ou remplacer un ligament endommagé. Les trois piliers essentiels de l'ingénierie tissulaire ligamentaire sont la matrice de support (aussi appelée scaffold), la source cellulaire, ainsi que l'apport de stimulations biomécaniques/biochimiques : ces trois piliers ont été partiellement étudiés par le passé dans le but de s’orienter vers une régénération ligamentaire. Dans la présente étude, le polymère synthétique poly (L-lactide-co-ε-caprolactone) (PLCL) et la soie ont été proposés et comparés comme de potentiels candidats pour la constitution d’une matrice de support. Une série de matrices tressées multicouches à base de PLCL et de soie, ainsi qu'un nouveau composite soie/PLCL ont été développés et comparés. Les caractérisations physico-chimiques et biologiques ont démontré que le PLCL et la soie constituent des candidats pertinents, tant sur les plans mécaniques que biologiques, pour la constitution d’une matrice de support. De plus, nous avons montré que le composite soie/PLCL offrait des propriétés mécaniques et une biocompatibilité accrue par rapport aux autres matrice testées, et constituait probablement le candidat le plus approprié pour l'ingénierie tissulaire du ligament. Les cellules souches mésenchymateuses (CSM) de la gelée de Wharton (WJ-MSCs) ainsi que les cellules souches mésenchymateuses de la moelle osseuse (BM-MSCs) ont été évaluées et comparées en tant que sources cellulaires potentielles pour la régénération ligamentaire. Les caractéristiques biologiques de ces cellules incluent l’adhésion cellulaire, la prolifération, la migration et la synthèse de matrice extracellulaire. Ces deux types de cellules ont montré une bonne biocompatibilité dans leurs interactions avec les matrices de support en PLCL et en soie. Aucune différence significative n'a été observée entre les WJ-MSCs et les BM-MSCs. Enfin, l'effet de la stimulation biomécanique sur la différentiation des CSM en tissu ligamentaire a été évalué par le biais d’un bioréacteur de traction-torsion. Bien que peu de cellules aient été détectées la matrice après 7 jours de stimulation, des CSM de forme allongée le long des fibres ont été détectées, ce qui permet de penser qu'il est possible de promouvoir la différenciation des biosubstituts matrice-cellules grâce à la stimulation mécanique en bioréacteur. En conclusion, cette étude démontre le potentiel prometteur de l’association de cellules souches mésenchymateuses issues de la gelée de Wharton ou de la moelle osseuse avec une matrice de support composite soie/PLCL pour la régénération ligamentaire dans le futur. / Ligament tissue engineering offers a potential approach to recover or replace injured ligament. The three essential elements that have been investigated towards ligament regeneration consist in a suitable scaffold, an adapted cell source, and the supply of biomechanical/biochemical stimulations. In the current study, synthetic polymer poly (L-lactide-co-ε-caprolactone) (PLCL) and silk have been evaluated as suitable candidates to constitute an adapted scaffold. A series of multilayer braided scaffolds based on PLCL and silk, as well as an original silk/PLCL composite scaffold, have been developed and compared. The conducted physicochemical and biological characterizations have demonstrated that both PLCL and silk constitute adapted candidate material to form ligament scaffolds from the mechanical and biological points of view. Moreover, it has been observed that silk/PLCL composite scaffold resulted in adequate mechanical properties and biocompatibility, and therefore could constitute suitable candidate scaffolds for ligament tissue engineering. Both Wharton’s Jelly mesenchymal stem cells (WJ-MSCs) and Bone marrow mesenchymal stem cells (BM-MSCs) have been evaluated to be cell source for ligament regeneration. MSCs behaviors including cell attachment, proliferation, migration and extracellular matrix synthesis have been investigated. In the present study, both MSCS showed a good biocompatibility to interact with PLCL and silk scaffolds. No significant differences have been detected between WJ-MSCs and BM-MSCs. Finally, the effect of biomechanical stimulation on MSCs differentiation towards ligament tissue has been carried out with a tension-torsion bioreactor. Although few cells were detected on scaffold after 7 days of stimulation, MSCs were observed to exhibit an elongated shape along the longitudinal direction of fibers, which may indicate that an adapted mechanical stimulation could promote MSC-scaffold constructs differentiation towards ligamentous tissue. As a conclusion, this study demonstrates the potential of WJ-MSCs and BM-MSCs combined with a new silk/PLCL composite scaffold towards ligament regeneration.

Degradable polymers have gained an increased attention in the field of biomedical applications over the past decades, for example in tissue engineering. One way of improving the biocompatibility of these polymers is by chemical surface modification, however the risk of degradation during the modification procedure is a limiting factor. In some biomedical applications, for example in nerve guides, a patterned surface is desired to improve the cell attachment and proliferation. In this thesis a new non-destructive, single-step, and solvent free method for surface modification of degradable polymers is described. Poly(L-lactide) (PLLA) substrates have been functionalized with one of the following vinyl monomers; N-vinylpyrrolidone (VP), acrylamide (AAm), or maleic anhydride (MAH) grafts. The substrates were subjected to a vapor phase atmosphere constituted of a mixture of a vinyl monomer and a photoinitiator (benzophenone) in a closed chamber at very low pressure and under UV irradiation. Poly(ε-caprolactone) (PCL), poly(lactide-co-glycolide) (PLGA), and poly(trimethylene carbonate) (PTMC) have been surface modified with VP using the same procedure to show the versatility of the method. The wettability of all of the four substrates increased after grafting. The surface compositions were confirmed by ATR-FTIR and XPS. The VP grafted PLLA, PTMC and PLGA substrates have been shown to be good substrates for the normal human cells i.e. keratinocytes and fibroblasts, to adhere and proliferate on. The topography of substrates with well defined nano patterns was preserved during grafting, since the grafted layer is very thin. We have also shown that the method is useful for a simultaneous chemical and topographical modification of substrates by masked vapor phase grafting. The surface topography was determined with SEM and AFM. / Intresset för användningen av nedbrytbara polymerer till biomedicinska applikationer som till exempel vävnads rekonstruktion har ökat avsevärt de senaste decennierna. Ett sätt att öka biokompatibiliteten hos dessa polymerer är genom kemisk ytmodifiering, men risken för nedbrytning under själva modifieringen är en begränsande faktor. I vissa biomedicinska applikationer, till exempel nervguider, är det önskvärt att ha en väldefinierad ytstruktur för att öka vidhäftningen och tillväxten av celler. I den här avhandlingen presenteras en ny ickeförstörande, lösningsmedelsfri enstegsprocess för ytmodifiering av nedbrytbara polymerer. Substrat av poly(L-laktid) (PLLA) har ytfunktionaliserats med var och en av följande vinylmonomerer, N-vinylpyrrolidon (VP), akrylamid (AAm) eller maleinsyraanhydrid (MAH). Substraten har exponerats för en gasfasatmosfär av en blandning av en vinylmonomer och en fotoinitiator (bensofenon) i en tillsluten reaktor vid mycket lågt tryck och under UV-strålning. Metodens mångsidighet har även påvisats genom att ytmodifiera substrat av poly(ε-kaprolakton) (PCL), poly(laktid-co-glykolid) (PLGA) och poly(trimetylen karbonat) (PTMC) med VP. Vätbarheten ökade för alla fyra materialen efter ympning med en vinylmonomer. Ytsammansättningen fastställdes med ATR-FTIR och XPS. De VP ympade filmerna av PLLA, PLGA och PTMC visade sig vara bra substrat för mänskliga celler, i detta fall keratinocyter och fibroblaster, att vidhäfta och växa på. Yttopografin hos filmer med väldefinierade nanomönstrade ytor kunde bevaras efter ympning, tack vare att det ympade lagret är så tunt. Gasfas metoden har också visat sig användbar för att simultant ytmodifiera både kemiskt och topografiskt genom maskad gasfasympning. Yttopografin bestämdes med SEM och AFM. / QC 20101014

Résumé: Dans le but de préparer des complexes de Zr pour la catalyse homogène de la polymérisation des lactides et de l’hydroamination des olefines, l’elaboration et l’optimisation d’une méthode systématique et efficace de synthèse des ligands dikétimines ayant différents substituants alkyles (R) à la position N,N’ a été realisée. Des dikétimines (nacnacRH) symétriques ont été obtenus avec une pureté de plus de 95 % et un rendement de 65 % lorsque R = Me et des rendements allant de 80 à 95 % lorsque le groupe R = n-Pr, i-Pr, i-Bu, Bu, Cy et (+)-CH(Me)Ph. La synthèse des dikétimines ayant des substituants N-alkyls différents, dite asymétriques, donne toujours un mélange statistique de trois ligands: nacnacR,R’H, nacnacR,RH et nacnacR’,R’H qui n’ont pu être separés. Seuls les dikétimines asymétriques avec un substituant N-alkyl et un autre N-aryl (nacnacR,ArH) ont été obtenus avec des rendements plus élevés que celui du mélange statistique. Par la suite, la complexation de ces ligands bidentés au Zr, la caractérisation de ces complexes et l’investigation de la réactivité ont été étudiés. Les complexes de Zr de type (nacnacR)2ZrCl2 ont été obtenus par deux voies de synthèse principales: la première consiste à traiter le sel de lithium du ligand avec le ZrCl4. La seconde est la réaction du ligand avec les complexes neutres d’alkyl-zirconium(IV) par protonation de l'alkyle coordonné. En solution, les complexes obtenus de (nacnacR)2ZrX2 possèdent un comportement dynamique via un « Bailar-twist » et les paramètres d'activation de cette isomérisation ont été calculés. Le complexe octaèdrique (nacnacBn)2ZrCl2 n'est pas réactif dans la carbozirconation et son alkylation n'était pas possible par l’échange des chlorures avec les alkyles. L’analogue diméthylé (nacnacBn)2ZrMe2 peut être préparé par alkylation du ZrCl4 avant la complexation du ligand. On a également observé que ce dernier n’est pas réactif dans la carbozirconation. L‘analogue diéthoxyde (nacnacBn)2Zr(OEt)2 est obtenu par échange des diméthyles avec les éthoxydes. La polymérisation du lactide avec celui-ci en tant que précurseur est relativement lente et ne peut être effectuée que dans le monomère fondu. Par conséquent, pour résoudre les problèmes rencontrés avec les complexes de zirconium (dikétiminates non-pontés), un ligand dikétimines pontés par le diaminocyclohexane, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-diméthylphényle) a été préparé. La complexation de ce ligand tetradenté au metal a été réalisée par deux voies de synthèse; la première est la réaction du sel de lithium de ce ligand avec le ZrCl4(THF)2. La deuxième est la déprotonation du ligand neutre avec le Zr(NMe2)4 et l’élimination du diméthylamine. Des complexes du type: (±)-C6H10(nacnacXylH)2ZrX2 avec X = Cl, NMe2 ont été obtenus. Les ligands de chlorure sont dans ce cas facilement remplaçables par des éthoxydes ou des méthyles. On a observé l’activité la plus élevée jamais observée pour un complexe d’un métal du groupe 4 avec le complexe de (±)-C6H10(nacnacXylH)2Zr(OEt)2 dans la polymérisation de lactide. L'étude cinétique a montré que la loi de vitesse est du premier ordre en catalyseur et en monomère et la constante de vitesse est k = 14 (1) L mol-1 s-1. L'analyse des polymères a montré l’obtention de masses moléculaires faibles et l’abscence de stéréocontrôle. La réaction de (±)-C6H10(nacnacXylH)2ZrCl2 avec le triflate d’argent donne le (±)-C6H10(nacnacXylH)2Zr(OTf)2. Le complexe bis-triflate obtenu possède une activité catalytique elevée pour les additions du type aza-Michael. L’utilisation du R,R-C6H10(nacnacXylH)2Zr(OTf)2 énantiopur comme catalyseur, dans les additions du type aza-Michael asymétriques donne le produit desiré avec un excès énantiomérique de 19%. / Abstract: In order to prepare the complexes of Zr targeted for homogeneous catalysis in polymerization of lactides and hydroamination of activated olefins, we focused on the elaboration and the optimization of a systematic and efficient method for the synthesis of diketimines ligands with a variety of substituted alkyl (R) on their position N,N'. Symmetrical diketimines (nacnacRH) were obtained with a greater than 95% purity and a yield of 65% when R = Me and yields ranging from 80 to 95% when R = nPr, iPr, iBu, Bn, and Cy (+)-CH (Me) Ph. The Synthesis of diketimines with different N-alkyl substituents, called asymmetric, always gives a statistical mixture of three ligands: nacnacR,R'H nacnacR,RH and nacnacR',R'H that made their isolation problematic. Yields greater than statistical mixtures were obtained only with asymmetric diketimines bearing N-alky and N-aryl substituents (nacnacR,ArH). Subsequently, we studied the complexation of these bidentate ligands with Zr, the characterization of these complexes and investigation of their reactivity. Zr complexes of type (nacnacRH)2ZrCl2 were obtained via two main synthetic routes: the first consists in treatment of the lithium salt of the ligand with ZrCl4. The second is the reaction of the ligand with neutral complexes of alkyl-zirconium (IV) by protonation of the alkyl coordinated. In solution, the obtained complexes (nacnacR)2ZrX2 showed dynamic behavior via a "Bailar-twist" isomerization and the activation parameters of the isomerization were calculated. Octahedral complex (nacnacBn)2ZrCl2, showed no reactivity in alkylation and carbozirconation was not possible by the exchange of alkyl with chlorides. The dimethyl analogue (nacnacBn)2ZrMe2, can be prepared by alkylation of ZrCl4 before ligand complexing. The diethoxide analogue (nacnacBn)2Zr(OEt)2 is obtained by exchange of dimethyls with ethoxides. The latter had slow reactivity in lactide polymerization under melt conditions. Consequently, to address the problems encountered with unbridged (diketiminate) zirconium complexes, a cyclohexanediyl-bridged diketiminate ligand, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-dimethylphenyl) is prepared. Complexation of the tetradentate ligand is realized via two synthetic routes; The first is reaction of the lithium salt of the ligand with ZrCl4(THF)2. The second is deprotonation of the neutral ligand with Zr(NMe2)4 and elimination of dimethylamine. Complexes of the type: (±)-C6H10(nacnacXylH)2ZrX2 with X = Cl, NMe2 are obtained. The chloride ligands are in this case readily replaceable with ethoxides or methyls. The (±)-C6H10(nacnacXylH)2Zr(OEt)2 complex showed the highest activity ever observed for any group 4 metal complex in lactide polymerization. The kinetic study showed that the rate law is first order in catalyst and monomer and the rate constant is k = 14(1) L mol−1 s−1. Analysis of the obtained polymer showed low molecular weight with no-stereocontrol. Reaction of the (±)-C6H10(nacnacXylH)2ZrCl2 with silver triflates yielded the (±)-C6H10(nacnacXylH)2Zr(OTf)2. The obtained bis-triflate complex showed to be a highly active catalyst for aza-Michael additions. The use of the enatiopure R,R-C6H10(nacnacXyl)2Zr(OTf)2 as catalyst for asymmetric aza-Michael additions of activated olefines gave the desired product with an enantiomeric excess of 19%.

This Thesis describes the synthesis and characterisation of new Main Group and Rare Earth alkyl, amide, alkoxide and borohydride complexes and their use as catalysts for the ring-opening polymerisation (ROP) of &epsilon;-caprolactone and rac-lactide. <strong>Chapter 1</strong> introduces ROP from an industrial and academic perspective, as well as polymer characterisation techniques. A literature review is given, with an emphasis placed on Main Group catalysts. <strong>Chapter 2</strong> describes the synthesis and characterisation of new homo- and hetero-scorpionate Main Group complexes. An introduction to homo- and hetero-scorpionate ligands is given, as well as a discussion of the ε-caprolactone and rac-lactide ROP activity displayed by the new complexes. <strong>Chapter 3</strong> describes the synthesis and characterisation of new neutral and cationic Main Group borohydride complexes supported by the tris(pyrazolyl)methane and tris(pyrazolyl)hydroborate ligands. A review of borohydride complexes is also given. The ε-caprolactone and rac-lactide ROP activity shown by the complexes presented is also discussed. <strong>Chapter 4</strong> describes the synthesis and characterisation of new mono- and di-cationic yttrium complexes supported by the tris(pyrazolyl)methane and triazacyclononane ligands. An introduction to the synthesis of neutral and cationic Rare Earth complexes is given. An overview of immortal ROP is also provided. The activity of the new complexes towards the immortal ROP of rac-lactide is also discussed. <strong>Chapter 5</strong> contains experimental details and characterising data for the new complexes reported in this thesis. CD Appendix</strong> contains .cif files for all of the new crystallographically characterised complexes.

Résumé: Dans le but de préparer des complexes de Zr pour la catalyse homogène de la polymérisation des lactides et de l’hydroamination des olefines, l’elaboration et l’optimisation d’une méthode systématique et efficace de synthèse des ligands dikétimines ayant différents substituants alkyles (R) à la position N,N’ a été realisée. Des dikétimines (nacnacRH) symétriques ont été obtenus avec une pureté de plus de 95 % et un rendement de 65 % lorsque R = Me et des rendements allant de 80 à 95 % lorsque le groupe R = n-Pr, i-Pr, i-Bu, Bu, Cy et (+)-CH(Me)Ph. La synthèse des dikétimines ayant des substituants N-alkyls différents, dite asymétriques, donne toujours un mélange statistique de trois ligands: nacnacR,R’H, nacnacR,RH et nacnacR’,R’H qui n’ont pu être separés. Seuls les dikétimines asymétriques avec un substituant N-alkyl et un autre N-aryl (nacnacR,ArH) ont été obtenus avec des rendements plus élevés que celui du mélange statistique. Par la suite, la complexation de ces ligands bidentés au Zr, la caractérisation de ces complexes et l’investigation de la réactivité ont été étudiés. Les complexes de Zr de type (nacnacR)2ZrCl2 ont été obtenus par deux voies de synthèse principales: la première consiste à traiter le sel de lithium du ligand avec le ZrCl4. La seconde est la réaction du ligand avec les complexes neutres d’alkyl-zirconium(IV) par protonation de l'alkyle coordonné. En solution, les complexes obtenus de (nacnacR)2ZrX2 possèdent un comportement dynamique via un « Bailar-twist » et les paramètres d'activation de cette isomérisation ont été calculés. Le complexe octaèdrique (nacnacBn)2ZrCl2 n'est pas réactif dans la carbozirconation et son alkylation n'était pas possible par l’échange des chlorures avec les alkyles. L’analogue diméthylé (nacnacBn)2ZrMe2 peut être préparé par alkylation du ZrCl4 avant la complexation du ligand. On a également observé que ce dernier n’est pas réactif dans la carbozirconation. L‘analogue diéthoxyde (nacnacBn)2Zr(OEt)2 est obtenu par échange des diméthyles avec les éthoxydes. La polymérisation du lactide avec celui-ci en tant que précurseur est relativement lente et ne peut être effectuée que dans le monomère fondu. Par conséquent, pour résoudre les problèmes rencontrés avec les complexes de zirconium (dikétiminates non-pontés), un ligand dikétimines pontés par le diaminocyclohexane, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-diméthylphényle) a été préparé. La complexation de ce ligand tetradenté au metal a été réalisée par deux voies de synthèse; la première est la réaction du sel de lithium de ce ligand avec le ZrCl4(THF)2. La deuxième est la déprotonation du ligand neutre avec le Zr(NMe2)4 et l’élimination du diméthylamine. Des complexes du type: (±)-C6H10(nacnacXylH)2ZrX2 avec X = Cl, NMe2 ont été obtenus. Les ligands de chlorure sont dans ce cas facilement remplaçables par des éthoxydes ou des méthyles. On a observé l’activité la plus élevée jamais observée pour un complexe d’un métal du groupe 4 avec le complexe de (±)-C6H10(nacnacXylH)2Zr(OEt)2 dans la polymérisation de lactide. L'étude cinétique a montré que la loi de vitesse est du premier ordre en catalyseur et en monomère et la constante de vitesse est k = 14 (1) L mol-1 s-1. L'analyse des polymères a montré l’obtention de masses moléculaires faibles et l’abscence de stéréocontrôle. La réaction de (±)-C6H10(nacnacXylH)2ZrCl2 avec le triflate d’argent donne le (±)-C6H10(nacnacXylH)2Zr(OTf)2. Le complexe bis-triflate obtenu possède une activité catalytique elevée pour les additions du type aza-Michael. L’utilisation du R,R-C6H10(nacnacXylH)2Zr(OTf)2 énantiopur comme catalyseur, dans les additions du type aza-Michael asymétriques donne le produit desiré avec un excès énantiomérique de 19%. / Abstract: In order to prepare the complexes of Zr targeted for homogeneous catalysis in polymerization of lactides and hydroamination of activated olefins, we focused on the elaboration and the optimization of a systematic and efficient method for the synthesis of diketimines ligands with a variety of substituted alkyl (R) on their position N,N'. Symmetrical diketimines (nacnacRH) were obtained with a greater than 95% purity and a yield of 65% when R = Me and yields ranging from 80 to 95% when R = nPr, iPr, iBu, Bn, and Cy (+)-CH (Me) Ph. The Synthesis of diketimines with different N-alkyl substituents, called asymmetric, always gives a statistical mixture of three ligands: nacnacR,R'H nacnacR,RH and nacnacR',R'H that made their isolation problematic. Yields greater than statistical mixtures were obtained only with asymmetric diketimines bearing N-alky and N-aryl substituents (nacnacR,ArH). Subsequently, we studied the complexation of these bidentate ligands with Zr, the characterization of these complexes and investigation of their reactivity. Zr complexes of type (nacnacRH)2ZrCl2 were obtained via two main synthetic routes: the first consists in treatment of the lithium salt of the ligand with ZrCl4. The second is the reaction of the ligand with neutral complexes of alkyl-zirconium (IV) by protonation of the alkyl coordinated. In solution, the obtained complexes (nacnacR)2ZrX2 showed dynamic behavior via a "Bailar-twist" isomerization and the activation parameters of the isomerization were calculated. Octahedral complex (nacnacBn)2ZrCl2, showed no reactivity in alkylation and carbozirconation was not possible by the exchange of alkyl with chlorides. The dimethyl analogue (nacnacBn)2ZrMe2, can be prepared by alkylation of ZrCl4 before ligand complexing. The diethoxide analogue (nacnacBn)2Zr(OEt)2 is obtained by exchange of dimethyls with ethoxides. The latter had slow reactivity in lactide polymerization under melt conditions. Consequently, to address the problems encountered with unbridged (diketiminate) zirconium complexes, a cyclohexanediyl-bridged diketiminate ligand, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-dimethylphenyl) is prepared. Complexation of the tetradentate ligand is realized via two synthetic routes; The first is reaction of the lithium salt of the ligand with ZrCl4(THF)2. The second is deprotonation of the neutral ligand with Zr(NMe2)4 and elimination of dimethylamine. Complexes of the type: (±)-C6H10(nacnacXylH)2ZrX2 with X = Cl, NMe2 are obtained. The chloride ligands are in this case readily replaceable with ethoxides or methyls. The (±)-C6H10(nacnacXylH)2Zr(OEt)2 complex showed the highest activity ever observed for any group 4 metal complex in lactide polymerization. The kinetic study showed that the rate law is first order in catalyst and monomer and the rate constant is k = 14(1) L mol−1 s−1. Analysis of the obtained polymer showed low molecular weight with no-stereocontrol. Reaction of the (±)-C6H10(nacnacXylH)2ZrCl2 with silver triflates yielded the (±)-C6H10(nacnacXylH)2Zr(OTf)2. The obtained bis-triflate complex showed to be a highly active catalyst for aza-Michael additions. The use of the enatiopure R,R-C6H10(nacnacXyl)2Zr(OTf)2 as catalyst for asymmetric aza-Michael additions of activated olefines gave the desired product with an enantiomeric excess of 19%.

Atualmente, existe uma grande necessidade médica por enxertos vasculares de pequeno calibre (< 6 mm), que possam ser utilizados em cirurgias de reconstrução vascular. Nesse trabalho, dois tipos de biomateriais vasculares foram desenvolvidos pela técnica de electrospinning: biomateriais de policaprolactona (PCL) e biomateriais de poli(carbonato de trimetileno – co – ácido lático) (PTMCLLA). Os biomateriais de PCL foram funcionalizados com heparina e com VEGF (PCL/Hep/VEGF). Os biomateriais de PTMCLLA foram desenvolvidos a partir de três razões de carbonato de trimetileno/ ácido lático: 20/80, 30/70 e 40/60. Os biomateriais de PCL apresentaram taxa de degradação lenta e alta elasticidade. A funcionalização dos biomateriais preveniu a coagulação do sangue e também favoreceu o crescimento de células-tronco mesenquimais (CTMs) e de células progenitoras endoteliais (CPEs) nessas estruturas. A análise de PCR demonstrou que o VEGF adsorvido aos biomateriais não foi suficiente para diferenciar as CTMs em células endoteliais. O cultivo das CPEs sobre os biomateriais aumentou a expressão de VE-caderina e a presença de VEGF nas estruturas manteve o nível de expressão de CD31 e CD34 nessas células. Após essas análises, os biomateriais de PCL/Hep/VEGF foram fabricados em formato tubular. As CPEs foram semeadas no lúmen do biomaterial, através de biorreatores de parede rotatória (BPR), e mantidas em cultivo, por biorreatores de perfusão (BP). O BPR favoreceu a distribuição homogênea das CPEs na parede luminal dos biomateriais enquanto que o BP estimulou seu crescimento e otimizou seu metabolismo energético. Os biomateriais produzidos a partir dos copolímeros de PTMCLLA 30/70 e 40/60 exibiram uma alta flexibilidade. Porém, os biomateriais de PTMCLLA 40/60 tiveram um grande enrugamento. Os biomateriais de PTMCLLA 30/70 suportaram a adesão e o crescimento de CTMs, de CPEs e de células musculares lisas. Os resultados obtidos no presente estudo demonstram que biomateriais de PCL/Hep/VEGF apresentam características físico-químicas compatíveis para o uso vascular. Ainda, previnem a formação de trombos em sua superfície e propiciam o desenvolvimento da camada endotelial em seu lúmen. Os biomateriais de PTMCLLA 30/70 exibem alta flexibilidade e suportam o desenvolvimento de células vasculares e de células-tronco mesenquimais. De acordo com esses resultados, é possível concluir que biomateriais de PCL/Hep/VEGF e de PTMCLLA 30/70 são candidatos promissores para aplicação como enxertos vasculares. / Currently, there is a great medical need for small caliber vascular grafts (<6 mm), which can be used in vascular replacement surgeries. In this work, two types of vascular biomaterials were developed by the electrospinning technique: biomaterials of polycaprolactone (PCL) and biomaterials of poly(trimethylene carbonate-co-L-lactide) (PTMCLLA). PCL biomaterials were functionalized with heparin and VEGF (PCL / Hep/VEGF). The PTMCLLA biomaterials were developed from three ratios of trimethylene carbonate/lactide: 20/80, 30/70 and 40/60. The PCL biomaterials presented a slow degradation rate and high elasticity. The functionalization of the biomaterials prevented the blood from clotting and also favored the growth of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) in these structures. PCR analysis demonstrated that VEGF adsorbed by the biomaterials was not sufficient to differentiate the MSCs into endothelial cells. The cultivation of CPEs on the biomaterials increased their expression of VE-cadherin and the presence of VEGF in the structures maintained the cell expression of CD34 and CD31. After these analyzes, the PCL/Hep/VEGF biomaterials were produced in a tubular geometrical form. The CPEs were seeded into their lumen by rotating bioreactors (RB) and maintained in culture by perfusion bioreactors (PB). The RB favored the homogeneous distribution of the CPEs in the luminal wall of the biomaterials while the BP stimulated their growth and optimized their energetic metabolism. The biomaterials produced from the PTMCLLA 30/70 and 40/60 copolymers exhibited high flexibility. However, the PTMCLLA 40/60 biomaterials exhibited substantial wrinkling. The PTMCLLA 30/70 biomaterials supported the adhesion and growth of MSCs, CPEs and smooth muscle cells. This study has demonstrated that PCL/Hep/VEGF biomaterials have physicochemical characteristics compatible with vascular use. Furthermore, they prevent thrombus formation on their surfaces and promote the development of the endothelial layer in their lumen. Biomaterials of PTMCLLA 30/70 exhibit high flexibility and support the development of vascular and mesenchymal stem cells. According to these results, it can be concluded that PCL/Hep/VEGF and PTMCLLA 30/70 biomaterials are promising candidates for use as vascular grafts.

Synthetic and degradable polymers are an attractive choicein many areas, since it is possible to control the way in whichthey are manufactured; more specifically, pathways tomanipulate the architecture, the mechanical properties and thedegradation times have been identified. In this work,L-lactide, 1,5-dioxepan-2-one and ε-caprolactone were usedas monomers to synthesize polymers with different architecturesby ring-opening polymerization. By using novel initiators,triblock copolymers, functionalized linear macromonomers andstar-shaped aliphatic polyesters with well-defined structureshave been synthesized. To synthesize triblock copolymers,cyclic germanium initiators were studied. The polymerizationproceeded in a controlled manner although the reaction rateswere low. To introduce functionality into the polymer backbone,functionalized cyclic tin alkoxides were prepared and used asinitiators. During the insertion-coordination polymerization,the initiator fragment consisting mainly of a double bond wasincorporated into the polymer backbone. The double bond wasalso successfully epoxidized and this gave unique possibilitiesof synthesizing graft polymers with precise spacing. Themacromonomer technique is a very effective method for producingwell-defined graft polymers. Spirocyclic tin initiators weresynthesized and used to construct star-shaped polymers. Thestar-shaped polymers were subsequently crosslinked in apolycondensation reaction. These crosslinked structures swelledin water, and swelling tests showed that by changing thestructure of the hydrogel network, the degree of swelling canbe altered. A first evaluation of the surface characteristicsof the linear triblock copolymers was also performed. AFManalysis of the heat-treated surfaces revealed nanometer-scalefibers and tests showed that keratinocytes were able to growand proliferate on these surfaces. / QC 20100602

The aim of this thesis is the investigation of modeling and optimization particularities of tubular polymerization reactors. The original work is divided in two sections, the first treating a modeling and optimization study of tubular reactors for methyl methacrylate polymerization in solution, and the second, an experimental and theoretical study of L-lactide reactive extrusion. In the first section, reactor simulations in similar operating conditions were performed in order to select a representative kinetic model among the published kinetic models for MMA solution polymerization. Two widely used numerical algorithms, one based on Pontryagin's Minimum Principle and the other a Genetic Algorithm, were compared for an average-complexity optimization problem. The results showed a superior robustness of the Genetic Algorithm for this category of problems. The second part of the thesis deals with the modeling and optimization of L-lactide reactive extrusion. A kinetic model is proposed and its parameters estimated using nonlinear estimation numerical procedures based on experimentally measured data. Reactive extrusion experiments were performed in representative operating conditions. The Llactide/ polylactide flow in the extruder was characterized by simulation using the commercial software LUDOVIC®. The simulated residence time distributions characteristics are used to model the reactive extrusion process of two approaches, an axial dispersion model and a compartment model, based on compartments whose characteristics are deduced from the simulations using LUDOVIC®. The modeling results are in good agreement with the measured data in the same operating conditions.

Atualmente, existe uma grande necessidade médica por enxertos vasculares de pequeno calibre (< 6 mm), que possam ser utilizados em cirurgias de reconstrução vascular. Nesse trabalho, dois tipos de biomateriais vasculares foram desenvolvidos pela técnica de electrospinning: biomateriais de policaprolactona (PCL) e biomateriais de poli(carbonato de trimetileno – co – ácido lático) (PTMCLLA). Os biomateriais de PCL foram funcionalizados com heparina e com VEGF (PCL/Hep/VEGF). Os biomateriais de PTMCLLA foram desenvolvidos a partir de três razões de carbonato de trimetileno/ ácido lático: 20/80, 30/70 e 40/60. Os biomateriais de PCL apresentaram taxa de degradação lenta e alta elasticidade. A funcionalização dos biomateriais preveniu a coagulação do sangue e também favoreceu o crescimento de células-tronco mesenquimais (CTMs) e de células progenitoras endoteliais (CPEs) nessas estruturas. A análise de PCR demonstrou que o VEGF adsorvido aos biomateriais não foi suficiente para diferenciar as CTMs em células endoteliais. O cultivo das CPEs sobre os biomateriais aumentou a expressão de VE-caderina e a presença de VEGF nas estruturas manteve o nível de expressão de CD31 e CD34 nessas células. Após essas análises, os biomateriais de PCL/Hep/VEGF foram fabricados em formato tubular. As CPEs foram semeadas no lúmen do biomaterial, através de biorreatores de parede rotatória (BPR), e mantidas em cultivo, por biorreatores de perfusão (BP). O BPR favoreceu a distribuição homogênea das CPEs na parede luminal dos biomateriais enquanto que o BP estimulou seu crescimento e otimizou seu metabolismo energético. Os biomateriais produzidos a partir dos copolímeros de PTMCLLA 30/70 e 40/60 exibiram uma alta flexibilidade. Porém, os biomateriais de PTMCLLA 40/60 tiveram um grande enrugamento. Os biomateriais de PTMCLLA 30/70 suportaram a adesão e o crescimento de CTMs, de CPEs e de células musculares lisas. Os resultados obtidos no presente estudo demonstram que biomateriais de PCL/Hep/VEGF apresentam características físico-químicas compatíveis para o uso vascular. Ainda, previnem a formação de trombos em sua superfície e propiciam o desenvolvimento da camada endotelial em seu lúmen. Os biomateriais de PTMCLLA 30/70 exibem alta flexibilidade e suportam o desenvolvimento de células vasculares e de células-tronco mesenquimais. De acordo com esses resultados, é possível concluir que biomateriais de PCL/Hep/VEGF e de PTMCLLA 30/70 são candidatos promissores para aplicação como enxertos vasculares. / Currently, there is a great medical need for small caliber vascular grafts (<6 mm), which can be used in vascular replacement surgeries. In this work, two types of vascular biomaterials were developed by the electrospinning technique: biomaterials of polycaprolactone (PCL) and biomaterials of poly(trimethylene carbonate-co-L-lactide) (PTMCLLA). PCL biomaterials were functionalized with heparin and VEGF (PCL / Hep/VEGF). The PTMCLLA biomaterials were developed from three ratios of trimethylene carbonate/lactide: 20/80, 30/70 and 40/60. The PCL biomaterials presented a slow degradation rate and high elasticity. The functionalization of the biomaterials prevented the blood from clotting and also favored the growth of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) in these structures. PCR analysis demonstrated that VEGF adsorbed by the biomaterials was not sufficient to differentiate the MSCs into endothelial cells. The cultivation of CPEs on the biomaterials increased their expression of VE-cadherin and the presence of VEGF in the structures maintained the cell expression of CD34 and CD31. After these analyzes, the PCL/Hep/VEGF biomaterials were produced in a tubular geometrical form. The CPEs were seeded into their lumen by rotating bioreactors (RB) and maintained in culture by perfusion bioreactors (PB). The RB favored the homogeneous distribution of the CPEs in the luminal wall of the biomaterials while the BP stimulated their growth and optimized their energetic metabolism. The biomaterials produced from the PTMCLLA 30/70 and 40/60 copolymers exhibited high flexibility. However, the PTMCLLA 40/60 biomaterials exhibited substantial wrinkling. The PTMCLLA 30/70 biomaterials supported the adhesion and growth of MSCs, CPEs and smooth muscle cells. This study has demonstrated that PCL/Hep/VEGF biomaterials have physicochemical characteristics compatible with vascular use. Furthermore, they prevent thrombus formation on their surfaces and promote the development of the endothelial layer in their lumen. Biomaterials of PTMCLLA 30/70 exhibit high flexibility and support the development of vascular and mesenchymal stem cells. According to these results, it can be concluded that PCL/Hep/VEGF and PTMCLLA 30/70 biomaterials are promising candidates for use as vascular grafts.

Atualmente, existe uma grande necessidade médica por enxertos vasculares de pequeno calibre (< 6 mm), que possam ser utilizados em cirurgias de reconstrução vascular. Nesse trabalho, dois tipos de biomateriais vasculares foram desenvolvidos pela técnica de electrospinning: biomateriais de policaprolactona (PCL) e biomateriais de poli(carbonato de trimetileno – co – ácido lático) (PTMCLLA). Os biomateriais de PCL foram funcionalizados com heparina e com VEGF (PCL/Hep/VEGF). Os biomateriais de PTMCLLA foram desenvolvidos a partir de três razões de carbonato de trimetileno/ ácido lático: 20/80, 30/70 e 40/60. Os biomateriais de PCL apresentaram taxa de degradação lenta e alta elasticidade. A funcionalização dos biomateriais preveniu a coagulação do sangue e também favoreceu o crescimento de células-tronco mesenquimais (CTMs) e de células progenitoras endoteliais (CPEs) nessas estruturas. A análise de PCR demonstrou que o VEGF adsorvido aos biomateriais não foi suficiente para diferenciar as CTMs em células endoteliais. O cultivo das CPEs sobre os biomateriais aumentou a expressão de VE-caderina e a presença de VEGF nas estruturas manteve o nível de expressão de CD31 e CD34 nessas células. Após essas análises, os biomateriais de PCL/Hep/VEGF foram fabricados em formato tubular. As CPEs foram semeadas no lúmen do biomaterial, através de biorreatores de parede rotatória (BPR), e mantidas em cultivo, por biorreatores de perfusão (BP). O BPR favoreceu a distribuição homogênea das CPEs na parede luminal dos biomateriais enquanto que o BP estimulou seu crescimento e otimizou seu metabolismo energético. Os biomateriais produzidos a partir dos copolímeros de PTMCLLA 30/70 e 40/60 exibiram uma alta flexibilidade. Porém, os biomateriais de PTMCLLA 40/60 tiveram um grande enrugamento. Os biomateriais de PTMCLLA 30/70 suportaram a adesão e o crescimento de CTMs, de CPEs e de células musculares lisas. Os resultados obtidos no presente estudo demonstram que biomateriais de PCL/Hep/VEGF apresentam características físico-químicas compatíveis para o uso vascular. Ainda, previnem a formação de trombos em sua superfície e propiciam o desenvolvimento da camada endotelial em seu lúmen. Os biomateriais de PTMCLLA 30/70 exibem alta flexibilidade e suportam o desenvolvimento de células vasculares e de células-tronco mesenquimais. De acordo com esses resultados, é possível concluir que biomateriais de PCL/Hep/VEGF e de PTMCLLA 30/70 são candidatos promissores para aplicação como enxertos vasculares. / Currently, there is a great medical need for small caliber vascular grafts (<6 mm), which can be used in vascular replacement surgeries. In this work, two types of vascular biomaterials were developed by the electrospinning technique: biomaterials of polycaprolactone (PCL) and biomaterials of poly(trimethylene carbonate-co-L-lactide) (PTMCLLA). PCL biomaterials were functionalized with heparin and VEGF (PCL / Hep/VEGF). The PTMCLLA biomaterials were developed from three ratios of trimethylene carbonate/lactide: 20/80, 30/70 and 40/60. The PCL biomaterials presented a slow degradation rate and high elasticity. The functionalization of the biomaterials prevented the blood from clotting and also favored the growth of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) in these structures. PCR analysis demonstrated that VEGF adsorbed by the biomaterials was not sufficient to differentiate the MSCs into endothelial cells. The cultivation of CPEs on the biomaterials increased their expression of VE-cadherin and the presence of VEGF in the structures maintained the cell expression of CD34 and CD31. After these analyzes, the PCL/Hep/VEGF biomaterials were produced in a tubular geometrical form. The CPEs were seeded into their lumen by rotating bioreactors (RB) and maintained in culture by perfusion bioreactors (PB). The RB favored the homogeneous distribution of the CPEs in the luminal wall of the biomaterials while the BP stimulated their growth and optimized their energetic metabolism. The biomaterials produced from the PTMCLLA 30/70 and 40/60 copolymers exhibited high flexibility. However, the PTMCLLA 40/60 biomaterials exhibited substantial wrinkling. The PTMCLLA 30/70 biomaterials supported the adhesion and growth of MSCs, CPEs and smooth muscle cells. This study has demonstrated that PCL/Hep/VEGF biomaterials have physicochemical characteristics compatible with vascular use. Furthermore, they prevent thrombus formation on their surfaces and promote the development of the endothelial layer in their lumen. Biomaterials of PTMCLLA 30/70 exhibit high flexibility and support the development of vascular and mesenchymal stem cells. According to these results, it can be concluded that PCL/Hep/VEGF and PTMCLLA 30/70 biomaterials are promising candidates for use as vascular grafts.