David Richard Walker’s Metrology of the Roman Silver Coinage analyzed the silver content of over 5000 Roman denarii, antoniniani, and drachmae using x-ray fluorescence (XRF) spectrometry. His results have been widely cited and used by scholars in the fields of Roman economic theory and numismatics. This thesis seeks to prove that Walker’s XRF results were not only inaccurate, but inconsistently so. Corrosion and surface enrichment on silver-copper coins have caused surface-level elemental examinations, like XRF, to produce incorrect results. The results from Walker’s XRF analysis have been compared against results from four individual wet chemical studies. The comparisons display striking, and significant, differences. I am forced to conclude that Walker’s data does not in any way align with the true silver content of the coins he analyzed. As a result, this thesis will re-examine several theories and hypotheses posed by scholars who used Walker’s data and propose new, more appropriate, uses for Walker and XRF analysis outside of the examination of corroded silver-copper coins.

Made available in DSpace on 2014-06-11T19:31:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-02-19Bitstream added on 2014-06-13T18:42:02Z : No. of bitstreams: 1 hidalgodeandrade_le_dr_arafo.pdf: 695382 bytes, checksum: 22a8c2dd7f2e65095f107f6a8bae0d0d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A utilização de corantes fluorescentes tem ajudado ao estudo da penetração de sistemas adesivos na estrutura dental e alguns compósitos, bem como na avaliação da microinfiltração e fendas na interface dente restauração. No caso das resinas compostas, esta técnica pode ser útil na verificação da profundidade de polimerização e vulnerabilidade físico-química das mesmas a corantes orgânicos. Neste intuito, nos propusemos a avaliar por meio de espectroscopia de fluorescência, a difusão de um corante orgânico em resinas compostas em função dos fatores: 1. Tipo de resina, 2. Fonte de luz, 3. Tempo de polimerização e 4. Tempo de imersão no corante. Para isso, foram realizados 2 grupos experimentais de acordo com a fonte de luz: lâmpada halógena- Grupo H e sistema LEDs - Grupo L. Cada grupo foi subdividido de acordo com a resina utilizada: 1. Micropartícula (Filtek A110/ 3M), 2. Híbrida (Z100/ 3M) e 3. Compactável (P60/ 3M), onde cada subgrupo teve 2 tempos de polimerização: 40 e 60 segundos, e 3 tempos de imersão em solução de Rodamina 6G a 0,1% em etilenoglicol: 0, 24 e 48 horas. Cada subgrupo possuía 5 amostras de 4 mm de diâmetro e 4 mm de espessura. Completados os tempos de imersão, foi obtida 1 fatia de 1,5 mm de espessura de cada amostra, para traçar o perfil espacial de fluorescência e calcular o coeficiente de difusão. Os resultados mostraram que a resina híbrida obteve os menores valores de difusão quando comparada com as outras. Além disso houve uma tendência da difusão diminuir com o aumento do tempo de imersão de 24 para 48 horas, bem como com o aumento do tempo de polimerização de 40 para 60 segundos. A lâmpada halógena determinou difusão significantemente menor nos corpos de prova quando comparado com o sistema LEDs, independente do tipo de resina utilizada. Com isto, podemos concluir que a difusão de corante... . / The fluorescent markers have been used to assess the teeth and composites bonding systems penetration, microleakeage and teeth-restoration interface gaps. This markers also can be used to verify the resin deep polimenization and organic dyes susceptibility. In this work, the fluorescence spectroscopy was used to assess an organic dye difussion on composite resins, considering: 1- resin type, 2- light source, 3- polimerization time and 4- dye immersion time. The experimental groups of Halogen lamp (group H) and LEDs system (group L) were sub-divided according to resin type: 1- microfilled (FilteK A110/3M), 2- hybrid (Z100/3M) and 3- packable (P60/3M) with 40 and 60 seconds of polimerization time, three immersion times on ethylene glycol rhodamine 6G 0.1% solution: 0, 24 and 48 hours, with 5 specimens for each sub-group (4 mm of diameter and thickness). Once completed the immersion times, one 1.5 mm slice was obtained for each specimen and spatial fluorescence profile was traced to calculate a difussion coeficient. The results shown that, compared to other resins, an hybrid resin has the lowest difussion values. When the immersion time was increased of 24 to 48 hours and polimerization time of 40 to 60 seconds, a difussion decrease tendency was observed. The specimens cured by halogen lamp shown significantly lower difussion than that cured by LEDs system, independent of resin type. We can conclude that dye difussion into resin mass was influencied by the same factors that affect the polimerization, and when lower polimerization was present, more quickly will be the dye difussion.

Made available in DSpace on 2014-06-11T19:31:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-17Bitstream added on 2014-06-13T19:20:26Z : No. of bitstreams: 1 gaiao_u_dr_arafo.pdf: 721993 bytes, checksum: f5fc596fed638936262956e5eebcb630 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi avaliar o efeito do manchamento sobre a intensidade de fluorescência de resinas compostas, em função dos meios de imersão e do tempo. Para isso, foram selecionadas as seguintes resinas compostas: Filtek Supreme XT (3MESPE), 4 Seasons (Ivoclar Vivadent), Venus (Heraeus – Kulzer), Vit~l~escence (Ultradent) e Esthet-X (Dentsply). Foram selecionadas também as seguintes soluções: café, suco de laranja, refrigerante de cola, vinho tinto e saliva (controle). Para cada condição experimental foram confeccionados cinco corpos-deprova (n=5) em forma de disco medindo 10,0mm de diâmetro e 1,0mm de espessura, que permaneceram imersos em saliva artificial e mantidos em estufa a uma temperatura de 37ºC±1. Esses corpos-de-prova foram retirados da estufa três vezes ao dia para imersão nas soluções testadas, durante o período de cinco minutos. Após este período foram lavados em água corrente e novamente imersos em saliva artificial e mantidos em estufa, até o momento da mensuração da intensidade de fluorescência. As leituras foram realizadas em seis níveis de variação: T0 - após confecção dos corpos-de-prova sem imersão em saliva artificial; T1 - 24 horas após imersão em saliva artificial; T2 - 24 horas após imersão nas soluções; T3 - 07 dias após imersão nas soluções; T4 - 14 dias após imersão nas soluções e T5 - 21 dias após imersão nas soluções. Para a obtenção dos valores de intensidade de fluorescência foi utilizado um espectrofotômetro (Spex Triax Fluorolog 3) calibrado para que o raio incidente fosse emitido com um comprimento de onda de 390nm e para que todo o fenômeno de fluorescência fosse registrado em uma faixa compreendida entre 400nm e 700nm. Os resultados obtidos foram submetidos à Análise de Variância e ao Teste de Tukey a 5%. De acordo com os resultados observou-se que as soluções influenciaram... / The aim of this study was to evaluate the effect of staining on the fluorescence intensity of composite resins, depending on the solutions and immersion time. The following composites were selected: Filtek Supreme XT (3MESPE), 4 Seasons (Ivoclar Vivadent), Vênus (Heraeus – Kulzer), Vit~l~escence (Ultradent) and Esthet-X (Dentsply). We also selected the following solutions: coffee, orange juice, cola soft drink, red wine and artificial saliva (control). For each experimental condition were made five specimens (n=5) in a disk shape measuring 10,0mm diameter and 1,0mm thickness. All the specimens were immersed in artificial saliva and kept in an incubator at a temperature of 37ºC±1. The specimens were removed from the incubator three times a day for immersion in the solutions tested, during the period of five minutes. After it was washed in running water and again immersed in artificial saliva, until the time of measurement of fluorescence intensity. The readings were taken at six levels of variation. T0 - 24 hours after preparing the specimens, T1 - 24 hours after immersion in artificial saliva, T2 - 24 hours after immersion in the solutions, T3 after seven days, T4 after fourteen days and T5 after 21 days. To obtain the values of fluorescence intensity, was used a calibrated spectrophotometer (Spex Triax Fluorolog 3) with an incident ray delivered with a wavelength of 390nm. The phenomenon of fluorescence was registered between 400nm and 700nm. The results were submitted to the analysis of variance and Tukey's test 5%. The results showed that the solutions influenced the intensity of fluorescence emitted by resin composites (p<0,05). Coffee was the higher staining solution, followed by red wine, orange juice, cola soft drink and artificial saliva. Regarding the time it was noted that after T2 there was a significant change in fluorescence emission... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:33:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:44:37Z : No. of bitstreams: 1 goncalves_sfm_dr_araca.pdf: 1213188 bytes, checksum: c60aab36aac67d006cedba20e5396fe8 (MD5) / As lesões cariosas de superfícies proximais se destacam por sua grande incidência, tanto pelo fato da região propiciar o acúmulo de biofilme bacteriano, quanto pelas dificuldades de higienização e de diagnóstico precoce. O objetivo deste estudo foi avaliar a performance da inspeção visual + sondagem (IV+S), laser de fluorescência (L), radiografia interproximal (RXI), separação dental + inspeção visual + sondagem (SD+IV+S) e separação dental + laser de fluorescência (SD+L) no diagnóstico de lesões cariosas proximais sem e com cavitação. Foram examinadas, por 2 profissionais, 167 superfícies de 30 pacientes de faixa etária entre 4 e 12 anos de idade, utilizando-se os 5 tipos de exames. Como método de validação para lesões cariosas com cavitação foi utilizada a dupla impressão das áreas interproximais com silicona de condensação. Em relação às lesões cariosas sem cavitação, os valores médios de sensibilidade encontrados para os exames de IV+S, L, RXI, SD+IV+S e SD+L foram de 44%, 33%, 49%, 100% e 48%, respectivamente. Em relação às lesões cariosas com cavitação, a sensibilidade foi de 15%, 40%, 59%, 59% e 41%, respectivamente. A correlação dos métodos de diagnóstico, em relação às lesões cariosas com cavitação, sugeriram uma maior precisão para a SD+IV+L. Os resultados sugeriram que a utilização da separação dental aumenta o desempenho no diagnóstico de lesões cariosas proximais, e que o método de impressão com silicona pode ser indicado como um método auxiliar definitivo de diagnóstico de lesões com cavitação. / The approximals carious lesions stand out for its great incidence, so much for the fact of the area to propitiate the accumulation of bacterial plaque, as for the difficulties of toothbrushing and of precocious diagnosis. The objective of this study went evaluate the performance of the visual inspection + probing (IV+P), laser fluorescence (LF), bitewing radiographs (BW), dental separation + visual inspection + probing (SD+IV+P) and dental separation + laser fluorescence (SD+L) in the diagnosis of approximals carious lesions without and with cavitation. 167 surfaces of 30 patient of age group between 4 and 12 years were examined for 2 professional being used the 5 types of exams. As validation method for cavitated carious lesions were the double impression of the interproximals areas with condensation-cure silicone impression material. In relation to the carious lesions without cavitation, the medium values of sensibility found for the exams of IV+P, LF, BW, SD+IV+P and SD+LF were of 44%, 33%, 49%, 100% and 48%, respectively. In relation to the cavitated carious lesions , the sensibility was of 15%, 40%, 59%, 59% and 41%, respectively. The results suggested that the use of the dental separation increases the effectiveness in the diagnosis of approximal carious lesions, and the impression method can be indicated as a definitive auxiliary method of diganosis of lesions cavitated.

abstract: Identification of early damage in polymer composite materials is of significant importance so that preventative measures can be taken before the materials reach catastrophic failure. Scientists have been developing damage detection technologies over many years and recently, mechanophore-based polymers, in which mechanical energy is translated to activate a chemical transformation, have received increasing attention. More specifically, the damage can be made detectable by mechanochromic polymers, which provide a visible color change upon the scission of covalent bonds under stress. This dissertation focuses on the study of a novel self-sensing framework for identifying early and in-situ damage by employing unique stress-sensing mechanophores. Two types of mechanophores, cyclobutane and cyclooctane, were utilized, and the former formed from cinnamoyl moeities and the latter formed from anthracene upon photodimerization. The effects on the thermal and mechanical properties with the addition of the cyclobutane-based polymers into epoxy matrices were investigated. The emergence of cracks was detected by fluorescent signals at a strain level right after the yield point of the polymer blends, and the fluorescence intensified with the accumulation of strain. Similar to the mechanism of fluorescence emission from the cleavage of cyclobutane, the cyclooctane moiety generated fluorescent emission with a higher quantum yield upon cleavage. The experimental results also demonstrated the success of employing the cyclooctane type mechanophore as a potential force sensor, as the fluorescence intensification was correlated with the strain increase. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2014

abstract: Fluorescence spectroscopy is a powerful tool for biophysical studies due to its high sensitivity and broad availability. It is possible to detect fluorescence from single molecules allowing researchers to see the behavior of subpopulations whose presence is obscured by “bulk” collection methods. The fluorescent probes used in these experiments are affected by the solution and macromolecular environments they are in. A misunderstanding of a probe’s photophysics can lead researchers to assign observed behavior to biomolecules, when in fact the probe is responsible. On the other hand, a probe’s photophysical behavior is a signature of the environment surrounding it; it can be exploited to learn about the biomolecule(s) under study. A thorough examination of a probe’s photophysics is critical to data interpretation in both cases and is the focus of this work. This dissertation investigates the photophysical behavior of symmetric and asymmetric cyanines in a variety of solution and biomolecular environments. Using fluorescent techniques—such as time-correlated single photon counting (TCSPC) and fluorescence correlation spectroscopy (FCS)—it was found that cyanines are influenced by the local environment. In the first project, the symmetric cyanines are found to be susceptible to paramagnetic species, such as manganese(II), that enhance the intersystem crossing (ISC) rate increasing triplet blinking and accelerating photobleaching. Another project found the increase in fluorescence of Cy3 in the protein induced fluorescence enhancement (PIFE) technique is due to reduced photoisomerization caused by the proximity of protein to Cy3. The third project focused on asymmetric cyanines; their photophysical behavior has not been previously characterized. Dy630 as a free dye behaves like Cy3; it has a short lifetime and can deactivate via photoisomerization. Preliminary experiments on Dy dyes conjugated to DNA show these dyes do not photoisomerize, and do not show PIFE potential. Further research will explore other conjugation strategies, with the goal of optimizing conditions in which Dy630 can be used as the red-absorbing analogue of Cy3 for PIFE applications. In summary, this dissertation focused on photophysical investigations, the understanding of which forms the backbone of rigorous fluorescent studies and is vital to the development of the fluorescence field. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2017

Background: SF processing has been firstly applied on the processing and storage of the rhizome of Dioscareapersimilis Prain et Burkill. in Wenxian country since 1900. Due to the simple, quick and low-cost characteristics of SF, it soon became a common postharvesting method for CMMs. However, recent studies showed that SF can either cause chemical changes to CMMs or affect human health. The awareness of identification of sulfur-fumigated CMMs is arisen. Comparing with chemical methods, FM is more simple and user-friendly to be established in authentication. Also, recent studies showed that different chemical profiles of CMMs can emit fluorescence differently. This research aimed to validate if FM was suitable for identification of sulfur-fumigated CMMs through using Codonopsis Radix and Ginseng Radix as examples. Method: 16 herbal samples were collected in different commercial market in different time, in which 6 of them was Codonopsis Radix and 8 of them was Ginseng Radix. Firstly, their chemical profiles of the samples were analyzed by UHPLC-QTOF-MS to make a chemical authentication. Then, their fluorescence characteristic were localized and captured on their transverse sections. Result: All the samples of Codonopsis Radix and 2 samples of Ginseng Radix were confirmed to be sulfur-fumigated as compounds sulfates or sulfites were detected. Investigated by fluorescence, herbal samples emitted blue and yellow fluorescence in different intensity under blue and green light filter. The fluorescence of groups of laticiferous tubes and resin canals were remarkable in Codonopsis Radix and Ginseng Radix respectively. Sulfur-fumigated samples showed similar characteristic to those raw samples. It was significant that samples of Codonopsis Radix emitted fluorescence differently even all of them were sulfur-fumigated. Conclusion: In the present study, samples with different growing condition, storage time and SF processing had some variation in their fluorescence characteristics. The result showed that fluorescence microscopy was not probable for identification of the sulfur-fumigated CMMs. The application of FM on the identification of sulfur-fumigated CMMs should be further investigated comprehensively. Key works: sulfur-fumigation; Codonopsis Radix; Ginseng Radix; authentication; fluorescence microscopy; UHPLC-QTOF-MS 背景：硫磺薰蒸中藥技術是在1900年由溫縣人民發明並最早記載於河南溫縣縣誌的。由於硫磺薰蒸技術擁有最高效，低成本，便於操控的優點，因此一直被藥農及中藥開發藥廠用於中藥防蟲及乾燥加工。但近年不少論文開始報道有關硫磺對中藥材的危害性，其中以硫磺薰蒸會影響中藥材內部的化學成分和藥理活性的報告最令人擔憂。礙於高效液相色譜法(HPLC)等化學檢測手段的複雜性，使用化學手段鑒別硫磺熏蒸藥材存在困難及難以普及。而近年實驗證明，中藥材裏不同的化學成分在熒光顯微鏡下會發放出不同熒光顔色。本研究以人參和黨參為例子，為應用熒光顯微鏡鑒別硫磺熏蒸中藥材，提供科學證據支持。 實驗方法：本研究採集了6個黨參及8個人參樣品進行分析。實驗首先以高效液相色譜-四極杆飛行時間串聯質譜(UHPLC-QTOF/MS)技術分析各樣品的化學成分用於鑒別樣品有否被硫磺熏蒸。然後各樣品先進行冷凍切割，並在熒光顯微鏡下進行橫切面觀察，從外到内觀察各特徵結構的熒光顔色，比較不同樣品的熒光差別。 結果：實驗結果顯示所有黨參樣品及2個白皮參樣品存在硫磺熏蒸后產生的硫酸鹽或亞硫酸鹽化合物，提示該樣品被硫磺熏蒸。所有樣品在熒光顯微鏡下都顯示不同程度的藍色及綠色熒光。儘管所有黨參樣品均被硫熏，但其顯示的熒光仍存在明顯差異，其中以樣品5和6最爲明顯。而被硫熏的人參樣品，其熒光則非常類似於非硫熏樣品。非硫熏的人參其熒光仍存在個體差異，其中2個樣品的熒光強度較其他為強及明顯。黨參内的乳管群及人參内的樹脂道，其熒光強度及顔色最爲突出。 結論：研究結果表明不同來源的樣品，其熒光特徵存在區別。熒光顯微鑑定技術不能有效鑒別市場上的黨參和人參是否經過硫磺熏蒸。熒光顯微鑑定硫磺熏蒸中藥方面的應用有待深入及系統探討。 關鍵詞：硫磺熏蒸；黨參；人參；熒光顯微鏡；中藥鑒別；高效液相色譜-四極杆飛行時間串聯質譜(UHPLC-QTOF/MS)

Compostos orgânicos podem ser liberados dos materiais resinosos, mesmo após sua polimerização, como resultado da presença de monômeros residuais e do processo de degradação do próprio material, podendo ocasionar efeitos citotóxicos, genotóxicos e alergênicos. O objetivo do presente estudo, in vitro, foi avaliar a liberação de compostos orgânicos de dois materiais resinosos, recentemente lançados no mercado, que apresentam inovações em suas formulações (resinas Kalore TM - GC FUJI e FiltekTM Silorane - 3M ESPE), variando a fonte de luz polimerizadora (halógena ou LED), a solução de imersão (água ou saliva artificial) e o pH da solução de imersão (7 ou 4,5). Foram confeccionados 56 corpos de prova da resina Kalore TM e 56 da resina FiltekTM Silorane, sendo 28 polimerizados com luz halógena e 28 com luz LED. Após aleatorização, 7 corpos de prova de cada resina foram armazenados em água com pH neutro, 7 em água com pH ácido, 7 em saliva com pH neutro e 7 em saliva com pH ácido. A leitura dos espectros das soluções foi realizada por meio da espectroscopia de fluorescência após 1, 3, 24, 48, 72, 168, 216, 312, 432, 504 e 672 horas. Após 672 horas, ainda verificou-se a liberação de compostos orgânicos das resinas KaloreTM e FiltekTM Silorane em todas as condições avaliadas. A liberação de compostos orgânicos foi menor nos grupos experimentais polimerizados pela luz LED. A quantidade de compostos orgânicos liberados foi menor nas amostras imersas em saliva. A resina KaloreTM liberou uma quantidade maior de compostos orgânicos em pH neutro, independente do meio de imersão. A resina FiltekTMSilorane liberou uma quantidade maior de compostos orgânicos em pH ácido, quando imersas em água, e uma maior quantidade de compostos orgânicos em pH neutro, quando imersas em saliva. A resina FiltekTMSilorane liberou mais de um componente orgânico. A espectrometria de fluorescência permitiu avaliar a liberação de compostos orgânicos das resinas KaloreTM e FiltekTM Silorane. / Organic compounds may be released from the resin materials, even after polymerization, as a result of the presence of residual monomers and degradation of the material itself, which may cause cytotoxic, genotoxic and allergenics effects. The purpose of this study, in vitro, was to evaluate the release of organic compounds from two resin materials, recently launched on the market, that present innovations in their formulations (resins KaloreTM - GC FUJI and FiltekTM Silorane - 3M ESPE), varying the source curing light (LED or halogen), the immersion solution (water or artificial saliva) and the pH of the immersion solution (7 or 4.5). Were prepared 56 specimens resin KaloreTM and 56 resin FiltekTM Silorane, 28 polymerized with halogen light and 28 with LED light. After randomization, 7 samples of each resin were immersed in water at neutral pH, 7 in water at acid pH, 7 in the saliva at a neutral pH, and 7 in the saliva at acid pH. The reading of the spectra of the solutions was performed by fluorescence spectroscopy at 1, 3, 24, 48, 72, 168, 216, 312, 432, 504 and 672 hours. After 672 hours, there was still release of organic resins KaloreTM and FiltekTM Silorane under all conditions evaluated. The release of organic compounds was lower in the experimental groups polymerized by LED light. The amount of organic compounds released was lower in samples immersed in saliva. The resin KaloreTM released more organic compounds at neutral pH in both immersion media. The resin FiltekTMSilorane immersed in water released more organic compounds at acid pH, but when the resin was immersed in saliva the release of organic compounds was higher at neutral pH. The resin FiltekTMSilorane released more that one organic component. The fluorescence spectrometry allowed us to evaluate the release of organic compounds resins KaloreTM and FiltekTMSilorane.

Made available in DSpace on 2014-06-11T19:23:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04-28Bitstream added on 2014-06-13T20:10:35Z : No. of bitstreams: 1 cruscajunior_e_me_araiq.pdf: 1168682 bytes, checksum: e68054a6af1b3d4f9d9235d07ed0ef75 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho descreve a sintese, a relacao estrutura-funcao, a interacao com membranas e a atividade biologica de um peptideo proveniente da regiao amino-terminal da proteina Esticolisina II (St II). Esta proteina e uma citolisina pertencente a familia das actinoporinas, obtida da anemona marinha Stichodactyla heliantus. Estudos estruturais e biologicos da proteina nativa indicam que a regiao amino-terminal da St II participa do processo de formacao de poros em membranas. Deste modo, visando compreender o comportamento e a importancia dessa regiao para a atividade biologica da St II, 3 analogos contendo os 30 primeiros residuos que compoem a extremidade amino-terminal da St II foram sintetizados e analisados. Os peptideos foram obtidos mediante sintese em fase solida modificando-se um residuo de leucina ou isoleucina por triptofano nas posicoes 2, 7 ou 24. Os estudos conformacionais foram realizados atraves das tecnicas de fluorescencia e dicroismo circular. Para avaliar o comportamento estrutural dos peptideos em solucao, foram realizados estudos de variacao de pH, forca ionica e titulacao com um agente indutor de estrutura, o trifluoroetanol (TFE). Na interacao com mimeticos de membranas, os peptideos foram titulados por tres tipos de detergentes: dodecil-sulfato de sodio (SDS), HPS (N-hexadecil-N,N-dimetil-3-amonio-1-propano-sulfonato) e LPC (1-palmitoil-2-hidroxi-sn-glicero-3- fosfocolina). Complementando o estudo acima, tambem foram realizados experimentos utilizando acrilamida como agente supressor de fluorescencia. Os resultados obtidos demonstram que a estrategia de sintese de peptideos em fase solida atraves do protocolo Fmoc/tBu, utilizada na sintese dos peptideos deste trabalho, foi viavel. O processo de purificacao dos peptideos atraves de HPLC tambem se mostrou eficiente e viabilizou a obtencao do material com alto indice de pureza. / In this study, we describe the synthesis, the relation function-structure, the interaction with membranes and the biological activity of the N-terminus region of the protein Sticholysin II (St II). This protein is a citolisin, which belongs to the family of the actinoporins, purified from the sea anemone Stichodactyla heliantus. According to biological and structural studies of the native protein, the N-terminus region of St II is involved on the pore formation process in membranes. In order to elucidate the function and the importance of this region to the biological activity of St II, three analogs containing the first 30 residues of the N-terminus region of St II were synthesized and analyzed. The peptides were obtained by solid phase synthesis and altered through the substitution of a leucine or isoleucine for a tryptophan on the positions 2, 7 and 24. Circular dichroism (CD) and tryptophan fluorescence studies have been carried out to investigate conformational properties of the peptides. In order to evaluate the structural modification on aqueous solution, studies were performed in order to evaluate the pH, ionic strength and addition of the secondary structural-inducing solvent TFE. The interaction studies with micelles were performed using three different surfactants: sodium dodecil-sulfate (SDS), N-hexadecyl-N,N-dimethyl-3-ammoniumpropanesulfonate (HPS) and lysophosphatidylcholine (LPC), and using acrylamide as a fluorescence suppression agent. We have demonstrated that on solid phase peptides synthesis using the Fmoc/tBu strategy is a success. The purification process of peptides through HPLC, has also revealed to be efficient, once the material was obtained with high purity level above 95%. The experiments of hemolytic activity showed that the three peptides have activities in æM concentration, this results reinforce the idea that the 30 residues of the N-terminus region have an important role on pore formation in membranes.

Made available in DSpace on 2014-10-09T12:49:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:07Z (GMT). No. of bitstreams: 1 10282.pdf: 3788200 bytes, checksum: 89ccf6d2ea9e26c2736dc1bbebcde360 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEn-CNEN/SP