Dispersões coloidais estão presentes em muitas aplicações industriais e biológicas, tais como indústria de alimentos, cosméticos, produtos farmacêuticos e nanoestruturas. Devido a efeitos entrópicos, macromoléculas, quando imersas em uma solução de partículas pequenas, tendem a se aglomerar. Para evitar este fenômeno, cargas são adicionadas à superfície do colóide. Conseqüentemente, para manter o sistema neutro, a solução contém uma série de pequenos contraíons que neutralizam a carga do colóide. A inclusão de cargas pode evitar a aglomeração dos colóides, mas incorpora ao problema uma série de novos efeitos de natureza eletrostática. Todos estes efeitos, bem como o comportamento termodinâmico do sistema, no entanto, podem ser compreendidos analisando-se a distribuição de contraíons ao redor do colóide. Uma teoria muito simples que fornece esta distribuição de contraíons é a teoria de Poisson Boltzmann, na qual os contraíons são partículas pontuais e as interações eletrostáticas entre os íons são obtidas via potencial médio criado por todos os íons sobre um determinado contraíon, desconsiderando, desta forma, as correlações. Nesta tese respondemos à pergunta: quando correlações eletrostáticas e de tamanho são relevantes? Propusemos que correlações eletrostáticas são relevantes quando as interações eletrostáticas entre íos superam os efeitos entrópicos, ou seja, quando o parâmetro de plasma está acima de um certo limiar, G2d > 2. Sugerimos, também, que o tamanho dos íons torna-se relevante quando a fração de volume dos contraíons na superfície do colóide está acima de um limiar, ou seja, fs > 0,2. As duas propostas são testadas comparando-se os resultados obtidos via teoria de Poisson Boltzmann com os resultados provenientes de simulações. Em seguida, empregamos a teoria de Debye-Hückel Buraco Cavidade para incorporar correlações eletrostáticas. Comparamos os resultados obtidos via esta teoria com os resultados de simulações. Mostramos que a incorporação dos efeitos de correlações eletrostáticas resultam em um maior número de contraíos próximos à superfície do macroíon do que o observado via teoria de Poisson Boltzmann. Depois, introduzimos duas teorias de funcionais de densidade ponderada que incluem efeitos de correlações de tamanho: funcional de densidade ponderada com um peso baseado na teoria Debye-Hückel Buraco Cavidade e uma funcional de densidade ponderada com um peso constante. Comparamos os resultados obtidos através destas duas teorias com simulações, e observamos que a segunda teoria apresenta uma melhor concordância com as simulações. De maneira geral, as correlações de tamanho deixam os íons mais afastados do colóide do que o predito via teoria de Poisson Boltzmann. Finalmente, propusemos uma combinação da teoria Debye-Hückel-Buraco-Cavidade e funcional de densidade ponderada com um peso constante para tratar de problemas onde tanto correlações eletrostáticas como de tamanho se façam presentes. Observamos que para G2d < 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria de Poisson Boltzmann; para G2d > 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria Debye-Hückel-Buraco-Cavidade, pois somente correlações eletrostáticas são relevantes; para G2d < 2 e fs > 0,2 a teoria mista oferece o mesmo resultado que a teoria funcional de densidade ponderada com um peso constante; para G2d ≈ 2 e fs ≈ 0,2 ocorre uma compensação entre efeitos e a teoria mista fornece o mesmo resultado que a teoria de Poisson Boltzmann. Para G2d > 2 and fs > 0,2 efeitos de tamanho dominam e a teoria mista oferece os mesmos resultados que a teoria da funcional de densidade ponderada com umpeso constante. / Colloidal dispersions are present in many industrial and biological applications going from food, cosmetics, pharmaceutical and nanostructures. Due to entropic effects the large macromolecules in a solvent made of small particles, agglomerate. In order to avoid this effect, charged groups are added to the colloidal surface. Consequently in order to keep the charge neutrality the solution is full of counterions. The addition of charges might stop agglomeration but adds a number of new phenomena that are deeply related to the distribution of the counterions around the macroion. One simple theory that describes this distribution is the Poisson Boltzmann approach in which the counterions are assumed to be point ions and where the electrostatic interactions between the counterions are taken into account as the average field on a singel ions, ignoring correlations. In this thesis we address the question; when does electrostatic correlations and the size of the counterions are relevant? We propose that electrostatic correlations are relevant when the electrostatic interactions between the ions are bigger than the entropic effects. This assumption can be expressed by the plasma parameter being above a certain threshold, G2d > 2. We also propose that the size of the counterions become relevant when the volume fraction of ions at the surface of the colloid is above a certain threshold fs > 0.2. This two propositions are tested comparing results obtained with the PB theory with simulations. We then propose a theory to take into account the electrostatic correlations, the Debye-Hückel-Hole-Cavity and test this approach with simulations. The electrostatic correlation leads to more ions close to the colloid than the Poisson Boltzmann predicts. Next, we present two different approaches to account for size effects, the Weight Density Approximation based in the Debye-Hückel-Hole-Cavity theory and the Weight Density Approximation based in a constant weight. Comparison with simulations show that the second approach gives a better agreement. The size correlations leads to less ions close to the colloid than the Poisson Boltzmann approach predicts. Finally we propose a combination of the Debye-Hückel-Hole-Cavity and the Weight Density Approximation based in a constant weight to be the theory able to take into account both electrostatic and size correlations. Our result shows that for G2d <2 and fs <0.2 electrostatic and size correlations are irrelevant so Poisson Boltzmann is a good approach; for G2d > 2 and fs < 0.2 electrostatic correlations dominates and Debye-Hückel-Hole-Cavity gives a good approach; G2d < 2 and fs > 0.2 the Weight Density Approximation based in a constant weight gives the correct behavior; for G2d ≈ 2 and fs ≈ 0.2 the electrostatic correlation effects cancel the size effects and Poisson Boltzmann gives a good approximation. For G2d > 2 and fs > 0.2 size effects dominate.

Made available in DSpace on 2014-06-11T19:25:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-08-22Bitstream added on 2014-06-13T19:11:58Z : No. of bitstreams: 1 franca_dcc_me_araca.pdf: 2609587 bytes, checksum: 8a7904cdb64c406b06f726af6ac60fbc (MD5) / Universidade Estadual Paulista (UNESP) / No presente estudo foram utilizados 60 ratos submetidos a implantes subcutâneos de quatro elastômeros de silicone, sendo três usados em prótese bucomaxilofacial, LIM 6050, MDX 4-4210 e Silastic 732 RTV industrial e um indicado para cirurgia plástica, o Silimed. O objetivo do estudo foi avaliar os materiais em relação à compatibilidade biológica tecidual, nos tempos pós-operatórios de sete, quinze e trinta dias, quando os animais foram sacrificados e as peças processadas e coradas pela hematoxilina e eosina para análise qualitativa e quantitativa dos espécimes. Pelo estudo histomorfométrico, oito áreas de 60,11 mm2 foram analisadas, contando-se as células mesenquimais, inflamatórias mononucleares, eosinófilos e as células gigantes do tipo corpo estranho. O experimento foi desenvolvido em dois capítulos, estudando-se separadamente os silicones de uso em prótese e o Silimed. No primeiro capítulo, a análise da biocompatibilidade dos implantes subcutâneos dos elastômeros de silicone LIM 6050, MDX 4-4210 e Silastic 732 RTV industrial, observou-se biocompatibilidade aceitável em todos eles, considerando-se o fato de que sua indicação protética dependeria em especial das características físicas próprias de cada material, pela mínima reação tecidual observada, além de que em sua forma sólida é fácil a adaptação aos tecidos. No segundo capítulo, o estudo se baseou na análise das reações referentes ao implante de silicone utilizado em cirurgia plástica (Silimed), constatando-se a presença de processo inflamatório ligeiramente maior no silicone gel em relação aos outros grupos, porém com níveis aceitáveis de biocompatibilidade, confirmada pela rara presença de células gigantes do tipo corpo estranho. Todos os dados foram submetidos à análise de variância e teste de Tukey, demonstrando que todos os materiais implantados iniciaram uma resposta... / In the present study 60 rats were submitted to subcutaneous implant of four elastomers of silicon, being three of use in bucomaxillofacial prosthesis, LIM 6050, MDX 4-4210 and Silastic 732 RTV industrial and a suitable one for plastic surgery, Silimed. The objective of the study was to evaluate the materials in relation to the tissue biological compatibility, in the postoperative times of seven, fifteen and thirty days, when the animals were sacrificed and the processed pieces and stained for the hematoxilin and eosin for qualitative and quantitative analysis of the specimens. For the histomorphometric study, eight areas of 60,11 mm2 were analyzed, being counted the mesenchimal cells, inflammatory cells, eosinophile and giant cells. The experiment was developed in two chapters, being studied the use silicons separately in prosthesis and Silimed. In the first chapter, the analysis of the biocompatibility of the subcutaneous implant of the elastomers of silicon LIM 6050, MDX 4-4210 and Silastic 732 RTV industrial, acceptable biocompatibility was observed in all of them, being considered the fact that your prosthetic indication would especially depend on the own physical characteristics of each material, for the low tissue reaction observed, in addition in your solid form it is easy the adaptation to the tissues. In the second chapter, the study based on the analysis of the referring reactions to the it implants of silicon used in plastic surgery (silimed), being verified the presence of inflammatory process lightly larger in relation to the other groups, however with acceptable levels of biocompatibility confirmed by the rare presence of giant cells of the type strange body. All the data were submitted to the variance analysis and test of Tukey, demonstrating that all the implanted materials began an acceptable tissue inflammatory reaction, with tissue reactions of light intensity the moderate... (Complete abstract, click electronic address below)

Dispersões coloidais estão presentes em muitas aplicações industriais e biológicas, tais como indústria de alimentos, cosméticos, produtos farmacêuticos e nanoestruturas. Devido a efeitos entrópicos, macromoléculas, quando imersas em uma solução de partículas pequenas, tendem a se aglomerar. Para evitar este fenômeno, cargas são adicionadas à superfície do colóide. Conseqüentemente, para manter o sistema neutro, a solução contém uma série de pequenos contraíons que neutralizam a carga do colóide. A inclusão de cargas pode evitar a aglomeração dos colóides, mas incorpora ao problema uma série de novos efeitos de natureza eletrostática. Todos estes efeitos, bem como o comportamento termodinâmico do sistema, no entanto, podem ser compreendidos analisando-se a distribuição de contraíons ao redor do colóide. Uma teoria muito simples que fornece esta distribuição de contraíons é a teoria de Poisson Boltzmann, na qual os contraíons são partículas pontuais e as interações eletrostáticas entre os íons são obtidas via potencial médio criado por todos os íons sobre um determinado contraíon, desconsiderando, desta forma, as correlações. Nesta tese respondemos à pergunta: quando correlações eletrostáticas e de tamanho são relevantes? Propusemos que correlações eletrostáticas são relevantes quando as interações eletrostáticas entre íos superam os efeitos entrópicos, ou seja, quando o parâmetro de plasma está acima de um certo limiar, G2d > 2. Sugerimos, também, que o tamanho dos íons torna-se relevante quando a fração de volume dos contraíons na superfície do colóide está acima de um limiar, ou seja, fs > 0,2. As duas propostas são testadas comparando-se os resultados obtidos via teoria de Poisson Boltzmann com os resultados provenientes de simulações. Em seguida, empregamos a teoria de Debye-Hückel Buraco Cavidade para incorporar correlações eletrostáticas. Comparamos os resultados obtidos via esta teoria com os resultados de simulações. Mostramos que a incorporação dos efeitos de correlações eletrostáticas resultam em um maior número de contraíos próximos à superfície do macroíon do que o observado via teoria de Poisson Boltzmann. Depois, introduzimos duas teorias de funcionais de densidade ponderada que incluem efeitos de correlações de tamanho: funcional de densidade ponderada com um peso baseado na teoria Debye-Hückel Buraco Cavidade e uma funcional de densidade ponderada com um peso constante. Comparamos os resultados obtidos através destas duas teorias com simulações, e observamos que a segunda teoria apresenta uma melhor concordância com as simulações. De maneira geral, as correlações de tamanho deixam os íons mais afastados do colóide do que o predito via teoria de Poisson Boltzmann. Finalmente, propusemos uma combinação da teoria Debye-Hückel-Buraco-Cavidade e funcional de densidade ponderada com um peso constante para tratar de problemas onde tanto correlações eletrostáticas como de tamanho se façam presentes. Observamos que para G2d < 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria de Poisson Boltzmann; para G2d > 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria Debye-Hückel-Buraco-Cavidade, pois somente correlações eletrostáticas são relevantes; para G2d < 2 e fs > 0,2 a teoria mista oferece o mesmo resultado que a teoria funcional de densidade ponderada com um peso constante; para G2d ≈ 2 e fs ≈ 0,2 ocorre uma compensação entre efeitos e a teoria mista fornece o mesmo resultado que a teoria de Poisson Boltzmann. Para G2d > 2 and fs > 0,2 efeitos de tamanho dominam e a teoria mista oferece os mesmos resultados que a teoria da funcional de densidade ponderada com umpeso constante. / Colloidal dispersions are present in many industrial and biological applications going from food, cosmetics, pharmaceutical and nanostructures. Due to entropic effects the large macromolecules in a solvent made of small particles, agglomerate. In order to avoid this effect, charged groups are added to the colloidal surface. Consequently in order to keep the charge neutrality the solution is full of counterions. The addition of charges might stop agglomeration but adds a number of new phenomena that are deeply related to the distribution of the counterions around the macroion. One simple theory that describes this distribution is the Poisson Boltzmann approach in which the counterions are assumed to be point ions and where the electrostatic interactions between the counterions are taken into account as the average field on a singel ions, ignoring correlations. In this thesis we address the question; when does electrostatic correlations and the size of the counterions are relevant? We propose that electrostatic correlations are relevant when the electrostatic interactions between the ions are bigger than the entropic effects. This assumption can be expressed by the plasma parameter being above a certain threshold, G2d > 2. We also propose that the size of the counterions become relevant when the volume fraction of ions at the surface of the colloid is above a certain threshold fs > 0.2. This two propositions are tested comparing results obtained with the PB theory with simulations. We then propose a theory to take into account the electrostatic correlations, the Debye-Hückel-Hole-Cavity and test this approach with simulations. The electrostatic correlation leads to more ions close to the colloid than the Poisson Boltzmann predicts. Next, we present two different approaches to account for size effects, the Weight Density Approximation based in the Debye-Hückel-Hole-Cavity theory and the Weight Density Approximation based in a constant weight. Comparison with simulations show that the second approach gives a better agreement. The size correlations leads to less ions close to the colloid than the Poisson Boltzmann approach predicts. Finally we propose a combination of the Debye-Hückel-Hole-Cavity and the Weight Density Approximation based in a constant weight to be the theory able to take into account both electrostatic and size correlations. Our result shows that for G2d <2 and fs <0.2 electrostatic and size correlations are irrelevant so Poisson Boltzmann is a good approach; for G2d > 2 and fs < 0.2 electrostatic correlations dominates and Debye-Hückel-Hole-Cavity gives a good approach; G2d < 2 and fs > 0.2 the Weight Density Approximation based in a constant weight gives the correct behavior; for G2d ≈ 2 and fs ≈ 0.2 the electrostatic correlation effects cancel the size effects and Poisson Boltzmann gives a good approximation. For G2d > 2 and fs > 0.2 size effects dominate.

Dispersões coloidais estão presentes em muitas aplicações industriais e biológicas, tais como indústria de alimentos, cosméticos, produtos farmacêuticos e nanoestruturas. Devido a efeitos entrópicos, macromoléculas, quando imersas em uma solução de partículas pequenas, tendem a se aglomerar. Para evitar este fenômeno, cargas são adicionadas à superfície do colóide. Conseqüentemente, para manter o sistema neutro, a solução contém uma série de pequenos contraíons que neutralizam a carga do colóide. A inclusão de cargas pode evitar a aglomeração dos colóides, mas incorpora ao problema uma série de novos efeitos de natureza eletrostática. Todos estes efeitos, bem como o comportamento termodinâmico do sistema, no entanto, podem ser compreendidos analisando-se a distribuição de contraíons ao redor do colóide. Uma teoria muito simples que fornece esta distribuição de contraíons é a teoria de Poisson Boltzmann, na qual os contraíons são partículas pontuais e as interações eletrostáticas entre os íons são obtidas via potencial médio criado por todos os íons sobre um determinado contraíon, desconsiderando, desta forma, as correlações. Nesta tese respondemos à pergunta: quando correlações eletrostáticas e de tamanho são relevantes? Propusemos que correlações eletrostáticas são relevantes quando as interações eletrostáticas entre íos superam os efeitos entrópicos, ou seja, quando o parâmetro de plasma está acima de um certo limiar, G2d > 2. Sugerimos, também, que o tamanho dos íons torna-se relevante quando a fração de volume dos contraíons na superfície do colóide está acima de um limiar, ou seja, fs > 0,2. As duas propostas são testadas comparando-se os resultados obtidos via teoria de Poisson Boltzmann com os resultados provenientes de simulações. Em seguida, empregamos a teoria de Debye-Hückel Buraco Cavidade para incorporar correlações eletrostáticas. Comparamos os resultados obtidos via esta teoria com os resultados de simulações. Mostramos que a incorporação dos efeitos de correlações eletrostáticas resultam em um maior número de contraíos próximos à superfície do macroíon do que o observado via teoria de Poisson Boltzmann. Depois, introduzimos duas teorias de funcionais de densidade ponderada que incluem efeitos de correlações de tamanho: funcional de densidade ponderada com um peso baseado na teoria Debye-Hückel Buraco Cavidade e uma funcional de densidade ponderada com um peso constante. Comparamos os resultados obtidos através destas duas teorias com simulações, e observamos que a segunda teoria apresenta uma melhor concordância com as simulações. De maneira geral, as correlações de tamanho deixam os íons mais afastados do colóide do que o predito via teoria de Poisson Boltzmann. Finalmente, propusemos uma combinação da teoria Debye-Hückel-Buraco-Cavidade e funcional de densidade ponderada com um peso constante para tratar de problemas onde tanto correlações eletrostáticas como de tamanho se façam presentes. Observamos que para G2d < 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria de Poisson Boltzmann; para G2d > 2 e fs < 0,2 a teoria mista fornece os mesmos resultados que a teoria Debye-Hückel-Buraco-Cavidade, pois somente correlações eletrostáticas são relevantes; para G2d < 2 e fs > 0,2 a teoria mista oferece o mesmo resultado que a teoria funcional de densidade ponderada com um peso constante; para G2d ≈ 2 e fs ≈ 0,2 ocorre uma compensação entre efeitos e a teoria mista fornece o mesmo resultado que a teoria de Poisson Boltzmann. Para G2d > 2 and fs > 0,2 efeitos de tamanho dominam e a teoria mista oferece os mesmos resultados que a teoria da funcional de densidade ponderada com umpeso constante. / Colloidal dispersions are present in many industrial and biological applications going from food, cosmetics, pharmaceutical and nanostructures. Due to entropic effects the large macromolecules in a solvent made of small particles, agglomerate. In order to avoid this effect, charged groups are added to the colloidal surface. Consequently in order to keep the charge neutrality the solution is full of counterions. The addition of charges might stop agglomeration but adds a number of new phenomena that are deeply related to the distribution of the counterions around the macroion. One simple theory that describes this distribution is the Poisson Boltzmann approach in which the counterions are assumed to be point ions and where the electrostatic interactions between the counterions are taken into account as the average field on a singel ions, ignoring correlations. In this thesis we address the question; when does electrostatic correlations and the size of the counterions are relevant? We propose that electrostatic correlations are relevant when the electrostatic interactions between the ions are bigger than the entropic effects. This assumption can be expressed by the plasma parameter being above a certain threshold, G2d > 2. We also propose that the size of the counterions become relevant when the volume fraction of ions at the surface of the colloid is above a certain threshold fs > 0.2. This two propositions are tested comparing results obtained with the PB theory with simulations. We then propose a theory to take into account the electrostatic correlations, the Debye-Hückel-Hole-Cavity and test this approach with simulations. The electrostatic correlation leads to more ions close to the colloid than the Poisson Boltzmann predicts. Next, we present two different approaches to account for size effects, the Weight Density Approximation based in the Debye-Hückel-Hole-Cavity theory and the Weight Density Approximation based in a constant weight. Comparison with simulations show that the second approach gives a better agreement. The size correlations leads to less ions close to the colloid than the Poisson Boltzmann approach predicts. Finally we propose a combination of the Debye-Hückel-Hole-Cavity and the Weight Density Approximation based in a constant weight to be the theory able to take into account both electrostatic and size correlations. Our result shows that for G2d <2 and fs <0.2 electrostatic and size correlations are irrelevant so Poisson Boltzmann is a good approach; for G2d > 2 and fs < 0.2 electrostatic correlations dominates and Debye-Hückel-Hole-Cavity gives a good approach; G2d < 2 and fs > 0.2 the Weight Density Approximation based in a constant weight gives the correct behavior; for G2d ≈ 2 and fs ≈ 0.2 the electrostatic correlation effects cancel the size effects and Poisson Boltzmann gives a good approximation. For G2d > 2 and fs > 0.2 size effects dominate.

Dans un contexte de diversification des sources protéiques alimentaires, les protéines de pois représentent un ingrédient de choix et pourraient être associées à des protéines laitières comme celles du lactosérum dans la fabrication de nouveaux aliments. Dans ce travail, le comportement d’agrégation thermique (1h à 85°C), préalable à une gélification acide, des globulines de pois (Glob) seules et en mélange avec la β-lactoglobuline (βlg), a été étudié en fonction de la concentration totale en protéine, du ratio massique βlg/Glob et de la force ionique. La caractérisation des agrégats solubles a été réalisée par une combinaison de techniques analytiques telles que la détermination de l’hydrophobicité de surface, la quantification des ponts disulfures, la diffusion dynamique de la lumière (DLS), la chromatographie d’exclusion de taille (SEC-HPLC) et l’électrophorèse SDS-PAGE. La formation d’agrégats mixtes semble être gouvernée par des interactions intermoléculaires non covalentes, mais aussi des liaisons covalentes entre la βlg et les sous-unités de légumine notamment à faible force ionique (5 mM NaCl). Ces dernières semblent contrôler les caractéristiques méso-structurales des agrégats mixtes formés (haut poids moléculaire et diamètre réduit < 110 nm) comparativement aux agrégats formés de globulines seules (diamètre > 150 nm). Le deuxième volet de l’étude concernait la formation de gels acides obtenus par acidification au glucono-δ-lactone, soit à partir des agrégats mixtes solubles caractérisés précédemment, soit à partir de mélanges d’agrégats thermiques de chaque protéine obtenus séparément. Les différents paramètres liés à la cinétique d’acidification et à la gélification (temps et pH de transition sol/gel, propriétés mécaniques par rhéologie dynamique et analyse de la microstructure par Microscopie Confocale à Balayage Laser, capacité de rétention d’eau) ont été évalués. Les résultats démontrent que les agrégats mixtes issus des mélanges thermisés des deux protéines permettent d’obtenir des gels plus élastiques avec une structure fibrillaire plus ordonnée et moins poreuse, avec des caractéristiques proches de celles des gels formés d’agrégats purs de Blg. / In the context of protein source diversification, pea protein is a promising ingredient and may be associated with milk proteins such as whey proteins in the production of new food products. In the present work, the thermal aggregation (85°C - 1 h) of pea globulins (Glob) alone and in admixture with β-lactoglobulin (βlg), prior to acid gelation, was studied as a function of total protein concentration, βlg/Glob weight ratio and ionic strength. The characterization of soluble aggregates was carried out by combining different analytical methods such as surface hydrophobicity determination, disulfide bridge quantification, dynamic light scattering (DLS), size exclusion chromatography (SEC-HPLC) and SDS-PAGE electrophoresis. The formation of mixed aggregates seems to be governed by non-covalent intermolecular interactions, but also by covalent bonds between βlg and legumin subunits at low ionic strength (5 mM NaCl). The latter seem to control the structural features of mixed aggregates (high molecular weight and reduced diameter <100 nm) compared to pure globulin aggregates (diameter > 150 nm). The second part of this work investigated the formation of acid gels by glucono-δ-lactone, obtained either from soluble mixed aggregates such as characterized previously, either from mixtures of thermal aggregates of the two proteins prepared separately. The parameters associated to acidification kinetics and gelation (time and pH at sol/gel transition, mechanical properties by dynamic rheology and microstructure analysis by Confocal Scanning Laser Microscopy, water holding capacity) were evaluated. The results showed that mixed aggregates from heat-treated initial mixtures of the two proteins provides more elastic acid gels with a more regular and less porous fibrillar structure having close characteristics to those of pure βlg gels.

Erythromycin (ERY) is a macrolide antibiotic which is used in the treatment of acne vulgaris.Acne is a common skin condition that occurs when the sebaceous glands and hair shafts become infected by the bacteria Propionibacterium acnes. Acne is a chronic condition that may last for years and the severity of the effects of the disease on patients is often undermined especially in third world countries where more emphasis is placed on other more life-threatening diseases. It may cause considerable physical and emotional distress to sufferers along with the possibility of permanent scarring. Although use of topical ERY formulations is not the first line of treatment it has proven to be effective in treating inflammation of skin and skin structures cause by the responsible bacteria. To-date there are a variety of vehicles which are used in preparing topical ERY formulations namely ointment and gel bases, alcoholic solutions and pledgets. All the gel formulations on the market contain hydroxypropyl cellulose, alcohol and water along with the active ingredient(s). However, some gel formulations contain propylene glycol in addition to these excipients an example being Emgel®. Propylene glycol has been shown to affect the penetration of topically applied drugs through the skin suggesting that it would be highly likely that those formulations which contain propylene glycol may release more ERY into the skin following application. With this in mind, two ERY gel formulations were produced which contained different percentages of propylene glycol. According to the FDA guidelines, pharmacokinetic measurements in blood, plasma and/or urine of topical dermatological drug products are not feasible to document bioequivalence since the active ingredient(s) in topical formulations is/are not intended to be absorbed into the systemic circulation and in addition, concentrations in extracutaneous biological tissues would generally not be measurable. This limits determination of bioavailability and assessment of bioequivalence of such products to pharmacodynamic measurements, clinical trials and dermatopharmacokinetic (DPK) measurements such as tape stripping (TS) and microdialysis (MD).TS is a sampling technique which involves sequential removal of layers of the stratum corneum using strips of adhesive tape. This technique has found increasing use in DPK studies for investigation of drug kinetics in the skin following the application of a topical formulation. The technique has also been used as a diagnostic tool in assessing the quality of the stratum corneum in diseased skin. In the current research study, the tape stripping technique was used to investigate the pharmaceutical/biological availability of topical gel formulations containing ERY. MD is another DPK sampling technique which has been used to determine the amount of a topically applied drug that penetrates through the stratum corneum to reach deeper tissues of the skin. The in vivo sampling technique involves the insertion of microdialysis probes beneath the skin surface in the dermal tissue and allows for real-time sampling of the analyte at its target site. Recently in vitro MD has also been successfully used to assess the pharmaceutical availability of a topical corticosteroid, mometesone furoate, from topical formulations. Based on this work, microdialysis was used to determine the pharmaceutical availability of ERY from gel formulations which were developed for use in this research. The results of the pharmaceutical availability of ERY from in vivo tape stripping studies and the in vitro microdialysis studies were compared to establish correlation between the data. Pharmaceutical equivalence and bioequivalence data obtained from the respective studies on the gel formulations were investigated by statistical analysis of the data generated from both the in vitro and in vivo experiments. In summary the objectives of this research were: 1. To develop and validate a high performance liquid chromatography method suitable to analyse ERY concentrations obtained from in vitro microdialysis studies and in vivo tape stripping studies. 2. To prepare two different ERY gel formulations with different percentage content of propylene glycol. 3. To determine the pharmaceutical availability of ERY from two different gel formulations using in vitro microdialysis. 4. To develop and validate a tape stripping technique which could be used to determine percutaneous penetration and bioequivalence of the gel formulations. 5. To compare in vitro microdialysis and in vivo tape stripping data and attempt to establish a correlation between the two different approaches.

The development of bio-resorbable implant materials is rapidly going on. Sterilization of those materials is inevitable to assure the hygienic requirements for critical medical devices according to the medical device directive (MDD, 93/42/EG). Biopolymer-containing biomaterials are often highly sensitive towards classical sterilization procedures like steam, ethylene oxide treatment or gamma irradiation. Supercritical CO2 (scCO2) treatment is a promising strategy for the terminal sterilization of sensitive biomaterials at low temperature. In combination with low amounts of additives scCO2 treatment effectively inactivates microorganisms including bacterial spores. We established a scCO2 sterilization procedure under addition of 0.25% water, 0.15% hydrogen peroxide and 0.5% acetic anhydride. The procedure was successfully tested for the inactivation of a wide panel of microorganisms including endospores of different bacterial species, vegetative cells of gram positive and negative bacteria including mycobacteria, fungi including yeast, and bacteriophages. For robust testing of the sterilization effect with regard to later application of implant materials sterilization all microorganisms were embedded in alginate/agarose cylinders that were used as Process Challenge Devices (PCD). These PCD served as surrogate models for bioresorbable 3D scaffolds. Furthermore, the impact of scCO2 sterilization on mechanical properties of polysaccharide-based hydrogels and collagen-based scaffolds was analyzed. The procedure was shown to be less compromising on mechanical and rheological properties compared to established low-temperature sterilization methods like gamma irradiation and ethylene oxide exposure as well as conventional steam sterilization. Cytocompatibility of alginate gels and scaffolds from mineralized collagen was compared after sterilization with ethylene oxide, gamma irradiation, steam sterilization and scCO2 treatment. Human mesenchymal stem cell viability and proliferation were not compromised by scCO2 treatment of these materials and scaffolds. We conclude that scCO2 sterilization under addition of water, hydrogen peroxide and acetic anhydride is a very effective, gentle, non-cytotoxic and thus a promising alternative sterilization method especially for biomaterials.

We present an experimental study on the formation and dissociation characteristics of carbon dioxide (CO2) gas hydrates using Raman spectroscopy. The CO2 hydrates were formed from sodium chloride/water solutions with salinities of 0–10 wt %, which were pressurized with liquid CO2 in a stirred vessel at 6 MPa and a subcooling of 9.5 K. The formation of the CO2 hydrate resulted in a hydrate gel where the solid hydrate can be considered as the continuous phase that includes small amounts of a dispersed liquid water-rich phase that has not been converted to hydrate. During the hydrate formation process we quantified the fraction of solid hydrate, xH, and the fraction of the dispersed liquid water-rich phase, xL, from the signature of the hydroxyl (OH)-stretching vibration of the hydrate gel. We found that the fraction of hydrate xH contained in the hydrate gel linearly depends on the salinity of the initial liquid water-rich phase. In addition, the ratio of CO2 and water was analyzed in the liquid water-rich phase before hydrate formation, in the hydrate gel during growth and dissociation, and after its complete dissociation again in the liquid water-rich phase. We observed a supersaturation of CO2 in the water-rich phase after complete dissociation of the hydrate gel and were able to show that the excess CO2 exists as dispersed micro- or nanoscale liquid droplets in the liquid water-rich phase. These residual nano- and microdroplets could be a possible explanation for the so-called memory effect.

This diploma thesis deals with hyaluronan modified by palmitoyl and its gelation. Gels were created from palmitoyl hyaluronan with molecular weight 216 kDa and degree of substitution 11 % in concentrations 15 and 20 g dm-3 in water and concentrations 10, 15, 20 g dm-3 in NaCl and TSB. Also gel from palmitoyl hyaluronan with molecular weight 35 kDa and degree of substitution 10 % in concentrations 20, 30 g dm-3 in NaCl was created. Gels were investigated concerning medical applications. Gels were rigid and had very good properties, which was confirmed by rheology. The physical properties (pH, water content) of gels and stability were investigated. On the grounds of the MTT test, three methods of cell incorporation were suggested. Gels are nontoxic, biocompatible, and biodegradable with nontoxic degradation products and that is why they are excellent aspirants for use in biomedicine.

This thesis deals with bond strength of metal ions in humic gels. Several samples of humic acids were studied to consider influence of samples isolation process and their consequent characteristics on bond strength of metal ions in their complexes. Some functional groups was blocked by methylation at some samples. Amount of active functional groups in individual samples was determined by standard titration methods. Metal ions bound in humic complexes were divided into several fractions by extraction with different reagents (distilled water, 1M MgCl2, 1M HCl and 0,025M NH4EDTA). Two extraction methods were used: sequential and fractional. During the fractional extraction leaching of metal ions always proceeds in single agents from original komplex, whereas during the sequential extraction leaching proceeds gradually in all extraction agents in order according to rising afinity of agents, i.e. bond strength of metal ions in samples. Amount of metal ions in leaches after extractions was analysed by UV-VIS spektrometry.