Traumatic spinal cord injury (SCI) is a devastating condition for which there is no effective clinical treatment. Neuroprotective molecules that minimize tissue loss have shown promising results; however systemic delivery may limit in vivo benefits due to short systemic half-life and minimal passage across the blood-spinal cord barrier. To overcome these limitations, an injectable intrathecal delivery vehicle comprised of hyaluronan and methylcellulose (HAMC) was developed, and previously demonstrated to be safe and biocompatible intrathecally. Here, HAMC was determined to persist in the intrathecal space for between 4-7 d in vivo, indicating it as an optimal delivery system for neuroprotective agents to reduce tissue degeneration after SCI. HAMC was then investigated as an in vivo delivery system for two neuroprotective proteins: erythropoietin (EPO) and fibroblast growth factor 2 (FGF2). Both proteins demonstrated a diffusive release profile in vitro and maintained significant bioactivity during release. When EPO was delivered intrathecally with HAMC to the injured spinal cord, reduced cavitation in the tissue and significantly improved neuron counts were observed relative to the conventional delivery strategies of intraperitoneal and intrathecal bolus. When FGF2 was delivered intrathecally from HAMC, therapeutic concentrations penetrated into the injured spinal cord tissue for up to 6 h. Poly(ethylene glycol) modification of FGF2 significantly increased the amount of protein that diffused into the tissue when delivered similarly. Because FGF2 is a known angiogenic agent, dynamic computed tomography was developed for small animal serial assessment of spinal cord hemodynamics. Following SCI and treatment with FGF2 from HAMC, moderate improvement of spinal cord blood flow and a reduction in permeability were observed up to 7 d post-injury, suggesting that early delivery of neuroprotective agents can have lasting effects on tissue recovery. Importantly, the entirety of this work demonstrates that HAMC is an effective short-term delivery system for neuroprotective agents by improving tissue outcomes following traumatic SCI.

Traumatic spinal cord injury (SCI) is a devastating condition for which there is no effective clinical treatment. Neuroprotective molecules that minimize tissue loss have shown promising results; however systemic delivery may limit in vivo benefits due to short systemic half-life and minimal passage across the blood-spinal cord barrier. To overcome these limitations, an injectable intrathecal delivery vehicle comprised of hyaluronan and methylcellulose (HAMC) was developed, and previously demonstrated to be safe and biocompatible intrathecally. Here, HAMC was determined to persist in the intrathecal space for between 4-7 d in vivo, indicating it as an optimal delivery system for neuroprotective agents to reduce tissue degeneration after SCI. HAMC was then investigated as an in vivo delivery system for two neuroprotective proteins: erythropoietin (EPO) and fibroblast growth factor 2 (FGF2). Both proteins demonstrated a diffusive release profile in vitro and maintained significant bioactivity during release. When EPO was delivered intrathecally with HAMC to the injured spinal cord, reduced cavitation in the tissue and significantly improved neuron counts were observed relative to the conventional delivery strategies of intraperitoneal and intrathecal bolus. When FGF2 was delivered intrathecally from HAMC, therapeutic concentrations penetrated into the injured spinal cord tissue for up to 6 h. Poly(ethylene glycol) modification of FGF2 significantly increased the amount of protein that diffused into the tissue when delivered similarly. Because FGF2 is a known angiogenic agent, dynamic computed tomography was developed for small animal serial assessment of spinal cord hemodynamics. Following SCI and treatment with FGF2 from HAMC, moderate improvement of spinal cord blood flow and a reduction in permeability were observed up to 7 d post-injury, suggesting that early delivery of neuroprotective agents can have lasting effects on tissue recovery. Importantly, the entirety of this work demonstrates that HAMC is an effective short-term delivery system for neuroprotective agents by improving tissue outcomes following traumatic SCI.

<p>Nanofabrication techniques were used to manufacture nanometer scale protein templates. The fabrication approach employs electron beam lithography (EBL) patterning on poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) self-assembled monolayers (SAM) on Au. The PEG SAM prevented protein surface adhesion and binding sites for protein were created in the SAM by EBL. Subsequent to EBL, the patterns in the PEG SAM were backfilled with 40-nm NeutrAvidin-coated fluorescent spheres (FluoSpheres). The spontaneous and directed immobilization of the spheres from a solution to the patterns resulted in high resolution protein patterns. The FluoSpheres could be arranged in any arbitrary pattern with ultimately only one or a few FluoSpheres at each binding site.</p><p>Growth dynamics and SAM morphology of PEG on Au were studied by atomic force microscopy (AFM). PEG SAMs on three types of Au with different microstructure were examined: thermally evaporated granular Au and two types of Au films produced by hydrogen flame annealing of granular Au, Au(111) and "terraced" Au (crystal orientation unknown). The different Au surfaces' substructure affected the morphology and mechanical properties of the PEG SAM. On Au(111), AFM imaging revealed monolayer formation through three distinct steps: island nucleation, island growth, and coalescence. The fine-structure of the SAM revealed dendritic island formation - an observation which can be explained by attractive intermolecular interactions and diffusion-limited aggregation. Island growth was not observed on the "terraced" Au.</p><p>AFM studies of EBL patterned PEG SAMs on Au(111) revealed two different patterning mechanisms. At low doses, the pattern formation occurs by SAM ablation in a self-developing process where the feature depth is directly dose dependent. At higher doses electron beam induced deposition of material, so-called contamination writing, is seen in the ablated areas of the SAM. The balance between these two mechanisms is shown to depend on the geometry of the pattern.</p><p>In addition to PEG SAMs, fibronectin monolayers on SiO2 surfaces were patterned by EBL. The areas exposed with EBL lose their functionality and do not bind anti-fibronectin. With this approach we constructed fibronectin templates and used them for cell studies demonstrating pattern dependent cell geometries and cell adhesion.</p>

Biodegradable hydrogels have become very promising materials for a number of biomedical applications, including tissue engineering and drug delivery. For optimal tissue engineering design, the mechanical properties of hydrogels should match those of native tissues as closely as possible because these properties are known to affect the behavior and function of cells seeded in the hydrogels. At the same time, high water-contents, large mesh sizes and well-tuned degradation rates are favorable for the controlled release of growth factors and for adequate transport of nutrients through the hydrogel during tissue regeneration. With these factors in mind, the goal of this research was to develop and investigate the behavior of injectable, biodegradable hydrogels with enhanced stiffness properties that persist even at high degrees of swelling. In order to do this, degradable functionalities were incorporated into photo-crosslinkable poly(ethylene glycol) and poly(acrylic acid) hydrogels, and these two components were used to make a series of double-network hydrogels. Synthesis of the precursor macromers, photopolymerization of the hydrogels, and structural parameters of the hydrogels were analyzed. The composition and the molecular weight between crosslinks (Mc) of the hydrogel components were varied, and the degradation, swelling, thermal and mechanical properties of the hydrogels were characterized over various time scales. These properties were compared to corresponding properties of the component single-network hydrogels.

The aim of this study was to investigate the impact of the casein microstructure on the molecular diffusion of probes with different sizes and deformabilities. The mobility of molecular flexible ('PEG') and rigid (dendrimer) probes of various sizes was studied in suspensions and gels of NPC and SC at various protein concentrations. Measurements were carried out by NMR, which makes it possible to probe translational mobilities over a distance of 1.5 microns, as well as local mobilities at the molecular scale (several nanometers) through the relaxation times, T2. A coherent model was used and the same mechanism was proposed to describe the diffusion of small probes in both casein dispersions. It is the combination of different factors that should be considered: the ratio of the probe size to the distance between the obstructing particles or the entanglement points, as well as the flexibility of the probe. The rotational diffusion of PEG and dendrimer probes was less hindered than translational diffusion in both casein systems. Different relaxation behaviors were observed between the two casein systems and retardation in T2 relaxation times was highlighted in rennet and acid casein gels. These results are probably related to the local mobility of the matrix. The overall results of this project led to a better understanding of probe mobility in casein systems and made it possible to propose a new model that challenges the previous one proposed by Le Feunteun et al. to describe the diffusion of probes in casein systems.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Entre os polímeros considerados promissores para a remoção seletiva de CO2, destacam-se aqueles que contêm os grupos glicol etilênico (EG). Nesta dissertação, foram obtidos filmes a partir de dispersões aquosas de poliuretano (PU), sintetizadas em trabalho anterior, à base de poli(glicol propilênico) (PPG), copolímero em bloco à base de poli(glicol etilênico) (PEG) e PPG (EG-b-PG), ácido dimetilolpropiônico (DMPA), diisocianato de isoforona (IPDI) e etilenodiamina (EDA). PPG, EG-b-PG e DMPA formaram as regiões flexíveis nas proporções de: PPG 100% e 0% EG-b-PG, PPG 75% e 25% EG-b-PG, PPG 50% e 50% EG-b-PG e PPG 25% e 75% EG-b-PG em termos de equivalentes-gramas. A influência da quantidade dos segmentos de PEG foi avaliada por ensaios de permeação com os gases CO2, CH4 e N2. Os filmes obtidos das dispersões foram caracterizados por espectrometria de infravermelho com transformadas de Fourier (FTIR), análise termogravimétrica (TGA), difração de raios x (DRX) e espalhamento de raios X a baixo ângulo (SAXS). Espectros de FTIR mostraram que os segmentos de EG influenciaram a frequência da banda de carbonila. Curvas de perda de massa (TG) mostraram perfis semelhantes de degradação, enquanto que as curvas derivadas apresentaram diferenças. DRX e SAXS mostraram que os segmentos de PEG promoveram uma maior ordenação na estrutura da membrana. Testes de permeação de gases mostraram que o aumento do teor de PEG aumentou o valor da permeabilidade para o CO2, indicando que os segmentos de PEG interagiram favoravelmente com este gás. Em relação ao CH4 e N2, houve uma diminuição na permeabilidade quando comparados com os valores encontrados para o CO2, sendo atribuído a perda de mobilidade segmental. Em termos de seletividade, para o par CO2/CH4 foi obtido um valor médio de 61,7 para a membrana contendo o maior teor de PEG, e o par CO2/N2 um valor médio de 121,5, sendo superior aos valores encontrados na literatura, tornando o material promissor / Among the polymers considered promising for the selective removal of CO2 from natural gas, those containing ethylene glycol groups (EG) are the most distinguished. In this study cast films were obtained from aqueous dispersions of polyurethane (PU), synthesized in a previous work with poly (propylene glycol) (PPG), block copolymer based on poly(ethylene glycol) (PEG) and PPG, dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and ethylenediamine (EDA). Segments of PPG, EG-b-PG and DMPA formed the flexible domains in the proportions of: PPG 100% and 0% EG-b-PG, PPG 75% and 25% EG-b-PG, PPG 50% and 50% EG-b-PG and PPG 25% and 75% EG-b-PG, in terms of equivalent-grams. The influence of the amount of PEG segments in permeation properties of CO2, CH4 and N2 was verified by permeability essays. The membranes were obtained as cast films from the dispersions and was characterized by infrared spectrometry (FTIR), termogravimetric analysis (TGA), X ray diffractometry (XRD) and small angle X ray scattering (SAXS). FTIR spectra showed that PEG segments influenced carbonyl band frequency. Loss of mass curves with temperature (TG) showed similar profiles of degradation, whereas DTG curves presented more stages. PEG segments conferred higher thermal stability for the materials. XRD and SAXS analysis showed that PEG promoted ordination to the membranes. In gas permeation tests, it was verified that the increase in copolymer amount increased permeability value for CO2, being attributed to the fact that the segments of poly(ethylene glycol) interacted favorably with this gas. In relation to CH4 and N2, there was a significant decrease in permeability when compared to the values found for CO2, being assigned to a loss of segmental mobility with increasing content of EG. In terms of selectivity, the pair CO2/CH4 had a mean value of 61,7 for the membrane containing the highest amount of EG groups, and the pair CO2/N2 produced a mean value of 121,5 for the same one, being superior than those found in the literature, making a promising material

Made available in DSpace on 2016-12-08T17:19:34Z (GMT). No. of bitstreams: 1 Pre-textuais.pdf: 74879 bytes, checksum: 6785c5543c0fdea74eb42ad4be2cded6 (MD5) Previous issue date: 2009-12-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Multi-wall carbon nanotubes (MWNT) functionalized with poly(ethylene glycol) (PEG) were used to prepare epoxy matrix nanocomposites based on Bisphenol A Diglycidyl Ether (DGEBA), in order to evaluate the effect of functionalization in nanotubes/matrix dispersion and adhesion. Firstly, two works were carried out to estimate the reaction between DGEBA and PEG using sulfuric acid (H2SO4) or dimethylbenzylamine (DMBA), as catalysts, aiming the evaluation of viable routes to reaction of PEG chains connected to nanotubes with epoxy resin. The reaction product was analyzed with infrared spectroscopy (FTIR), proton magnetic resonance spectroscopy (RMN) and viscosity. The results confirmed the reaction occurs between DGEBA epoxy groups and PEG hydroxyl groups in the presence of dimethylbenzylamine as catalyst at 100°C. DSC analyses and tensile tests of cured hardener systems based on polyamine show that the DGEBA reaction with PEG leads to a decrease of Tg, originating a more flexible material. Epoxy matrix nanocomposites were prepared using 0,1% m/m of NCPM functionalized with PEG and 0,5% m/m of dimethylbenzylamine. The samples were characterized with infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). It was observed through SEM images a better adhesion of NCPM-PEG with matrix, in comparison with pristine MWNT, suggesting that NCPM-PEG reacted with the epoxy resin DGEBA. DSC analysis showed a Tg value decrease to prepared nanocomposites when compared to pure epoxy resin. / Nanotubos de carbono de paredes múltiplas (NCPM) funcionalizados com poli(etilenoglicol) (PEG), foram usados na preparação de nanocompósitos de matriz epóxi a base de diglicidil éter de bisfenol A (DGEBA), para avaliar o efeito da funcionalização na dispersão e adesão do nanotubo na matriz. Primeiramente dois estudos foram realizados para avaliar a reação entre DGEBA e PEG, utilizando ácido sulfúrico (H2SO4) ou dimetilbenzilamina (DMBA) como catalisadores, com o objetivo de se avaliar uma rota viável para a reação das cadeias de PEG ligadas aos nanotubos com a resina epóxi. O produto da reação foi avaliado por espectroscopia no infravermelho (FTIR), espectroscopia de ressonância magnética nuclear (RMN) de 1H e viscosidade. Os resultados das análises confirmaram a ocorrência da reação entre grupos epóxi do DGEBA e grupos hidroxila do PEG na presença de dimetilbenzilamina como catalisador, a 100°C. Análises de DSC e ensaios de tração dos sistemas curados com endurecedor a base de poliamina mostram que a reação de DGEBA com PEG leva a uma diminuição da Tg, gerando um material mais flexível. Nanocompósitos de matriz epóxi foram preparados usando 0,1% m/m de NCPM funcionalizados com PEG e catalisador dimetilbenzilamina na quantidade de 0,5% m/m. As amostras obtidas foram caracterizadas por Espectroscopia na região do Infravermelho (FTIR), Calorimetria Exploratória Diferencial (DSC), Análise termogravimétrica (TG), Microscopia Eletrônica de Varredura (MEV) e Análise dinâmico-mecânica (DMA). Através das imagens obtidas por MEV, sugere-se uma maior adesão dos NCPM-PEG com a matriz, indicando que os NCPM-PEG reagiram com a resina epóxi à base de DGEBA. Análises de DSC mostraram uma diminuição do valor da Tg para os nanocompósitos preparados quando comparados a resina epóxi pura.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Entre os polímeros considerados promissores para a remoção seletiva de CO2, destacam-se aqueles que contêm os grupos glicol etilênico (EG). Nesta dissertação, foram obtidos filmes a partir de dispersões aquosas de poliuretano (PU), sintetizadas em trabalho anterior, à base de poli(glicol propilênico) (PPG), copolímero em bloco à base de poli(glicol etilênico) (PEG) e PPG (EG-b-PG), ácido dimetilolpropiônico (DMPA), diisocianato de isoforona (IPDI) e etilenodiamina (EDA). PPG, EG-b-PG e DMPA formaram as regiões flexíveis nas proporções de: PPG 100% e 0% EG-b-PG, PPG 75% e 25% EG-b-PG, PPG 50% e 50% EG-b-PG e PPG 25% e 75% EG-b-PG em termos de equivalentes-gramas. A influência da quantidade dos segmentos de PEG foi avaliada por ensaios de permeação com os gases CO2, CH4 e N2. Os filmes obtidos das dispersões foram caracterizados por espectrometria de infravermelho com transformadas de Fourier (FTIR), análise termogravimétrica (TGA), difração de raios x (DRX) e espalhamento de raios X a baixo ângulo (SAXS). Espectros de FTIR mostraram que os segmentos de EG influenciaram a frequência da banda de carbonila. Curvas de perda de massa (TG) mostraram perfis semelhantes de degradação, enquanto que as curvas derivadas apresentaram diferenças. DRX e SAXS mostraram que os segmentos de PEG promoveram uma maior ordenação na estrutura da membrana. Testes de permeação de gases mostraram que o aumento do teor de PEG aumentou o valor da permeabilidade para o CO2, indicando que os segmentos de PEG interagiram favoravelmente com este gás. Em relação ao CH4 e N2, houve uma diminuição na permeabilidade quando comparados com os valores encontrados para o CO2, sendo atribuído a perda de mobilidade segmental. Em termos de seletividade, para o par CO2/CH4 foi obtido um valor médio de 61,7 para a membrana contendo o maior teor de PEG, e o par CO2/N2 um valor médio de 121,5, sendo superior aos valores encontrados na literatura, tornando o material promissor / Among the polymers considered promising for the selective removal of CO2 from natural gas, those containing ethylene glycol groups (EG) are the most distinguished. In this study cast films were obtained from aqueous dispersions of polyurethane (PU), synthesized in a previous work with poly (propylene glycol) (PPG), block copolymer based on poly(ethylene glycol) (PEG) and PPG, dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and ethylenediamine (EDA). Segments of PPG, EG-b-PG and DMPA formed the flexible domains in the proportions of: PPG 100% and 0% EG-b-PG, PPG 75% and 25% EG-b-PG, PPG 50% and 50% EG-b-PG and PPG 25% and 75% EG-b-PG, in terms of equivalent-grams. The influence of the amount of PEG segments in permeation properties of CO2, CH4 and N2 was verified by permeability essays. The membranes were obtained as cast films from the dispersions and was characterized by infrared spectrometry (FTIR), termogravimetric analysis (TGA), X ray diffractometry (XRD) and small angle X ray scattering (SAXS). FTIR spectra showed that PEG segments influenced carbonyl band frequency. Loss of mass curves with temperature (TG) showed similar profiles of degradation, whereas DTG curves presented more stages. PEG segments conferred higher thermal stability for the materials. XRD and SAXS analysis showed that PEG promoted ordination to the membranes. In gas permeation tests, it was verified that the increase in copolymer amount increased permeability value for CO2, being attributed to the fact that the segments of poly(ethylene glycol) interacted favorably with this gas. In relation to CH4 and N2, there was a significant decrease in permeability when compared to the values found for CO2, being assigned to a loss of segmental mobility with increasing content of EG. In terms of selectivity, the pair CO2/CH4 had a mean value of 61,7 for the membrane containing the highest amount of EG groups, and the pair CO2/N2 produced a mean value of 121,5 for the same one, being superior than those found in the literature, making a promising material

La catalyse, les solvants alternatifs et l'économie d'atome font partie des clés pour le développement de nouvelles stratégies durables de synthèse. Des hétérocycles comme les quinoléines substituées, par réaction de cycloisomérisation catalysée par le cuivre en utilisant les liquides ioniques, et les isoquinoléines carbonylées par réaction de carbonylation oxydante catalysée par le palladium dans le méthanol ont été synthétisées. La formation sélective de 1,3-dihydroisobenzofuranes et/ou 1H-isochromènes a été tentée par réaction de cycloisomérisation catalysée par différent métaux de transition. La synthèse d'hétérocycles à cinq chaînons, par exemple furanes, pyrroles et pyrrolin-4-ones à été mise au point par nouvelle réaction de cycloisomérisation catalysée par de sels de platine ou d'or en utilisant des diols, des amino alcools ou des α-amino-ynones dans le PEG sous activation micro-ondes. Les produits sont récupérés pur après une simple étape de précipitation-filtration. Les α-amino-ynones chiral sont synthétisée à partir de N-protégé carboxyanhydrides des aminoacides (UNCAs). Une réaction de iodocyclisation a été aussi développée pour obtenir de nouvelles structures hétérocycliques. / Catalysis, alternative solvents and atom economy represent key areas for the sustainable development of versatile strategies in organic chemistry. Fused heterocycles, such as substituted quinolines by a cycloisomerization reaction using a recyclable catalytic system copper/ionic liquids and isoquinoline-4-carboxylic esters based on PdI2-catalyzed oxidative carbonylation were prepared. A selective 5-exo-dig or 6-endo-dig cyclization route to obtain 1,3-dihydroisobenzofurans and/or 1H-isochromenes was tested by metal transition cycloisomerization reaction of alkynylbenzyl alcohols in PEG. Five membered ring heterocycles such as furans, pyrroles and pyrrolin-4-ones were successfully obtained by a novel platinum or gold-catalyzed cycloisomerization reaction of diols, aminoalcohols or α-amino-ynones in poly(ethylene glycol) (PEG) under microwave irradiation. The heterocyclic systems were recovered pure after a simple precipitation-filtration work-up. The catalytic systems were studied by using the TEM and XPS techniques. The chiral α-amino-ynone substrates were prepared by an original method starting from N-protected carboxyanhydrides of amino acids (UNCAs). Also unprecedented results are reported in the area of iodocyclization to obtain chiral iodopyrrolin-ones.

Le fascinant processus par lequel les signaux mécaniques sont transformés en réactions biochimiques dans la nature est appelé mécano-transduction. Le but de ma thèse a été de mimer la Nature en élaborant de nouveaux systèmes enzymatiques mécano-transductifs, i.e des matériaux capables de moduler une catalyse enzymatique lorsqu’ils sont sollicités mécaniquement. Nous avons d’abord étudié l’effet de l’étirement sur les chaînes constitutives de films multicouches de polyélectrolytes, matrices souvent utilisées pour le développement de biomatériaux intelligents. Dans le cadre d’une nouvelle stratégie axée sur la modulation mécanique de la conformation, nous avons ensuite élaboré des matrices étirables à base de poly(éthylène glycol)s. Nous avons en particulier développé de tout nouveaux revêtements covalents appelés nanogels qui se sont avérés être déposables sur le silicone étirable et fonctionnalisables avec différentes biomacromolécules, ouvrant ainsi de nouvelles routes biomimétiques. / The fascinating process by which mechanical signals are transformed into biochemical reactions in Nature is called mechanotransduction. The goal of my PhD was to mimic Nature by elaborating new types of mechanocatalytic materials, i.e materials able to modulate a catalytic activity when mechanically stimulated. We first aimed at understanding the impact of stretching on the structural properties of polyelectrolyte multilayers films, polymeric matrices often used for the design of smart biomaterials. Within the framework of a new strategy essentially relying on mechanically induced conformational changes, we then developed stretchable polymeric matrices based on poly(ethylene glycol)s. We more particularly designed new types of covalent coatings, called nanogels. We showed that these architectures were buildable on stretchable silicone and that they could be functionalized with different types of biomacromolecules; thus opening new biomimetic routes.