Made available in DSpace on 2014-10-09T12:43:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:00Z (GMT). No. of bitstreams: 0 / O látex de borracha natural foi formulado, radiovulcanizado e, em seguida, estabilizado radioliticamente (GAMATEX), para ser empregado na fabricação de artefatos de borracha utilizados na área médica. A eficiência de reticulação do látex, quando radiovulcanizado com raios gama, correlacionou-se matematicamente com a razão de concentração do sistema de radiosensibilizador (x1 = [An-B] / [KOH]) e com a dose de vulcanização (x2), apresentando alto grau de interação, segundo o seguinte modelo matemático: , onde representa a resistência à tração na ruptura. O processo RVNRL foi otimizado para baixas doses de vulcanização e altas concentrações de An-B. A resistência radioxidativa da borracha, obtida a partir do GAMATEX, foi atingida adicionando-se uma mistura de antioxidantes (45% BANOX S + 55% TNPP). Esta mistura apresentou um efeito sinérgico. O látex apresentou comportamento pseudoplástico com a ocorrência de tensão de escoamento. A taxa de desestabilização irreversível do látex foi diretamente proporcional à [An-B] e inversamente proporcional à [KOH]. O efeito pós-irradiação do látex ou a desestabilização reversível, ocorreu devido à presença de uma concentração residual de An-B que não reagiu. A irradiação melhorou a estabilidade coloidal do GAMATEX, devido ao aumento da tixotropia e da tendência newtoniana além da correlação entre o grau de consistência (k) e o índice pseudoplástico (n), de acordo com o modelo matemático . Este fato permite um tempo maior de estocagem do GAMATEX. A viscosidade relativa do látex correlaciona-se com a temperatura e com o teor da borracha seca conforme o modelo matemático: , onde rw é a razão (BS/100-BS). O látex radiovulcanizado coagulou à temperatura de –10ºC no sistema de refrigeração projetado. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Orientador: Fábio César Gozzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T06:35:23Z (GMT). No. of bitstreams: 1 Lima_TatianiBrenellide_M.pdf: 10987476 bytes, checksum: 5ef2abf84b79afba4ad901cc1e46c719 (MD5) Previous issue date: 2014 / Resumo: A espectrometria de massas (MS) tem sido bastante utilizada em analises de amostras biológicas, tornando uma ferramenta indispensável para pesquisas na área de proteômica. A ligação cruzada é um processo de união covalente entre dois átomos espacialmente próximas. A ligação cruzada acoplada a MS permite estudos estruturais de proteínas baseado nas restrições de distância determinadas pelos espécies inter- intra-moleculares ligadas entre as cadeias laterais de resíduos de aminoácidos. Essa técnica vem sendo bastante utilizada na análise de interação entre proteínas, entretanto, um aspecto pouco explorado é a analise estrutural de proteínas. O objetivo desse trabalho foi determinar as estruturas terciárias e quaternárias de proteínas de chaperonas moleculares de cana-de-açúcar ou proteínas de choque térmico (do inglês, sugarcane heat shock protein, SHsp) utilizando a técnica de ligação cruzada acoplada com MS e modelagem molecular. As restrições de distâncias obtidas pela ligação cruzada e o gráfico de Ramanchandran foram utilizados para validar as estruturas tridimensionais da SHsp70 e SHsp90 obtidas por modelagem por homologia. Informações adicionais de dinâmica e flexibilidade da SHsp90 foi obtida pela técnica de troca hidrogênio/deutério. As chaperonas moleculares são proteínas importantes presentes em células para evitar o enovelamento incorreto de outras proteínas e suas agregações. Em plantas, fatores que corroboram com a tolerância ao estresse ainda são pouco compreendidos, mas provavelmente as chaperonas moleculares desempenha um papel importante no controle aos danos desse organismo. Desse modo, caracterizar estruturas de Hsp de cana de açúcar é uma informação essencial para a compreensão do mecanismo deste acompanhante de ação. Os estudos estruturais baseados em ligação cruzada acoplada a MS e modelagem por homologia permitiu propor um modelo estrutural para SHsp90 e SHsp70 / Abstract: Mass spectrometry (MS) has been extensively used to analyze biological samples and has advanced as an indispensable tool for proteomics research. Cross-linking is the process of chemically joining two spatially close atoms by covalent bond. The chemical cross-linking coupled to MS allows structural studies of protein based on distance constrains determined by inter- and intra-molecular cross-link between side chains of amino acids residues. This technique has been normally used to analyze protein-protein interaction but is mostly unexplored for structural analysis of proteins. The aim of this work was to investigate tertiary and quaternary structure of sugarcane molecular chaperone or heat shock protein (SHsp) using chemical cross-linking coupled to MS and homology modeling. The distance constrains obtained by chemical crosslinking and Ramachandran plot were used to validate tridimensional structures of SHsp70 and SHsp90 that was predicted by homology modeling. Additional information about flexibility and dynamics of SHsp90 was obtained using hydrogen/deuterium exchange (HDX) coupled to MS. The molecular chaperones are important proteins present in cell that helps prevent incorrect folding of proteins and their aggregation. The stress tolerance in plants is still poorly understood, but heat shock proteins likely play a large role in the plant damage control machinery. Thereby, characterizing Sugarcane Hsp structures is essential information toward the understanding of this chaperone¿s mechanism of action. The structural study of molecular chaperones by chemical cross-linking coupled to MS and homology modelling allowed the generation of a structural model for SHsp90 and SHsp70 / Mestrado / Quimica Organica / Mestra em Química

Orientador: Fábio Cesar Gozzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T04:44:36Z (GMT). No. of bitstreams: 1 Fioramonte_Mariana_M.pdf: 6585272 bytes, checksum: 7fcc677288d272f3c92f3e3116d43fa5 (MD5) Previous issue date: 2012 / Resumo: Ligação cruzada acoplada à espectrometria de massas (MS) é uma técnica que permite a caracterização estrutural de proteínas e complexos proteicos, especialmente nos casos em que estes não são passíveis de serem analisados por técnicas de alta resolução. O experimento baseia-se na reação de uma proteína ou no complexo proteico com um reagente bifuncional (agente de ligação cruzada, ALC) seguido de análise proteômica shotgun por MS. Isso trás para a técnica todas as vantagens da MS, como alta sensibilidade, rapidez de análise e facilidade de uso. Somente resíduos de aminoácidos espacialmente próximos podem ser ligados covalentemente pelo ALC, de forma que os peptídeos contendo a ligação cruzada, identificadas por MS, servem como restrições de distância entre os aminoácidos na estrutura nativa da proteína ou complexo proteico. O conjunto de peptídeos contendo a ligação cruzada fornece, assim, um conjunto de restrições de distâncias entre os aminoácidos que pode ser utilizado para montar um modelo molecular da proteína ou do complexo. O objetivo principal deste trabalho foi a aplicação da técnica de ligação cruzada acoplada a espectrometria de massas no mapeamento da interação entre as proteínas quinase de adesão focal (FAK), através de seu domínio FERM, e miosina. Esse complexo proteico está envolvido na sinalização molecular para o processo de hipertrofia cardíaca. A hipertrofia cardíaca é considerada um mecanismo de adaptação do miocárdio em resposta a sobrecargas hemodinâmicas e está associada com risco de desenvolvimento de insuficiência cardíaca, arritmias e morte súbita. Estímulos mecânicos são considerados os principais ativadores primários das respostas que conduzem às alterações fenotípicas do miocárdio nas várias doenças cardíacas. A caracterização estrutural do complexo FAK/miosina ao nível molecular permitiu a criação de um modelo molecular deste complexo, que foi validado através de mutações na região de interação entre as proteínas. Esse modelo permite que se entenda o processo de sinalização da hipertrofia ao nível molecular / Abstract: Chemical cross-linking coupled with mass spectrometry (MS) is a technique that allows the structural characterization of proteins and protein complexes, especially when these proteins are not amenable to be analyzed by high resolution techniques. The experiment is based on ther eaction of a protein or protein complex with a bifunctional reagent (cross-linking agent, ALC) followed by shotgun proteome analysis by MS. This brings to the technique all the advantages of MS, such as high sensitivity, short analysis time and ease of use. Only spatially close amino acid residues can be covalently bound by the reagent, so that the cross-linked peptides, identified by MS, serve as distance constraints between amino acids in the native structure of the protein or protein complex. The set of cross-linked peptides thus provides a set distance constraints among amino acids that can be used to build a molecular model of the protein or complex. The main objective of this work was to apply the cross-linking technique coupled to MS to map the interaction between the proteins Focal Adhesion Kinase (FAK), through its FERM domain, and myosin. This protein complex is involved in molecular signaling of the cardiac hypertrophy process. Cardiac hypertrophy is considered an adaptative mechanism of the myocardium in response to hemodynamic overload and it is associated with risk of developing heart failure, arrhythmias and sudden death. Mechamical stimuli are considered the main activator of the primary responses that lead to phenotypic changes of the myocardium in many cardiac diseases. The structural characterization of the complex FAK/myosin at the molecular level has allowed the creation of a molecular model of this complex, which was validated by mutations in the region of interaction between the proteins. This model allows the understanding the signaling processes of hypertrophy at the molecular level / Mestrado / Quimica Organica / Mestra em Química

Abstract Type I collagen is the main connective tissue protein in vertebrates. The cross-linking and correct organisation of the molecules is crucial for the proper function of the tissue. Traditionally collagen cross-linking has been studied using chemical cross-link analyses. However, this does not distinguish between the collagen types or the location of the cross-link within the molecule. The focus in this work was to study the carboxyterminal telopeptide domain of type I collagen for the differently cross-linked forms. An immunochemical approach was used and a new immunoassay, SP4, was developed for the detection of immaturely cross-linked peptide forms. The differently cross-linked structures were purified and characterised from human bone by using SP4 together with the earlier developed ICTP assay for trivalently cross-linked C-terminal telopeptide form. It was found that the majority of the trivalent cross-links in the C-terminal telopeptide were presently unknown structures, other than pyridinoline. A non-cross-linked form of C-terminal telopeptide of α1-chain of type I collagen was also discovered in bone. The epitope of the ICTP assay was characterised and found to reside in the phenylalanine rich region of the ICTP peptide. MMP-9, but not cathepsin K, mediated breakdown of the collagenous matrix was found to produce a peptide detectable by the ICTP assay. Healthy human Achilles tendon comprises mainly of type I collagen. In ruptured Achilles tendons, an increased type III collagen content was found. Since the synthesis of type III collagen was not increased, it is postulated that the type III collagen must have accumulated over a long period of time indicative of a long-lasting microtraumatic process in the tendon before the total rupture occurred. The ICTP content was increased and the ratio of SP4 to ICTP decreased in calcified stenotic aortic valves suggesting a change in the molecular organisation and cross-linking towards the type found in human bone. The total collagen content was dramatically decreased in the calcified valves. Both in the Achilles tendons and in the aortic valves, the ICTP content was found to decrease with age with a concomitant increase in the variants of the C-terminal telopeptide structures detectable with the SP4 assay, pointing to a change in the molecular organisation of the collagenous matrix in these tissues.

Le cadre industriel de ce projet est de trouver une alternative à la résine phénol-formaldéhyde (RFP) et à son durcisseur, utilisée actuellement en pneumatique pour améliorer les performances aussi bien des compositions de caoutchouc que celles des produits semi-finis. Un des aspects essentiels de la pneumatique est d’augmenter la rigidité à faible déformation des pneus sans augmenter l'hystérésis des élastomères durcis chargés de noir de carbone. Ainsi, l'objectif de ce travail de thèse est de proposer un système thermodurcissable alternatif aux résines RFP actuelles. Ce nouveau système doit être riche en carbone renouvelable et doit être chimiquement modifié au moyen de procédés écologiques. La lignine a été choisie comme source de carbone renouvelable. Une étude préliminaire a souligné les potentialités d'une classe de lignines époxy pour l'application visée. Notre approche consiste en la conception de lignines modifiées par des époxy par une méthode originale évitant l'utilisation de l'épichlorhydrine suivie de son durcissement par des agents de réticulation appropriés. Des tests préliminaires avec un composé modèle de lignine ont donné la gamme des composés époxy et les conditions à tester pour la réaction avec la lignine. Les expériences avec la lignine ont alors confirmé le potentiel de l’ester diglycidylique de l’acide 4, 5-époxytetrahydrophthalique, un composé époxy contenant à la fois un groupement cycloaliphatique et deux types de groupements époxy glycidyliques, comme alternative à l'épichlorohydrine pour la préparation de lignines modifiées. Dans les conditions que nous avons définies, la réaction donne des prépolymères de type lignine-époxy sous forme de poudre avec un niveau d’époxydation de 1,2 mol/kg déterminé par spectroscopie FTIR. La série de tests effectuée sur des mélanges de caoutchouc a montré que la nouvelle lignine époxy associée à la p-xylylènediamine peut être mélangée avec succès avec le caoutchouc naturel et peut atteindre les propriétés de notre mix de référence. / The industrial framework of this project is the substitution of phenol formaldehyde resin (RFP) and its methyl donor hardener currently used for improving the performances of rubber compositions of tires or semi-finished products for tires. A critical aspect is the need for an increase of rigidity at low deformation without enhancement of the hysteresis of the cured elastomers filled with carbon black. The specific aim of this PhD work was to propose an alternative thermosetting system to the current RFP resins. This new system should be rich in renewable carbon and chemically modified by environmentally friendly processes. Lignin was chosen as the source of the renewable carbon. A preliminary study emphasized the potentialities of a class of epoxy-modified lignins for the targeted application. The main approach was the design of epoxy modified lignin to be obtained by an original method avoiding the use of epichlorohydrine and to be subsequently cured by appropriate cross-linkers. A preliminary screening with a lignin model compound gave the range of the epoxy compounds and the conditions to be tested for the reaction with lignin. Then various experiments with lignin confirmed the potential of 4, 5-epoxytetrahydrophthalic acid diglycidylester, an epoxy compound containing both one cycloaliphatic and two glycidyl type of epoxy groups, as an alternative for epichlorohydrine for the preparation of modified lignin. In the conditions we have defined, the reaction yielded epoxy lignin-based prepolymers as a powder with epoxy level as high as 1,2 mol/kg determined by FTIR spectroscopy. The series of evaluation campaigns in rubber blends showed that the new epoxy-modified lignin associated with p-xylylenediamine can be successfully mixed with natural rubber and enable to reach the properties of our reference mix.

The aim of this project was to analyse the cellular and biomechanical changes after collagen cross-linking (CXL) treatment on postmortem eye-banked human corneas using different UVA intensities and repeated treatments, and to explore the effects of standard collagen cross-linking on keratoconic corneal buttons, in-vitro. Preliminary studies were conducted to assess the feasibility of using eye-banked corneas to assess the effects of collagen cross-linking, and the possibility of applying scanning acoustic microscopy (SAM) to measure the speed of sound/elasticity of corneal tissue. Eye-banked human corneas were successfully cross-linked allowing the effects of CXL to be studied in-vitro and SAM was used effectively to determine the mechanical properties of corneal tissue at different depths. The results of two experiments comparing UVA intensity suggested that no statistically significant difference was found in the histological changes or in the induced stiffness after applying low and high intensity cross-linking on normal human corneas. However, the number of apoptotic cells was found to be significantly less but deeper into the posterior stroma in the high intensity cross-linked corneas. Collectively, these results confirmed the safety and efficacy of both techniques with the advantage of reducing the treatment time using the higher-intensity treatment. In another in-vitro study, keratoconic corneal tissue was used. Different histological and biomechanical outcomes were found between the cross-linked and control keratoconic tissue. The effects of cross-linking were found to penetrate deeper in the keratoconic tissue compared to in the normal corneal tissue found in previous studies. This could be due to the altered collagens and extracellular matrix of the keratoconic corneas, as they were taken from patients in advanced stages of the disease. This study confirmed the importance of having corneal thickness of at least 400μm after epithelial debriding to maintain the endothelial cell density and integrity. Finally, further cross-links were induced when collagen cross-linking treatment was repeated. However, repeating cross-linking three times a deeper cell death close to the endothelium was noticed which suggests that multiple treatments could be unsafe. Additionally, lower speed of sound than the cross-linking twice. This could be due to elimination of the induced cross-links by longer exposure to UVA irradiation. In conclusion, eye-banked human corneas were successfully used to evaluate the effects of cross-linking treatment and repeated treatment. Additionally, keratoconic corneal buttons were used to study the effects of collagen cross-linking in-vitro. This model of using eye-banked human corneas and keratoconic corneal tissue enabled us to study the effects of cross-linking treatment using different protocols and the effects of repeated treatment, and it could ultimately be used to compare the results with in-vivo studies.

Orientadores: Rosiane Lopes da Cunha, Ana Carla Kawazoe Sato / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Almentos / Made available in DSpace on 2018-08-18T17:56:49Z (GMT). No. of bitstreams: 1 Costa_AlineAlvaresdaSilva_M.pdf: 2383816 bytes, checksum: 2af9fcfd4c4efd286c4471da25aa7226 (MD5) Previous issue date: 2011 / Resumo: Proteínas são os biopolímeros mais amplamente utilizados nas formulações de emulsões alimentícias como agentes emulsificantes, por serem um aditivo seguro. Com o intuito de entender e melhorar as propriedades emulsificantes das proteínas, inicialmente foram estudadas as macroemulsões óleo-água (O/A) estabilizadas por caseinato de sódio (CN-Na), obtidas em um sistema rotor-estator, sob diferentes concentrações de proteína e condições de pH. Todas as macroemulsões apresentaram separação de fases, devido ao mecanismo de cremeação. Este processo de desestabilização foi reduzido quando existiu o aumento da viscosidade dos sistemas, obtido pela adição de maiores concentrações de proteína e pela redução do pH em direção ao ponto isoelétrico da proteína. Já a utilização da homogeneização a altas pressões promoveu a formação de emulsões cineticamente estáveis, não sendo observada separação de fases com 4% de CN-Na em nenhuma das condições de pH. De modo geral, as emulsões apresentaram comportamento pseudoplástico, com exceção das emulsões estabilizadas com 1% de proteína em pH 5, que se comportaram como fluido dilatante, e em pH 7, como fluido Newtoniano. A redução do pH para os sistemas com 1% de CN-Na levou à desestabilização das emulsões, devido à menor concentração de proteínas adsorvidas não permitirem uma estabilização eletrostática. Foi realizado um tratamento enzimático para melhorar a estabilização das emulsões que separaram de fases em pH ácido. Assim, géis de caseinato de sódio foram reticulados com lacase e ácido ferúlico e as propriedades mecânicas desses géis foram avaliadas. A adição de lacase mediada por ácido ferúlico resultou em géis mais rígidos, firmes e menos deformáveis. As melhores combinações foram selecionadas para o preparo de emulsões O/A estabilizadas com CN-Na com o objetivo de aumentar a estabilidade em pH ácido. O uso desse tratamento enzimático levou a modificações na estrutura da proteína e, com isso, mudanças nas suas propriedades funcionais, o que permitiu o aumento na estabilidade das emulsões. Em geral, essas emulsões tratadas enzimaticamente apresentaram-se mais estáveis, com distribuição de gotas menos polidispersa e com comportamento mais estruturado, apesar do aumento no diâmetro médio das gotas, variando entre 11,79 e 20,17 µm para emulsões em pH 3 contra 6,14 µm medido na emulsão controle (sem tratamento enzimático). Assim, o aumento na estabilidade dessas emulsões deve estar associado ao aumento da viscosidade, que promoveram estabilidade estérica aos sistemas. Portanto, os resultados mostram que foi possível a produção de emulsões ácidas com maior estabilidade a partir do caseinato de sódio, através do tratamento enzimático, originando emulsões com estruturas e propriedades reológicas diferenciadas em comparação com a proteína não reticulada / Abstract: Proteins are biopolymers widely used as a safe additive in the formulation of food emulsions as emulsifying agents. To understand and improve the emulsifying properties of sodium caseinate, initially oil-in-water macroemulsions (O/W) were studied. The emulsions were stabilized by sodium caseinate prepared using a rotor-stator device at different concentrations of protein and pH. All macroemulsions showed phase separation due to the creaming mechanism. This mechanism of destabilization was reduced with the increase of system viscosity, either due to the increase on the concentrations of protein and by the reduction of pH towards to the protein¿s isoelectric point. The use of high-pressure homogenization promoted the formation of stable microemulsions, with no phase separation observed in emulsions with 4% CN-Na. In general, the emulsions exhibited a shear-thinning behavior, except the emulsion containing 1% protein at pH 7, which exhibited Newtonian behavior, and at pH 5, which tended to show a shear-thickening behavior. The reduction of pH in emulsions with 1% CN-Na led to phase separated emulsions, which was attributed to the amount of adsorbed protein, which was insufficient to promote a strong electrostatic repulsion. In order to improve the stabilization of phase separated emulsions at acidic pH, an enzymatic treatment was carried out. Thus, sodium caseinate gels were crosslinked with laccase and ferulic acid and the mechanical properties of these gels were evaluated. The addition of laccase and ferulic acid resulted in gels with increased hardness, firmness and less deformable. The best treatments were selected for the preparation of O/W emulsions stabilized with CN-Na, in order to increase in their stability in acidic pH. The enzymatic treatment caused modifications in the protein structure, resulting in changes of functional properties, which led to an increase in the emulsion stability. In general, these enzymatically treated emulsions were more stable, composed by droplets with lower size distribution and more structured behavior, despite the increased mean droplet diameters (between 11.79 and 20.17 µm for emulsions at pH 3). Thus, the stability increase of these emulsions could be associated to the increase in viscosity, which resulted in steric stability. Results showed that it was possible to produce more stable emulsions containing sodium caseinate in acidic pH using enzymatic treatment, resulting in emulsions with different structures and rheological properties when compared with the non-cross-linked protein / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

Orientador: Flavia Maria Netto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T13:49:46Z (GMT). No. of bitstreams: 1 Fernandes_MicheleAugusto_M.pdf: 2050778 bytes, checksum: aedc46d9b78bf413f7e34cfbe46a36a6 (MD5) Previous issue date: 2009 / Resumo: A ß-Lactoglubulina (ß-Lg) é uma das proteínas mais antigênicas presente no leite bovino. Tratamentos físicos, químicos ou enzimáticos podem alterar a antigenicidade desta proteína. Em trabalho anterior, verificou-se que o potencial antigênico da ß-Lg é reduzido quando polimerizada pela enzima transglutaminase (TG) na presença de cisteína (Cys). No entanto, o efeito da polimerização sobre o valor nutricional da ß-Lg ainda não é conhecido. O presente estudo teve como objetivo avaliar o efeito da reação de polimerização catalisada pela TG na digestibilidade in vitro e atividade antigênica da ß-Lg antes e após a ação das enzimas gastrintestinais. A ß-Lg polimerizada pela TG (0, 10 ou 25 U g-1), após tratamento térmico ou na presença de agentes redutores Cys (0, 0,1 e 0,25 mol L- 1) ou ditiotreitol (DTT 0,02 mol -1), foi avaliada quanto à digestibilidade in vitro, utilizando as enzimas pepsina e pancreatina. As amostras, antes e após a digestão in vitro, foram caracterizadas pelos métodos SDS-PAGE, SDSPAGE/ tricina e cromatografia líquida de alta eficiência de fase reversa (CLAE-FR). Posteriormente, as amostras foram avaliadas quanto à antigenicidade, exceto aquelas na presença de DTT, por meio do método de Imunoblote, utilizando soro de camundongos BALB/c sensibilizados com a ß-Lg na forma nativa (ß-Lg N) ou com ß-Lg polimerizada com 25 U de TG g-1, na presença de 0,25 mol L-1 de Cys (ß-Lg 0,25Cys 25TG). A adição de TG resultou na formação de polímeros com massa molar igual ou acima de 97,4 kDa, principalmente na presença de agentes redutores alcançando aproximadamente 96% de polimerização na presença de DTT e 91% na presença de Cys. A digestibilidade in vitro da ß-Lg N foi 53,6% e todos os tratamentos realizados aumentaram a digestibilidade da proteína em até 79%. Os maiores valores de digestibilidade foram obtidos quando a ß-Lg foi tratada com agentes redutores. O processo de polimerização também teve efeito positivo na digestibilidade, principalmente para as amostras polimerizadas na presença de Cys ou DTT, atingindo valores acima de 75%. A análise por Imunoblote mostrou que a polimerização da ß-Lg na presença de agente redutor Cys, na concentração de 0,25 mol L-1, reduziu o reconhecimento da ß-Lg pelas IgE específicas presente nos soros dos animais sensibilizados com ß-Lg N ou com ß- Lg 0,25Cys 25TG. Após a digestão com pepsina e pancreatina, as amostras polimerizadas pós-tratamento térmico ou na presença de Cys apresentaram redução da antigenicidade, como também os digeridos da ß-Lg tratada com Cys (não polimerizada com TG). A desnaturação pelo agente redutor Cys e a polimerização por TG em ambas as condições estudadas mostraram ser métodos efetivos no aumento da digestibilidade da ß-Lg. Por sua vez, a combinação destes métodos com a digestão por enzimas gastrintestinais levou à redução da antigenicidade da proteína, já que os peptídeos gerados apresentaram potencial antigênico baixo / Abstract: The ß-Lactoglubulin (ß-Lg) is one of the most antigenic proteins present in the bovine milk. Physical, chemical or enzymatic treatments can alter the antigenicity of this protein. In previous study, it was shown that the antigenic potential of ß-Lg is reduced when polymerized by transglutaminase (TG) in the presence of cysteine (Cys). However, the effect of polymerization on the nutritional properties of ß-Lg is still unknown. The present study aimed to evaluate the effect of the polymerization reaction catalyzed by TG on the in vitro digestibility and the antigenic activity of ß- Lg, before and after simulate digestion with gastrointestinal enzymes. The in vitro digestibility of the ß-Lg treated with TG (0, 10 or 25 U g-1), after heat treatment or in the presence of reducing agents Cys (0, 0.1 and 0.25 mol L-1) or dithiothreitol (DTT 0.02 mol L-1), was evaluated using the gastrointestinal enzymes, pepsin and pancreatin. The samples, before and after in vitro digestion, were characterized by SDS-PAGE, SDS-PAGE/tricine and reversed-phase high performance liquid chromatography (RP-HPLC). Subsequently, the samples were evaluated for antigenicity, except those prepared in the presence of DTT, by immunochemical methods (Immnoblotting), using sera from BALB/c mice sensitized with native ß-Lg (ß-Lg N) or ß-Lg polymerized with 25 U of TG g-1 in the presence of 0.25 mol L-1 of Cys (ß-Lg 0.25Cys 25TG). The formation of polymers with molar mass equal to or above 97.4 kDa was observed with the addition of TG, especially in the presence of reducing agents, reaching approximately 96% of polymerization in the presence of DTT and 91% in the presence of Cys. The in vitro digestibility of native ß-Lg was 53.6% and the all treatments performed increased the digestibility of protein up to 79%. The highest values of digestibility were obtained in the presence of reducing agents. The polymerization also had a positive effect on the digestibility, especially for those samples polymerized in the presence of Cys or DTT, with values above 75%. Analysis by immunoblotting showed that the polymerization of ß-Lg in the presence of 0.25 mol L-1 Cys, reduced the recognition of ß-Lg specific IgE present in the sera of animals sensitized with ß-Lg N or ß-Lg 0.25 Cys 25TG. After digestion with pepsin and pancreatin, the samples polymerized after heat treatment or in the presence of Cys showed reduced antigenicity. The digest of the samples treated with Cys (not treated with TG) was not recognized as antigens. The denaturation by Cys and polymerization by TG in both conditions were effective in increasing the digestibility of ß-Lg. In turn, the combination of these methods with digestion by gastrointestinal enzymes led to reduction of antigenicity of the protein and that peptides generated showed low antigenic potential / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição

Cellulose nanofibrils are a biobased and renewable material with potential to be used in many different applications. Such applications include air filtration, absorption of liquids, and thermal insulation.  To be used for these applications the cellulose nanofibrils must form a porous and dry material. However, maintaining some degree of porosity after drying is difficult, since the fibrils are extracted in liquid and tend to collapse into a dense material upon drying. Certain methods have proven effective for making a dry porous material from cellulose nanofibrils, but these are often expensive and not suitable for large scale production. The aim of this project is to test possible methods for making a highly porous cellulose nanofibril-based material. These methods must be environmentally sustainable and suitable for large scale production. An extensive screening has been conducted with the aim of identifying methods resulting in materials with high porosity. The obtained materials have been analysed further to give a more thorough understanding of the porosity as well as other characteristics. The results indicate that cross-links in the material strengthen the structure, and that drying samples from water always results in complete collapse or very dense materials while drying samples from certain solvents other than water results in more porous materials. The analysed materials had very different porosities, some of which were relatively high. The most porous material analysed by Brunauer-Emmett-Teller gas adsorption had a surface area of 9.5 m2/g. This project gives insight into how cross-linking chemistries and treatment with different solvents and pH affect the resulting cellulose nanofibril-based material, as well as knowledge about which methods can be used to successfully produce dry porous cellulose nanofibril-based materials.