La maladie d’Alzheimer (MA) est caractérisée par deux lésions neuropathologiques: les plaques séniles (composées essentiellement du peptide amyloïde Ab) et les dégénérescences neurofibrillaires (DNF, composées de formes hyperphosphorylées de protéines tau). Les mécanismes de formation des DNF sont encore mal compris et notre travail expérimental a eu pour objectifs d’étudier certaines hypothèses de formation des DNF.<p>1° Une hypothèse étiopathogénique de la MA est la “cascade amyloïde”, selon laquelle le peptide amyloïde Ab exercerait un effet toxique entraînant la phosphorylation de tau et la formation de DNF. Certaines formes familiales de MA sont dues à des mutations du gène du précurseur du peptide amyloïde (APP) ou des présénilines et nous avons voulu déterminer si la surexpression de ces protéines pouvait entraîner la formation de DNF. Nous avons d’abord étudié une lignée murine double transgénique surexprimant l’isoforme 0N3R de protéine tau humaine “sauvage” et une forme mutée de préseniline 1 (M146L). Nous y avons démontré une co-expression neuronale des deux protéines et une augmentation de la phosphorylation de tau mais nous n’y avons pas observé de formation de DNF, chez des animaux examinés jusqu’à 17 mois. Nous avons ensuite étudié une lignée murine triple transgénique surexprimant l’isoforme 0N3R de protéine tau “sauvage”, une forme mutée de préseniline 1 (M146L) et une forme mutée de l’APP 751 (mutations Swedish K670N, M671L et London V717I). Ces animaux ont développé précocement (2.5 mois) des dépôts extracellulaires de peptide Ab. Nous y avons observé une augmentation de la phosphorylation de tau dans les prolongements neuronaux en contact avec les dépôts amyloïdes et des anomalies de l’organisation du cytosquelette, mais pas de DNF, chez des animaux examinés jusqu’à 18 mois.<p>2° Certaines mutations du gène de tau sont responsables de formes familiales de démence frontotemporales dans lesquelles se développent des DNF. Ces mutations favoriseraient l’agrégation de tau où entraîneraient un déséquilibre de l’expression relative des isoformes de tau. Un tel déséquilibre pourrait également être induit dans les formes sporadiques de MA, en l’absence de mutations de tau. Afin d’investiguer cette hypothèse, nous avons étudié le profil d’expression des ARNm de tau et des isoformes de protéines tau dans plusieurs régions cérébrales de sujets contrôles ou atteints de MA. Un même profil d’expression a été observé dans les deux groupes. Une augmentation relative de l’expression de l’isoforme 0N3R de tau dans le cortex temporal pourrait être liée à la sensibilité de cette région au développement de DNF. Nous avons également étudié des lignées stables de cellules CHO exprimant des formes mutées (P301L, R406W) et non-mutées de protéines tau. Nous n’avons cependant pas observé d’augmentation de l’agrégation de tau dans les lignées exprimant les formes mutées de tau.<p>Nos résultats indiquent que la simple surexpression de formes mutées de l’APP et des présénilines, même en présence d’une protéine tau humaine, ne suffit pas à entraîner la formation de DNF. En outre, l’absence de différence dans le profil d’expression cérébrale des isoformes de tau entre sujets contrôles et atteints de MA suggère que les modifications post-traductionnelles de cette protéine jouent un rôle plus important dans la genèse des DNF.<p> / Doctorat en sciences biomédicales / info:eu-repo/semantics/nonPublished

L’analyse du mécanisme d’interaction de l’héparane sulfate protéoglycane (HSPG) avec lesprotéines amyloïdes et l’effet de paramètres physiologiques (pH,…) sur ce mécanisme nouspermettent une meilleure compréhension des mécanismes menant à l’amyloïdogenèse.La transthyrétine (TTR), molécule circulant à la fois dans le plasma et dans le liquidecéphalo-rachidien, est une des protéines impliquée dans les amyloses. Elle est responsable desamyloses à la TTR et elle joue un rôle dans la maladie d’Alzheimer en séquestrant la protéinebêta-amyloïde (Aβ). La biochromatographie est un outil très efficace pour analyser lemécanisme entre un ligand et son récepteur dans des conditions modulables et se rapprochantdes conditions biologiques. De plus, les nanotubes de carbones (NTCs) peuvent être utiliséspour détecter ou transporter des molécules qui se lient sur leur surface externe et peuventinteragir avec d’autres composés. Au cours de ce travail, un support particulaire a été utilisé où l’HSPG est immobilisé sur desparticules de silice pré-activées par des résidus amines. Ce support remplissant une colonnechromatographique a permis dans un premier temps d’étudier et de comparer les mécanismesd’association entre l’HSPG et une forme sauvage de la TTR et une forme sénile de la TTRextraite d’un patient décédé des suites d’une amylose sénile à la TTR. Cette étude a montréque pour la TTR sauvage, l’association avec l’HSPG est indépendante du pH et implique desinteractions faibles. Pour la TTR sénile, cette association est dépendante du pH. A pH<6,5, laprotonation d’un résidu histidine est observée. De plus, l’étude des paramètresthermodynamiques et de la compensation enthalpie/ entropie montrent un changement dans lemécanisme de fixation avec l’apparition d’interactions ioniques à pH<6,5. Un pH acide estnécessaire pour dissocier et dénaturer partiellement la TTR. L’affinité de la TTR avec l’HSPGdépend de la structure tétramérique quaternaire de la TTR qui présente alors des résiduscapables de créer des interactions. Dans un deuxième temps, cette colonne a permis d’évaluerl’effet de la TTR et du pH sur la liaison Aβ/HSPG. Comme précédemment, la protonationd’un résidu histidine présent sur la Aβ est observée à pH<6,5. Ce résultat confirme des étudesmenées auparavant sur le précurseur de la protéine Aβ. Les résultats thermodynamiques ontmis en évidence que l’affinité de Aβ avec l’HSPG diminuait avec la concentration croissanteen TTR et l’étude des chromatogrammes associés a montré que la TTR ne séquestrait passeulement Aβ mais la clivait en fragments plus courts qui diminuent son affinité avecl’HSPG. Dans la maladie d’Alzheimer, la TTR exerce une activité protéolytique vis-à-vis deAβ.2. Dans un troisième temps, l’effet de la fonctionnalisation de la TTR par des nanotubes decarbone sur la liaison TTR/HSPG a été étudié. Les résultats obtenus montrent que lesinteractions entre l’HSPG et la TTR-NTC sont de type van der Waals et hydrogène. Lesparamètres thermodynamiques des liaisons TTR/HSPG et TTR-NTC/HSPG sont similairespour des pH>6. A pH<6, il n’existe quasiment pas de différences entre les valeurs obtenues àpH >6 et celles obtenues à pH<6. Les NTCs empêcheraient la formation de liaisons ioniques / The analysis of the heparan sulfate proteoglycan (HSPG) association mechanism withamyloid proteins and the effect of physiological parameters (pH,…) on this mechanism allowa better understanding of the mechanisms leading to amyloidogenesis.Transthyretin (TTR), which circulates in both plasma and cerebrospinal fluid, is one of theproteins involved in amyloidosis. It leads to TTR amyloidosis and plays a role in Alzheimer’sdisease in sequestrating the beta-amyloid (Aβ) protein. Biochromatography is an effectivetool for the analysis of the mechanism involved between a ligand and its receptor inadjustable conditions which could be close to biological conditions. Moreover, carbonnanotubes can be used to detect or to carry molecules which bind on its external surface andcould interact with other molecules. In this work, a particulate support was used where the HSPG was immobilized on the silica particles preactivated by amine residues. This support filling a column was used to study andcompare association mechanisms between HSPG and a wild type TTR form and a senile formof the TTR which was was extracted from a patient who died of cardiac failure with a senilesystemic amyloid. This study showed that the association between wild type TTR and HSPGwas independent of the pH and involved weak interactions.For the senile TTR, this association was dependent on pH. At pH<6,5, a histidine residue wasprotonated. Moreover, the study of both thermodynamical parameters and enthalpy-entropycompensation showed a change in the association mechanism with involvement of more ionicinteractions at pH<6,5. An acidic pH was necessary to dissociate and partially denaturate theTTR. The affinity of the TTR with HSPG depends on the tetrameric quaternary structure ofthe TTR which presents some residues which are able to create interactions.In a second time, this column was used to evaluate the effect of both the TTR and the pH onAβ/HSPG binding. As previously, the protonation of a histidine residue present on Aβ wasobserved at pH<6,5. This result confirmed studies on the Aβ precursor. Thermodynamicalvalues highlighted that the affinity of Aβ for l’HSPG decreased with the increase of TTRconcentration, and the study of the chromatograms associated showed that TTR sequestratedAβ and cut Aβ in smaller fragments which decreased its affinity for HSPG. In Alzheimer’sdisease, TTR has a proteolytic activity on Aβ.In a third time, the effect of the carbon nanotubes (CNTs), immobilized on TTR, on theTTR/HSPG binding was studied. Results showed that interactions between TTR-NTC andHSPG are van der Waals and hydrogen. Thermodynamical data of TTR/HSPG et TTRNTC/HSPG bindings are similar at pH>6. At pH<6, no differences between values obtainedat all pH values for TTR-NTC. NTCs would avoid ionic interactions formations.

Textile UV-radiation sensors has lately been introduced to the field of smart textiles. Inkjet printing has been used as means of application due to the effective and resource efficient process. UV-LED radiation curing has been used in combination with inkjet printing in favour of low energy requirements, solvent free solution and reduced risk of clogging in the print heads. The problems arising when exposing photochromic prints to UV-radiations are that oxygen inhibition during the curing and photo-oxidation in the print reduces the prints ability to develop colour. It is the oxygen in the air in combination with UV-radiation that gives the photo-oxidating behavior. The aim of the study is to with the aid of physical protection reduce the effect of oxygen inhibition and photo-oxidation in the prints. Three types of physical treatments were used, wax coating, protein based impregnation and starch based impregnation. Treatments were applied before curing as well as after curing and the colour development after activation during 1 min of UV-radiation was measured with a spectrophotometer. Multiple activations were also tested to see how the treatments affected the fatigue behaviour of the prints over time. The aim was to have as high colour development as possible reflecting reduced oxygen inhibition and photo-oxidation. Results showed significantly higher colour development for samples treated with wax and whey powder before curing, but reduced colour development for amylose impregnation. Over time whey powder before curing showed highest colour development due to highest initial colour development. Lowest fatigue was seen for washed samples containing the chemical stabiliser HALS, showing an increased colour development. In reference to earlier studies the protective properties of wax and whey powder is due to their oxygen barrier properties protecting the print. The tested treatments have shown that it is possible to reduce the effect of photo-oxidation during curing leading to prints giving higher colour development. This gives a great stand point when improving existing and future application of photochromic prints on textiles.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Esta tese apresenta os estudos realizados quanto à síntese e caracterização de microgéis termo-responsivos de N-isopropilacrilamida (NIPAM) e macromoléculas de origem amilácea em sua composição, sistemas ainda pouco explorados na literatura. Inicialmente, nanopartículas de amido (SNP) foram preparadas por nanoprecipitação para incorporação nos microgéis de interesse, através da dissolução dos grânulos do amido em DMSO/H2O, aplicação de ultrassom e precipitação em não-solvente. As SNPs preparadas foram utilizadas como copolímero para formação de microgéis híbridos do tipo SNP-co-p(NIPAM) através de polimerização em emulsão na presença e na ausência de surfactante. A influência das SNPs nas propriedades dos microgéis foi estudada por MEV, DLS, PZ e SAXS, onde foram observadas mudanças no comportamento físico-químico e estrutura supramolecular dos microgéis. No geral, observaram-se deslocamentos da temperatura de transição de fase para valores maiores (até 35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro), aumento da estabilidade coloidal e organização dos polímeros presentes no microgel em uma arquitetura caroço-casca. As propriedades de inchamento dos microgéis também foram estudadas através da teoria de Flory-Rehner, onde a temperatura theta e o grau de polimerização entre dois pontos de reticulação foram determinados através do ajuste apropriado do parâmetro de interação (χ). Paralelamente, visando um sistema diferente do descrito acima, foi estudado um novo agente de reticulação baseado nos polímeros do amido, a amilose e a amilopectina. Para isso, os polímeros do amido que compõem as nanopartículas foram modificados para a utilização como agente de reticulação na síntese de microgéis de p(NIPAM). Nesta etapa, uma reação de substituição dos grupos hidroxila dos polímeros do amido foi realizada com o cloreto de acriloíla de forma a inserir insaturações na estrutura dos polímeros, para que estes fossem aplicados como reticulante. O sucesso da reação de modificação foi verificado através de RMN 1H e FTIR, no qual um maior grau de substituição foi obtido quando um tempo maior de reação foi empregado. Microgéis de p(NIPAM) foram então preparados através de polimerização em emulsão utilizando os reticulantes sintetizados. Observou-se a influência do grau de substituição e da concentração do reticulante nos microgéis, analisados por MEV, DLS e UV-Vis com controle de temperatura. As principais mudanças foram relativas à temperatura de transição de fase e tamanho dos microgéis. Utilizando o agente de reticulação com maior grau de substituição, foi possível deslocar a temperatura de transição de fase dos microgéis preparados para valores maiores (35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro). Observou-se também uma resposta mecânica da rede do microgel, que refletiu no tamanho das partículas, influenciada pela concentração dos agentes de reticulação e do grau de substituição. Quanto maior a concentração e o grau de substituição do agente de reticulação, maior a resistência ao intumescimento observado no microgel. / This thesis presents the studies regarding the synthesis and characterization of thermoresponsive microgels of N-isopropylacrylamide (NIPAM) and amylaceous-based macromolecules, which are systems still little explored in the literature. At first, starch nanoparticles (SNP) were prepared by nanoprecipitation, through dissolution of starch granules in DMSO/H2O, ultrasound application and non-solvent precipitation. SNPs were then used as copolymer in SNP-co-p(NIPAM) hybrid microgels synthesized by emulsion polymerization in the presence and absence of surfactant. The influence of SNPs in microgel properties were studied by SEM, DLS, ZP, and SAXS, where changes in the physicalchemical behavior and supramolecular structure were observed. Summing up, shifts in the phase transition temperature up to 35 °C, increased colloidal stability, and microgel polymers organization into a core-shell structure were observed. Microgels swelling behaviour were also studied by the Flory-Rehner theory, where the theta-temperature and the degree of polymerization between two crosslinker points were determined through interaction parameter (χ) fitting. In parallel, a new starch-based crosslinker was studied. For this purpose, starch polymers (amylose and amylopectin within the SNPs) were modified in order to use them as crosslinker in p(NIPAM) microgel synthesis. In this step, a substitution reaction in hydroxyl groups of SNP was carried out with acryloyl chloride, where double bonds were attached in polymers structure, making it suitable as a crosslinker. Reaction performances were evaluated through 1H NMR and FTIR. Then, p(NIPAM) microgels were prepared by emulsion polymerization using the crosslinker synthesized. The degree of substitution and the crosslinker concentration influence were verified and analyzed by SEM, DLS and UV-Vis with temperature control. The main observed changes were related to the phase transition temperature e microgels size. Using the crosslinker with higher substitution degree, it was possible the shift of the phase transition temperature to higher values (~35 °C). A mechanical response, observed trough microgels size, was found, driven by the crosslinker concentration and substitution degree. As higher the concentration and substitution degree of the crosslinker, higher was the swelling resistance observed in microgel structure.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Esta tese apresenta os estudos realizados quanto à síntese e caracterização de microgéis termo-responsivos de N-isopropilacrilamida (NIPAM) e macromoléculas de origem amilácea em sua composição, sistemas ainda pouco explorados na literatura. Inicialmente, nanopartículas de amido (SNP) foram preparadas por nanoprecipitação para incorporação nos microgéis de interesse, através da dissolução dos grânulos do amido em DMSO/H2O, aplicação de ultrassom e precipitação em não-solvente. As SNPs preparadas foram utilizadas como copolímero para formação de microgéis híbridos do tipo SNP-co-p(NIPAM) através de polimerização em emulsão na presença e na ausência de surfactante. A influência das SNPs nas propriedades dos microgéis foi estudada por MEV, DLS, PZ e SAXS, onde foram observadas mudanças no comportamento físico-químico e estrutura supramolecular dos microgéis. No geral, observaram-se deslocamentos da temperatura de transição de fase para valores maiores (até 35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro), aumento da estabilidade coloidal e organização dos polímeros presentes no microgel em uma arquitetura caroço-casca. As propriedades de inchamento dos microgéis também foram estudadas através da teoria de Flory-Rehner, onde a temperatura theta e o grau de polimerização entre dois pontos de reticulação foram determinados através do ajuste apropriado do parâmetro de interação (χ). Paralelamente, visando um sistema diferente do descrito acima, foi estudado um novo agente de reticulação baseado nos polímeros do amido, a amilose e a amilopectina. Para isso, os polímeros do amido que compõem as nanopartículas foram modificados para a utilização como agente de reticulação na síntese de microgéis de p(NIPAM). Nesta etapa, uma reação de substituição dos grupos hidroxila dos polímeros do amido foi realizada com o cloreto de acriloíla de forma a inserir insaturações na estrutura dos polímeros, para que estes fossem aplicados como reticulante. O sucesso da reação de modificação foi verificado através de RMN 1H e FTIR, no qual um maior grau de substituição foi obtido quando um tempo maior de reação foi empregado. Microgéis de p(NIPAM) foram então preparados através de polimerização em emulsão utilizando os reticulantes sintetizados. Observou-se a influência do grau de substituição e da concentração do reticulante nos microgéis, analisados por MEV, DLS e UV-Vis com controle de temperatura. As principais mudanças foram relativas à temperatura de transição de fase e tamanho dos microgéis. Utilizando o agente de reticulação com maior grau de substituição, foi possível deslocar a temperatura de transição de fase dos microgéis preparados para valores maiores (35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro). Observou-se também uma resposta mecânica da rede do microgel, que refletiu no tamanho das partículas, influenciada pela concentração dos agentes de reticulação e do grau de substituição. Quanto maior a concentração e o grau de substituição do agente de reticulação, maior a resistência ao intumescimento observado no microgel. / This thesis presents the studies regarding the synthesis and characterization of thermoresponsive microgels of N-isopropylacrylamide (NIPAM) and amylaceous-based macromolecules, which are systems still little explored in the literature. At first, starch nanoparticles (SNP) were prepared by nanoprecipitation, through dissolution of starch granules in DMSO/H2O, ultrasound application and non-solvent precipitation. SNPs were then used as copolymer in SNP-co-p(NIPAM) hybrid microgels synthesized by emulsion polymerization in the presence and absence of surfactant. The influence of SNPs in microgel properties were studied by SEM, DLS, ZP, and SAXS, where changes in the physicalchemical behavior and supramolecular structure were observed. Summing up, shifts in the phase transition temperature up to 35 °C, increased colloidal stability, and microgel polymers organization into a core-shell structure were observed. Microgels swelling behaviour were also studied by the Flory-Rehner theory, where the theta-temperature and the degree of polymerization between two crosslinker points were determined through interaction parameter (χ) fitting. In parallel, a new starch-based crosslinker was studied. For this purpose, starch polymers (amylose and amylopectin within the SNPs) were modified in order to use them as crosslinker in p(NIPAM) microgel synthesis. In this step, a substitution reaction in hydroxyl groups of SNP was carried out with acryloyl chloride, where double bonds were attached in polymers structure, making it suitable as a crosslinker. Reaction performances were evaluated through 1H NMR and FTIR. Then, p(NIPAM) microgels were prepared by emulsion polymerization using the crosslinker synthesized. The degree of substitution and the crosslinker concentration influence were verified and analyzed by SEM, DLS and UV-Vis with temperature control. The main observed changes were related to the phase transition temperature e microgels size. Using the crosslinker with higher substitution degree, it was possible the shift of the phase transition temperature to higher values (~35 °C). A mechanical response, observed trough microgels size, was found, driven by the crosslinker concentration and substitution degree. As higher the concentration and substitution degree of the crosslinker, higher was the swelling resistance observed in microgel structure.

Esta tese apresenta os estudos realizados quanto à síntese e caracterização de microgéis termo-responsivos de N-isopropilacrilamida (NIPAM) e macromoléculas de origem amilácea em sua composição, sistemas ainda pouco explorados na literatura. Inicialmente, nanopartículas de amido (SNP) foram preparadas por nanoprecipitação para incorporação nos microgéis de interesse, através da dissolução dos grânulos do amido em DMSO/H2O, aplicação de ultrassom e precipitação em não-solvente. As SNPs preparadas foram utilizadas como copolímero para formação de microgéis híbridos do tipo SNP-co-p(NIPAM) através de polimerização em emulsão na presença e na ausência de surfactante. A influência das SNPs nas propriedades dos microgéis foi estudada por MEV, DLS, PZ e SAXS, onde foram observadas mudanças no comportamento físico-químico e estrutura supramolecular dos microgéis. No geral, observaram-se deslocamentos da temperatura de transição de fase para valores maiores (até 35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro), aumento da estabilidade coloidal e organização dos polímeros presentes no microgel em uma arquitetura caroço-casca. As propriedades de inchamento dos microgéis também foram estudadas através da teoria de Flory-Rehner, onde a temperatura theta e o grau de polimerização entre dois pontos de reticulação foram determinados através do ajuste apropriado do parâmetro de interação (χ). Paralelamente, visando um sistema diferente do descrito acima, foi estudado um novo agente de reticulação baseado nos polímeros do amido, a amilose e a amilopectina. Para isso, os polímeros do amido que compõem as nanopartículas foram modificados para a utilização como agente de reticulação na síntese de microgéis de p(NIPAM). Nesta etapa, uma reação de substituição dos grupos hidroxila dos polímeros do amido foi realizada com o cloreto de acriloíla de forma a inserir insaturações na estrutura dos polímeros, para que estes fossem aplicados como reticulante. O sucesso da reação de modificação foi verificado através de RMN 1H e FTIR, no qual um maior grau de substituição foi obtido quando um tempo maior de reação foi empregado. Microgéis de p(NIPAM) foram então preparados através de polimerização em emulsão utilizando os reticulantes sintetizados. Observou-se a influência do grau de substituição e da concentração do reticulante nos microgéis, analisados por MEV, DLS e UV-Vis com controle de temperatura. As principais mudanças foram relativas à temperatura de transição de fase e tamanho dos microgéis. Utilizando o agente de reticulação com maior grau de substituição, foi possível deslocar a temperatura de transição de fase dos microgéis preparados para valores maiores (35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro). Observou-se também uma resposta mecânica da rede do microgel, que refletiu no tamanho das partículas, influenciada pela concentração dos agentes de reticulação e do grau de substituição. Quanto maior a concentração e o grau de substituição do agente de reticulação, maior a resistência ao intumescimento observado no microgel. / This thesis presents the studies regarding the synthesis and characterization of thermoresponsive microgels of N-isopropylacrylamide (NIPAM) and amylaceous-based macromolecules, which are systems still little explored in the literature. At first, starch nanoparticles (SNP) were prepared by nanoprecipitation, through dissolution of starch granules in DMSO/H2O, ultrasound application and non-solvent precipitation. SNPs were then used as copolymer in SNP-co-p(NIPAM) hybrid microgels synthesized by emulsion polymerization in the presence and absence of surfactant. The influence of SNPs in microgel properties were studied by SEM, DLS, ZP, and SAXS, where changes in the physicalchemical behavior and supramolecular structure were observed. Summing up, shifts in the phase transition temperature up to 35 °C, increased colloidal stability, and microgel polymers organization into a core-shell structure were observed. Microgels swelling behaviour were also studied by the Flory-Rehner theory, where the theta-temperature and the degree of polymerization between two crosslinker points were determined through interaction parameter (χ) fitting. In parallel, a new starch-based crosslinker was studied. For this purpose, starch polymers (amylose and amylopectin within the SNPs) were modified in order to use them as crosslinker in p(NIPAM) microgel synthesis. In this step, a substitution reaction in hydroxyl groups of SNP was carried out with acryloyl chloride, where double bonds were attached in polymers structure, making it suitable as a crosslinker. Reaction performances were evaluated through 1H NMR and FTIR. Then, p(NIPAM) microgels were prepared by emulsion polymerization using the crosslinker synthesized. The degree of substitution and the crosslinker concentration influence were verified and analyzed by SEM, DLS and UV-Vis with temperature control. The main observed changes were related to the phase transition temperature e microgels size. Using the crosslinker with higher substitution degree, it was possible the shift of the phase transition temperature to higher values (~35 °C). A mechanical response, observed trough microgels size, was found, driven by the crosslinker concentration and substitution degree. As higher the concentration and substitution degree of the crosslinker, higher was the swelling resistance observed in microgel structure.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-01T14:44:08Z No. of bitstreams: 2 Dissertação - Marília Araújo Silva - 2018.pdf: 2200990 bytes, checksum: 4c17a2631ef8a10e10ae7bf6dc2916d8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-01T14:45:02Z (GMT) No. of bitstreams: 2 Dissertação - Marília Araújo Silva - 2018.pdf: 2200990 bytes, checksum: 4c17a2631ef8a10e10ae7bf6dc2916d8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-10-01T14:45:02Z (GMT). No. of bitstreams: 2 Dissertação - Marília Araújo Silva - 2018.pdf: 2200990 bytes, checksum: 4c17a2631ef8a10e10ae7bf6dc2916d8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-07-27 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The culinary quality of rice still prevails as a determinant parameter in the selection of promising lines by genetic breeding programs. Rice cooker test is one of the methods most used by research and processing industries in evaluating the yield and texture of the cooked grains of cultivars released and / or new lineages under study. Normally, in the methodology, the homemade cooking is simulated and the sensorial test is carried out with a team of tasters selected and trained for this purpose, choosing those most promising lines. However, traditional sensory evaluation is a judicious and relatively time-consuming method, since it requires training, aptitude, people and product availability, and scales of classification of standardized attributes associated with instrumental scales whenever possible. An instrumental test for texture analysis of cooked rice that is standard, reliable, fast and reproducible and whose results are associated with sensorial evaluation is not yet available. The objective of this work was to adjust the scale of cooked rice texture notes in the sensorial analysis, through new standards and according to the sensitivity of the panel of tasters and demands of Brazilian industries. The objective of this study was to evaluate the grain quality of 55 rice genotypes with different levels of amylose by means of sensorial, physico-chemical and instrumental methods and to propose rules based on the association of laboratory data with the sensory data for validation of an application recently developed in free software, with the function of integrating the quality data and indicating the expected culinary quality for the sample. Prediction models for sensory evaluation were expanded through statistical methods such as multiple regression, polytomic logistic regression, and principal component analysis. The results showed that 70% of the parameters of the viscoamilographic profile were associated to the sensory analysis data, followed by 68% and 62% for the instrumental analysis of texture and for the combination of the amylose content and the gelatinization temperature of the samples, respectively. The results of the multiple regression showed a high predictive power, with four significant variables (pejity and instrumental hardness, peak viscosity and final viscosity), indicating a great association of these values with the sensorial test. The viscoamilographic measurements of RVA (peak viscosity, trough, final viscosity, setback and peak time) also presented high predictive power of the instrumental texture with 77% of the total variance explained by the two main components. From these data, it was possible to create value rules for the development of a free software application in the prediction of rice cooking quality. The parameters used and the prediction models used allowed the data from the instrumental tests to predict the most probable classification of the culinary quality, without the necessity of the sensorial test itself. / A qualidade culinária do arroz prevalece ainda como parâmetro determinante na seleção de linhagens promissoras pelos programas de melhoramento genético. O teste de panela ou cocção do arroz é um dos métodos mais utilizados pela pesquisa e indústrias de beneficiamento na avaliação do rendimento e textura dos grãos cozidos de cultivares lançadas e/ou novas linhagens em estudo. Normalmente simula-se, na metodologia, o cozimento caseiro e realiza-se o teste sensorial com equipe de provadores selecionados e treinados para este fim, elegendo aquelas linhagens mais promissoras. Contudo, a avaliação sensorial tradicional é um método criterioso e relativamente moroso, pois requer treinamento, aptidão, disponibilidade de pessoas e de produto e escalas de classificação de atributos padronizadas e associadas às escalas instrumentais, sempre que possível. Ainda não se tem um teste instrumental para análise de textura de arroz cozido que seja padrão, confiável, rápido e reprodutível e cujos resultados se associem à avaliação sensorial. O objetivo deste trabalho foi ajustar a escala de notas de textura de arroz cozido na análise sensorial, por meio de novos padrões e avaliar a qualidade de grãos de 55 genótipos de arroz com diferentes teores de amilose por meio de métodos sensorial, físico-químicos e instrumentais, e propor regras baseadas na associação dos dados laboratoriais com os dados sensoriais para validação de um aplicativo recentemente desenvolvido em software livre, com a função de integrar os dados de qualidade e indicar a qualidade culinária esperada para a amostra. Os modelos de predição para avaliação sensorial foram ampliados por meio de métodos estatísticos, como regressão múltipla, regressão logística politômica e análise de componentes principais. Os resultados mostraram que 70% dos parâmetros do perfil viscoamilográfico associaram-se aos dados da análise sensorial, seguidos de 68% e 62% para a análise instrumental de textura e para a combinação do teor de amilose e temperatura de gelatinização das amostras, respectivamente. Os resultados da regressão múltipla mostraram alto poder preditivo, sendo quatro variáveis significativas (pegajosidade e dureza instrumentais, pico de viscosidade e viscosidade final), indicando grande associação desses valores com o teste sensorial. As medidas viscoamilográficas do RVA (pico de viscosidade, trough, viscosidade final, setback e tempo de pico) também apresentaram alto poder preditivo da textura instrumental com 77% da variância total explicada pelas duas componentes principais. A partir desses dados, foi possível criar regras de valores para o desenvolvimento de um aplicativo em software livre na predição da qualidade culinária do arroz. Os parâmetros e os modelos de predição utilizados permitiram a partir dos dados dos testes instrumentais, prever a classificação mais provável da qualidade culinária, sem a necessidade do teste sensorial propriamente dito.

Afin d'étudier la diffusion et la libération de molécules de tailles inférieures dans un gel polymère, les coefficients d'auto-diffusion d'une série de polymères en étoile avec un noyau d'acide cholique et quatre branches de poly(éthylène glycol) (PEG) ont été déterminés par spectroscopie RMN à gradient de champ pulsé dans des solutions aqueuses et des gels de poly(alcool vinylique). Les coefficients de diffusion obtenus ont été comparés avec ceux des PEGs linéaires et dendritiques pour étudier l'effet de l'architecture des polymères. Les polymères en étoile amphiphiles ont des profils de diffusion en fonction de la concentration similaires à leurs homologues linéaires dans le régime dilué. Ils diffusent plus lentement dans le régime semi-dilué en raison de leur noyau hydrophobe. Leurs conformations en solution ont été étudiées par des mesures de temps de relaxation spin-réseau T1 du noyau et des branches. L'imagerie RMN a été utilisée pour étudier le gonflement des comprimés polymères et la diffusion dans la matrice polymère. Les comprimés étaient constitués d'amidon à haute teneur en amylose et chargés avec de l'acétaminophène (de 10 à 40% en poids). Le gonflement des comprimés, ainsi que l'absorption et la diffusion de l'eau, augmentent avec la teneur en médicament, tandis que le pourcentage de libération du médicament est similaire pour tous les comprimés. Le gonflement in vitro des comprimés d'un complexe polyélectrolyte à base d'amidon carboxyméthylé et de chitosane a également été étudié par imagerie RMN. Ces comprimés sont sensibles au pH : ils gonflent beaucoup plus dans les milieux acides que dans les milieux neutres en raison de la dissociation des deux composants et de la protonation des chaînes du chitosane. La comparaison des résultats avec ceux d'amidon à haute teneur en amylose indique que les deux matrices ont des gonflements et des profils de libération du médicament semblables dans les milieux neutres, alors que les comprimés complexes gonflent plus dans les milieux acides en raison de la dissociation du chitosane et de l'amidon. / In an effort to study the diffusion and release of small molecules in a polymeric system, the self-diffusion coefficients of a series of star polymers with a cholic acid core bearing four poly(ethylene glycol) (PEG) arms in aqueous solutions and gels of poly(vinyl alcohol) were determined by pulsed gradient spin-echo NMR techniques. The results have been compared with those of linear and dendritic PEGs to elucidate the effect of the architecture of the polymers. The amphiphilic star polymers show similar concentration-dependent diffusion behaviors in the dilute regime to their linear homologues. They diffuse more slowly in the semi-dilute regime than the linear PEGs due to the presence of the hydrophobic core. The conformation of the star polymers in the solutions was studied by measuring the T1 values of the core and the arms of the diffusants. NMR imaging was used to study the swelling of polymeric tablets and diffusion in the polymer matrix. The tablets investigated were made of cross-linked high amylose starch (CHAS) and loaded with acetaminophen (10, 20 and 40 wt%). The swelling, water uptake and diffusion in the CHAS network are faster at higher drug loading levels, while the drug release rates are similar among all the tablets. The in vitro swelling of the tablets made of a polyelectrolyte complex based on chitosan and carboxymethylated starch has also been studied by NMR imaging. These tablets showed pH-sensitive behavior. They swelled much more in acidic media than in neutral media due to dissociation of the two components and the protonation of the amino groups in the chitosan residues. The comparison of the results with those obtained with the CHAS tablets indicates that the two matrices have similar swelling and drug release profile in neutral media, while the complex tablets showed a greater extent of swelling in acidic media due the dissociation of the chitosan from the complex.