The freshwater planarian has a great capacity to regenerate and is an ideal animal model in the study of stem cell and regeneration biology. In this study planarian regenerating new tails were exposed to nonlethal doses of Betadine®, Polyvinylpyrrolidone (PVP), and Iodine. Betadine® is a topical antiseptic commonly used in the healthcare setting and may have a detrimental effect on wound healing. PVP is linked to iodine to create povidone-iodine, the active ingredient in Betadine®. Initially, a preliminary test was performed on the worms to determine the nonlethal concentrations of these chemicals . After this nonlethal concentration was determined, tails were amputated and a designated number of worms were placed in the Betadine®, PVP, and Iodine solutions. Spring water was used as a control. This study determined that Betadine® and PVP showed no significant impact on regrowth rate and wound healing in the planarian, while Iodine did.

Made available in DSpace on 2014-10-09T12:26:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:12Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Amanda Silva (amanda.osilva2@ufpe.br) on 2015-04-07T13:44:32Z No. of bitstreams: 2 DISSERTAÇÃO Sheila de Melo Barros.pdf: 1291445 bytes, checksum: db27132996d617b0597281f66a66672b (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-04-07T13:44:32Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Sheila de Melo Barros.pdf: 1291445 bytes, checksum: db27132996d617b0597281f66a66672b (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-02-29 / CAPES / Atualmente, um grande número de técnicas encontra-se disponível para a caracterização de polímeros sintéticos, tais como a cromatografia por exclusão molecular (CEM), ressonância magnética nuclear (RMN) e técnicas de caracterização por massa como a ionização/dessorção a laser assistida por matiz (MALDI-TOF). Para a maioria dos polímeros sintéticos com elevada polidispersidade, no entanto, estas técnicas necessitam de outros métodos complementares ou de um tratamento prévio da amostra. Recentemente, foi demostrado que poros de α-hemolisina podem ser usados como um espectrômetro de massas em solução para moléculas de polietilenoglicol (PEG), baseado na interação entre um poro de escala nanométrica e moléculas do analito, onde moléculas poliméricas de diferentes tamanhos no interior do nanoporo promovem diferentes estados de condutância com média característica dos tempos de residência. Neste trabalho a interação entre a Polivinilpirrolidona (PVP) e canais de α-hemolisina na presença de elevada corrente iônica foi utilizada para o desenvolvimento de um novo modelo de espectrômetro de massas para polímeros em espaço confinado, baseado em poros de escala nanométrica. Em nossos experimentos, foi utilizada uma solução banhante de (4M KCl, Tris 5 mM, pH 7,5) e uma amostra polidispersa de PVP de peso médio de 10KDa como analito polimérico. A confecção da bicamada lipídica plana e a inserção do nanoporo unitário na membrana, bem como os registros de correntes iônicas através dos poros, foram obtidos em condições de fixação de voltagem. Os resultados demonstram que poros de α-HL são capazes de detectar a polidispersidade do PVP e discriminar as cadeias moleculares com diferentes tamanhos. Os resultados obtidos com o nanoporo sensor apresentaram dados similares aos obtidos nas análises com o MALDI-TOF convencional. Fornecendo as bases científicas para o desenvolvimento de um espectrômetro de massas a partir do canal unitário uma caracterização em tempo real de polímeros sintéticos em solução.

Hidrogéis compreendem uma importante classe de materiais poliméricos adequados à aplicação como curativos de feridas e queimaduras. A estrutura tridimensional hidrofílica dos hidrogéis permite que estes mantenham a umidade ideal no leito das feridas, absorvam o exsudato e não causem danos ao novo tecido durante as trocas dos curativos. No caso dos hidrogéis, essas trocas podem ser menos frequentes. Além disso, curativos que auxiliem na remoção de tecidos necrosados e ainda sejam capazes de oferecer tratamentos extras que acelerem o processo de cicatrização são desejáveis. Este trabalho apresenta a produção de materiais à base de hidrogel capazes de auxiliar neste processo de diferentes maneiras. Primeiramente, são apresentados hidrogéis formados a partir de nanofibras de poli(N-vinil-2-pirrolidona) (PVP) produzidas por eletrofiação, seguido da reticulação através da utilização de radiação UV-C ou reação de Fenton. A utilização da eletrofiação como técnica auxiliar na formação dos hidrogéis permitiu o controle da porosidade através da formação de fibras de diferentes diâmetros. A evidência de tal propriedade foi constatada através da produção de materiais que apresentam diferentes perfis de liberação da proteína modelo albumina de soro bovino (BSA). O hidrogel de PVP nanoestruturado foi capaz de liberar e manter a atividade da colagenase, uma importante enzima aplicada no tratamento de feridas via desbridamento enzimático, durante as 48 horas em que foi avaliado. Além disso, hidrogéis bactericidas nanoestruturados foram produzidos a partir de nanocompósitos de PVP e nanopartículas de prata (AgNP) produzidos por eletrofiação. Esses hidrogéis apresentaram propriedades térmicas semelhantes aos hidrogéis sem AgNP, diminuindo, contudo, a sua capacidade de intumescimento. Esses hidrogéis mostraram-se ativos contra bactérias gram-positivas e gram-negativas a partir de 100 ppm de AgNPs. Adicionalmente, foi estudada a formação de um hidrogel modelo composto PVP/AgNP/Imidazol, almejando-se a produção de um material bactericida-fungicida a base de hidrogel. Este hidrogel apresentou atividade conta três espécies de Candida a partir de 500 ppm de imidazol no material. Embora exista a formação de um complexo estável entre AgNP e Imidazol, cálculos teóricos e a constatação da atividade fungicida corroboram com o fato de que derivados imidazólicos podem ser liberados a partir deste hidrogel híbrido. A produção de hidrogéis físicos compostos por blendas de PVP/Polianidridos sintetizados a partir de derivados de hidroxicinamatos e ácido salicílico, capazes de liberar moléculas de interesse biológico quando parcialmente degradados hidroliticamente, também é descrita neste trabalho. Os resultados indicam que interações hidrofóbicas entre a PVP e os polianidridos sintetizados podem ser responsáveis pela formação dos hidrogéis físicos e pela miscibilidade das blendas produzidas. Os hidrogéis físicos de PVP/Polianidridos foram obtidos na forma de filmes por evaporação do solvente. Micro- e nanofibras também foram obtidas por eletrofiação. Desta maneira, o presente trabalho contribui com o desenvolvimento de uma geração de curativos multifuncionais aplicados no tratamento de feridas crônicas e queimaduras. / Hydrogels comprise an important class of polymeric materials that finds application as wound and burn dressings. The hydrophilic three-dimensional structure of hydrogels helps to provide the ideal humidity at the wound bed, to remove exsudates and to prevent damages to the new tissue during dressing substitution. Furthermore, these wound dressings are able to remove necrotic tissues and, therefore, capable to offer extra treatments that would benefit the healing processes. This work describes the production of hydrogel based materials that are able to act in wound healing by different ways. First, it is presented hydrogels composed of poly(N-vinyl-2-pyrrolidone) (PVP) nanofibers produced by electrospinning, followed by its crosslinking using UV-C radiation or Fenton reaction. The use of electrospinning in the hydrogel formation allowed porosity control by obtaining fibers of different diameters. This was evidenced by achieving materials that present different release profiles of the model protein bovine serum albumin (BSA). The nanostructured PVP hydrogel was capable of releasing and maintaining collagenase activity during 48 hour of evaluation. This is an important enzyme that find application in wound healing based on enzymatic debridement. Moreover, nanostructured bactericidal hydrogels were produced from PVP and silver nanoparticles (AgNP) composite through electrospinning, resulting in hydrogels with thermal properties similar to those hydrogels without AgNP, decreasing its swelling ability. These hydrogels were active against gram-positives and gram-negatives bacteria starting from 100 ppm of AgNP. In addition, the production of a model hydrogel composed by PVP/AgNP/Imidazole was investigated, aiming at a bactericidal-fungicidal hydrogel based material. This hydrogel was active against three Candida having 500 ppm of imidazole into the structure. In spite of the formation of a stable complex between AgNP and imidazole, theoretic calculations and the observed fungicidal activity corroborate with the fact that imidazoles derivatives can be released from this hybrid hydrogel. Physical hydrogels composed of PVP/Polyanhydrides blends were synthesized from hydroxycinammates derivatives and salicylic acid. These materials which were capable of releasing molecules with biological potential upon hydrolysis, are also described in this work. The results indicate that hydrophobic interactions between PVP and the synthesized polyanhydrides could be responsible for the hydrogel formation and blend miscibility as well. PVP/Polyanhydride physical hydrogels were obtained from cast films. Micro- and nanofibers were also obtained by electrospinning. Thus, the present work contributes with the development of the new generation of smart dressings for wound and burn healing.

Hidrogéis compreendem uma importante classe de materiais poliméricos adequados à aplicação como curativos de feridas e queimaduras. A estrutura tridimensional hidrofílica dos hidrogéis permite que estes mantenham a umidade ideal no leito das feridas, absorvam o exsudato e não causem danos ao novo tecido durante as trocas dos curativos. No caso dos hidrogéis, essas trocas podem ser menos frequentes. Além disso, curativos que auxiliem na remoção de tecidos necrosados e ainda sejam capazes de oferecer tratamentos extras que acelerem o processo de cicatrização são desejáveis. Este trabalho apresenta a produção de materiais à base de hidrogel capazes de auxiliar neste processo de diferentes maneiras. Primeiramente, são apresentados hidrogéis formados a partir de nanofibras de poli(N-vinil-2-pirrolidona) (PVP) produzidas por eletrofiação, seguido da reticulação através da utilização de radiação UV-C ou reação de Fenton. A utilização da eletrofiação como técnica auxiliar na formação dos hidrogéis permitiu o controle da porosidade através da formação de fibras de diferentes diâmetros. A evidência de tal propriedade foi constatada através da produção de materiais que apresentam diferentes perfis de liberação da proteína modelo albumina de soro bovino (BSA). O hidrogel de PVP nanoestruturado foi capaz de liberar e manter a atividade da colagenase, uma importante enzima aplicada no tratamento de feridas via desbridamento enzimático, durante as 48 horas em que foi avaliado. Além disso, hidrogéis bactericidas nanoestruturados foram produzidos a partir de nanocompósitos de PVP e nanopartículas de prata (AgNP) produzidos por eletrofiação. Esses hidrogéis apresentaram propriedades térmicas semelhantes aos hidrogéis sem AgNP, diminuindo, contudo, a sua capacidade de intumescimento. Esses hidrogéis mostraram-se ativos contra bactérias gram-positivas e gram-negativas a partir de 100 ppm de AgNPs. Adicionalmente, foi estudada a formação de um hidrogel modelo composto PVP/AgNP/Imidazol, almejando-se a produção de um material bactericida-fungicida a base de hidrogel. Este hidrogel apresentou atividade conta três espécies de Candida a partir de 500 ppm de imidazol no material. Embora exista a formação de um complexo estável entre AgNP e Imidazol, cálculos teóricos e a constatação da atividade fungicida corroboram com o fato de que derivados imidazólicos podem ser liberados a partir deste hidrogel híbrido. A produção de hidrogéis físicos compostos por blendas de PVP/Polianidridos sintetizados a partir de derivados de hidroxicinamatos e ácido salicílico, capazes de liberar moléculas de interesse biológico quando parcialmente degradados hidroliticamente, também é descrita neste trabalho. Os resultados indicam que interações hidrofóbicas entre a PVP e os polianidridos sintetizados podem ser responsáveis pela formação dos hidrogéis físicos e pela miscibilidade das blendas produzidas. Os hidrogéis físicos de PVP/Polianidridos foram obtidos na forma de filmes por evaporação do solvente. Micro- e nanofibras também foram obtidas por eletrofiação. Desta maneira, o presente trabalho contribui com o desenvolvimento de uma geração de curativos multifuncionais aplicados no tratamento de feridas crônicas e queimaduras. / Hydrogels comprise an important class of polymeric materials that finds application as wound and burn dressings. The hydrophilic three-dimensional structure of hydrogels helps to provide the ideal humidity at the wound bed, to remove exsudates and to prevent damages to the new tissue during dressing substitution. Furthermore, these wound dressings are able to remove necrotic tissues and, therefore, capable to offer extra treatments that would benefit the healing processes. This work describes the production of hydrogel based materials that are able to act in wound healing by different ways. First, it is presented hydrogels composed of poly(N-vinyl-2-pyrrolidone) (PVP) nanofibers produced by electrospinning, followed by its crosslinking using UV-C radiation or Fenton reaction. The use of electrospinning in the hydrogel formation allowed porosity control by obtaining fibers of different diameters. This was evidenced by achieving materials that present different release profiles of the model protein bovine serum albumin (BSA). The nanostructured PVP hydrogel was capable of releasing and maintaining collagenase activity during 48 hour of evaluation. This is an important enzyme that find application in wound healing based on enzymatic debridement. Moreover, nanostructured bactericidal hydrogels were produced from PVP and silver nanoparticles (AgNP) composite through electrospinning, resulting in hydrogels with thermal properties similar to those hydrogels without AgNP, decreasing its swelling ability. These hydrogels were active against gram-positives and gram-negatives bacteria starting from 100 ppm of AgNP. In addition, the production of a model hydrogel composed by PVP/AgNP/Imidazole was investigated, aiming at a bactericidal-fungicidal hydrogel based material. This hydrogel was active against three Candida having 500 ppm of imidazole into the structure. In spite of the formation of a stable complex between AgNP and imidazole, theoretic calculations and the observed fungicidal activity corroborate with the fact that imidazoles derivatives can be released from this hybrid hydrogel. Physical hydrogels composed of PVP/Polyanhydrides blends were synthesized from hydroxycinammates derivatives and salicylic acid. These materials which were capable of releasing molecules with biological potential upon hydrolysis, are also described in this work. The results indicate that hydrophobic interactions between PVP and the synthesized polyanhydrides could be responsible for the hydrogel formation and blend miscibility as well. PVP/Polyanhydride physical hydrogels were obtained from cast films. Micro- and nanofibers were also obtained by electrospinning. Thus, the present work contributes with the development of the new generation of smart dressings for wound and burn healing.

Lors de leur utilisation à l’échelle industrielle, les membranes polymères de filtration sont régulièrement soumises à des sollicitations chimiques lors des étapes de nettoyage et de désinfection. Bien que ces opérations restent inévitables pour restaurer les performances des membranes et prévenir la prolifération des micro-organismes, il s’avère néanmoins qu’elles conduisent à un vieillissement prématuré des membranes en conduisant à l’altération de leurs performances de filtration. L’objectif de cette thèse était d’étudier l’impact de l’hypochlorite de sodium, agent de nettoyage et de désinfection largement utilisé en industrie, sur les membranes en polyéthersulfone (PES) / polyvinylpyrrolidone (PVP). Des mesures électrocinétiques ont mis en évidence la dégradation du PES bien qu’il soit considéré comme un polymère très résistant chimiquement. Cette dégradation se produit par deux mécanismes distincts en fonction du pH de la solution d’hypochlorite de sodium : (i) la coupure de chaines du PES, principalement sous l’action de l’espèce HClO et (ii) l’hydroxylation du cycle aromatique du PES par les radicaux °OH formés au sein de la solution d’hypochlorite de sodium. La dégradation de la PVP par ouverture du cycle et son départ partiel de la membrane ont également été confirmés. Les expériences menées conjointement sur des membranes en PES pur et en PES/PVP avec différentes concentrations de PVP ont montré que la dégradation du PES par coupure de chaines se produit indépendamment de la concentration de la PVP dans la membrane. Par contre, la présence de la PVP favorise le mécanisme d’hydroxylation des cycles aromatiques du PES. Par ailleurs, le mécanisme de coupure de chaines du PES se révèle être le principal responsable de la détérioration des performances de filtration des membranes. Dans les conditions de vieillissement appliquées dans cette étude, ni l’hydroxylation du PES ni la dégradation de la PVP ne semblent jouer un rôle important dans la dégradation des propriétés de rétention des membranes. Enfin, la structure des membranes est fortement altérée sous l’action de l’hypochlorite de sodium, les modifications structurales étant plus importantes pour les membranes contenant de la PVP. / During industrial operations, filtration polymer membranes are regularly chemically-stressed during cleaning and disinfection steps. Although these latter are still unavoidable to restore the membrane performance and to prevent the proliferation of microorganisms, they lead, however, to membrane premature ageing, which impairs the membrane separation properties. The aim of this thesis was to investigate the impact of sodium hypochlorite, a widely used cleaning and disinfection agent, on polyethersulfone (PES) / polyvinylpyrrolidone (PVP) membranes. Electrokinetic measurements highlighted the degradation of PES, although the chemical resistance of this latter is well-acknowledged. The degradation of PES occurred through two distinct mechanisms depending on the pH of the sodium hypochlorite solution: (i) the PES-chain scission, which was found to result mainly from the HClO species, and (ii) the hydroxylation of the PES aromatic rings by the °OH free radicals that are formed in the sodium hypochlorite solution. Moreover, the degradation of PVP by a ring opening mechanism and its partial release from the membrane were confirmed. Experiments carried out with pure PES membranes as well as with PES / PVP membranes with different PVP contents showed that the PES-chain scission mechanism occurred whatever the PVP concentration. On the other hand, the presence of PVP was found to promote the hydroxylation of the PES aromatic rings. Furthermore, the PES-chain scission mechanism appeared to play the major role in the worsening of the membrane filtration performance. Under the ageing conditions of this study it seems that neither the PES hydroxylation nor the PVP degradation play a significant role in the worsening of the membrane rejection properties. Finally, the membrane structure was found to be substantially altered by the action of sodium hypochlorite, especially for membranes containing PVP.

The main focus of this project was to prepare transparent and conductive electrodes (TCEs). TCEs were made out of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and polyvinylpyrrolidone (PVP). Based on the theoretical aspect, MWCNTs has emerged as a promising nanofiller in the polymer matrix due to its high electrical conductivity. As a nanofiller, MWCNTs were used with a small ratio of rGO with PVP as a polymer matrix in this project to prepare TCEs having low sheet resistance with high transparency. An appropriate amount of PVP has been shown to be a good combination with MWCNTs and rGO in the solvent to keep MWCNTs dispersed for a long time. Carboxyl group (-COOH) functionalized MWCNTs (FMWCNTs) was produced in a controlled oxidative procedure due to enabling good dispersion of FMWCNTs in water and ethanol solvents. In contrast, water dispersible rGO was chemically prepared by using GO and sodium borohydride where GO was produced from graphite by using improved Hummer's method. Drop casting and spray coating methods were applied to fabricate TCEswhere only water was used as the solvent for drop casted TCEs and a mixing ratio of water and ethanol was 70:30 as solvent for spray coated TCEs. It was also determined in this project that the spray coating method was more suitable for preparing TCEs rather than thedrop casting method due to easy fabrication, large area coating possibility, and the smoothness of the coated film surface. The sheet resistance was obtained as 5026 Ω/ ⃣  where the transparency was 65% in the case of the drop casted electrode for the ratio of rGO:FMWCNTs:PVP was 1.2:60:1 with 0.02 mg FMWCNTs. In the case of spray coated electrode at the same ratio of rGO:FMWCNTs:PVP, the sheet resistance was measured as 5961 Ω/ ⃣  where the transparency was 73%. But in the case of 60:1 mass ratio of FMWCNTs:PVP with 0.02 mg FMWCNTs, the sheet resistance was 7729 Ω/ ⃣  and transparency was 77% for spray coated electrode. So, it is clear that the sheet resistance was improved by adding a small mass ratio of rGO with FMWCNTs:PVP.

L'exploitation de gisements pétroliers off shore doit souvent faire face à des problèmes de colmatage de conduites, notamment dus à la cristallisation d'hydrates de gaz. Actuellement, les opérateurs ont recours à des additifs antigels, dont l'efficacité est limitée par des conditions d'exploitation et des normes anti-pollution de plus en plus sévères. Aussi les recherches s'orientent-elles vers une nouvelle classe d'inhibiteurs dits à faible dose. Afin de comprendre l'influence de tels additifs, nous avons réalisé un réacteur haute pression muni d'un dispositif d'injection de liquide et d'un capteur turbidimétrique <i>in situ</i>. L'accès à la granulométrie de la suspension aux premiers stades de la cristallisation et à la consommation de gaz permet de caractériser la cinétique de formation de l'hydrate de méthane. Nous avons développé un protocole opératoire original qui autorise une maîtrise accrue de la germination des cristaux, grâce à un ensemencement initial de la solution. Le temps de latence devient alors un paramètre représentatif de l'efficacité des inhibiteurs. Nous avons alors évalué l'influence des conditions de pression et d'agitation sur l'évolution de la population de cristaux en l'absence d'additif. Puis nous avons déterminé l'effet inhibiteur d'un additif cinétique modèle, la polyvinylpyrrolidone (PVP). Mis en solution avant la cristallisation, il allonge la période de latence, diminue la vitesse de consommation du gaz et ralentit la création de nouvelles particules durant plusieurs heures. Par contre, lorsque ce polymère est injecté dans le milieu en cours de formation, il n'affecte plus la cinétique de la réaction. Nous donnons enfin les bases d'un modèle relevant des processus élémentaires de cristallisation : germination, croissance et agglomération des particules. Confrontée aux données expérimentales, une étude paramétrique nous a permis d'émettre des hypothèses quant à l'effet des inhibiteurs cinétiques sur la formation des hydrates de gaz.

N-vinyl-2-pyrrolidone, NVP, was polymerized by &amp / #56256 / &amp / #56394 / -radiation in the presence of atmospheric oxygen and under vacuum at different periods. Polymerization also conducted by using chemical initiator, &amp / #56256 / &amp / #56466 / -Azoisobutyronitrile, AIBN, in bulk at different temperatures and times. The activation energy for polymerization was found from Arrhenius plot as 31,8 kJ/mol. By using the Fox-Flory equation T&amp / #56256 / &amp / #56394 / and k values calculated for each polymerization methods. The polymer obtained was white gel type. The different types of polymer obtained were investigated by FT-IR, 1H-NMR and 13C-NMR, DSC, TGA and viscosity measurement methods. According to the FT-IR and NMR results, the polymerizations proceeded via vinyl group. As expected, solution viscosity measurements and DSC results showed that the glass transition temperature of polymer increases with increasing molecular weight.

More attention has been paid to find new type renewable energy sources because of increasing concern about the environmental problems arising from the combustion of fossil fuels as energy sources. The development of new storage materials will facilitate the use of hydrogen as a major energy carrier. Several possibilities exist for &lsquo / &lsquo / solid-state&rsquo / &rsquo / storage: the hydrogen can be trapped in metal organic frameworks, carbon nanotubes and certain alloys / or one can use materials in which hydrogen is already present in the composition (e.g., chemical hydrides). The latter option seems to be the most promising since it permits a higher mass ratio of hydrogen. Recently, ammonia-borane complex (NH3BH3, AB) has been considered as solid hydrogen storage material since it possess one of the highest hydrogen contents (19.6 wt. %) and high stability under the moderate conditions. Hydrolysis and methanolysis are the two reactions liberating hydrogen from AB. However, a catalyst is needed for hydrogen generation from methanolysis of AB. In this context, we aim to develop PVP-stabilized palladium(0) and ruthenium(0) nanoclusters as catalyst for the methanolysis of AB. The PVP-stabilized palladium(0) and ruthenium(0) nanoclusters were prepared from the in-situ reduction of palladium(II) acetylacetonate and ruthenium(III) chloride respectively in the methanolysis of AB. The prepared palladium(0) nanoclusters were isolated as solid materials by removing the volatile in vacuum and characterized by using TEM, SAED, XPS, FT-IR, XRD and UV-visible electronic absorption spectroscopy techniques while and ruthenium(0) nanoclusters were characterized by TEM, XPS, XRD, FT-IR and UV-visible electronic absorption spectroscopy techniques. The kinetics of methanolysis of AB catalyzed by palladium(0) and ruthenium(0) nanoclusters were studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of the catalytic methanolysis reaction obtained from the evaluation of kinetic data.