Made available in DSpace on 2014-12-17T15:41:55Z (GMT). No. of bitstreams: 1 IdyllaST_DISSERT.pdf: 1649846 bytes, checksum: b16782ef605bdc7a1d3225b281a6f2b3 (MD5) Previous issue date: 2011-11-08 / Chitosan nanoparticles have been used in several systems for the controlled release of drugs. The aim of this study was to obtain and characterize chitosan nanoparticles prepared by the method of coacervation / precipitation using sodium sulfate at different concentrations as the crosslinking agent. The characterization was done using zeta potential and small angle Xray scattering, SAXS. The dispersions of chitosan were obtained at pH 1 and pH = 3. The results of zeta potential at pH = 1 ranged from +64.8 to +29.27 mV and for pH = 3 they varied from +72.4 to +23.48 mV, indicating that the chain of chitosan is positively charged in acidic pH and the behavior of nanoparticles in terms of surface charge was independent of pH. However, the results indicated a dependence of particle size in relation to pH. This difference in behavior was explained by the influence of enthalpic and entropic components / Nanopart?culas de quitosana t?m sido utilizadas em v?rios sistemas destinados a libera??o controlada de f?rmacos. O objetivo desse trabalho foi a obten??o e caracteriza??o de nanopart?culas de quitosana atrav?s do m?todo de coacerva??o/precipita??o utilizando o sulfato de s?dio em diferentes concentra??es como agente reticulante. A caracteriza??o foi feita utilizando potencial zeta e espalhamento de pequenos ?ngulos, SAXS. As dispers?es de quitosana foram obtidas a pH=1 e pH=3. Os resultados do potencial zeta variaram no pH = 1 de +64,8 a +29,27 mV e no pH = 3 de +72,4 a +23,48 mV, indicando que a cadeia de quitosana fica carregada positivamente em pH ?cido e que comportamento das nanopart?culas em termos de carga superficial foi independente do pH. Entretanto, os resultados indicaram depend?ncia do tamanho de part?cula em rela??o ao pH. Essa diferen?a em termos de comportamento foi explicada pela influ?ncia dos componentes ent?lpicos e entr?picos

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-06-21T19:57:35Z No. of bitstreams: 1 FatimaDuarteFreire_TESE.pdf: 3248766 bytes, checksum: 8e2bf08690970bd4823d71ff58b8c29f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-23T17:44:50Z (GMT) No. of bitstreams: 1 FatimaDuarteFreire_TESE.pdf: 3248766 bytes, checksum: 8e2bf08690970bd4823d71ff58b8c29f (MD5) / Made available in DSpace on 2016-06-23T17:44:50Z (GMT). No. of bitstreams: 1 FatimaDuarteFreire_TESE.pdf: 3248766 bytes, checksum: 8e2bf08690970bd4823d71ff58b8c29f (MD5) Previous issue date: 2015-03-30 / A infec??o causada pelo Helicobacter pylori tem sido associado a v?rias doen?as g?stricas, inclusive o c?ncer g?strico. Esta bact?ria coloniza a mucosa g?strica de metade da popula??o do mundo, e os tratamentos dispon?veis s?o mal sucedidos em praticamente um em cada cinco pacientes. Pol?meros mucoadesivos, tais como quitosana, s?o usados como sistemas de libera??o g?stricos para uma melhor libera??o do f?rmaco nos locais de atua??o. Neste trabalho, part?culas de quitosana contendo amoxicilina foram obtidas pelo m?todo de coacerva??o/precipita??o visando uma libera??o controlada do f?rmaco no ambiente do est?mago, no intuito de melhorar a efic?cia terap?utica da amoxicilina no tratamento do Helicobacter pylori. A incorpora??o da amoxicilina foi feita utilizando duas t?cnicas diferentes: durante a forma??o das part?culas e por adsor??o das part?culas formadas .As part?culas foram caracterizadas quanto ao tamanho m?dio, potencial zeta, DSC, FTIR, efici?ncia de encapsula??o e libera??o in vitro em HCl 0,1N. As part?culas apresentaram uma efici?ncia de encapsula??o de 83%, tamanho m?dio de part?cula nanom?trica e potencial zeta positivo (20 mV). A amoxicilina encapsulada nas micropart?culas teve libera??o in vitro de apenas 40 % em 120 minutos. / The infection caused by Helicobacter pylori (H. pylori) is associated with gastroduodenal inflammation can lead to the development of gastritis, gastric or duodenal ulcer and gastric cancer (type 1 carcinogen for stomach cancer). Amoxicillin is used as first-line therapy in the treatment of H. pylori associated to metronidazole or clarithromycin, and a proton pump inhibitor. However, the scheme is not fully effective due to inadequate accumulation of antibiotics in gastric tissue, inadequate efficacy of ecological niche of H. pylori, and other factors. In this context, this study aimed to obtaining and characterization of particulate systems gastrorretentivos chitosan - amoxicillin aiming its use for treatment of H. pylori infections. The particles were obtained by the coacervation method / precipitation using sodium sulfate as precipitating agent and crosslinking and two techniques: addition of amoxicillin during preparation in a single step and the sorption particles prior to amoxycillin prepared by coacervation / precipitation and spray drying. The physicochemical characterization of the particles was performed by SEM, FTIR, DSC, TG and XRD. The in vitro release profile of amoxycillin free and incorporated in the particles was obtained in 0.1 N HCl (pH = 1.2). The particles have higher encapsulation efficiency to 80% spherical shape with interconnected particles or adhered to each other, the nanometric diameter to the systems obtained by coacervation / precipitation and fine for the particles obtained by spray drying. The characterization by FTIR, DSC and XRD showed that the drug was incorporated into the nanoparticles dispersed in the polymeric matrix. Thermal analysis (TG and DSC) indicated that encapsulation provides greater heat stability to the drug. Amoxicillin encapsulated in nanoparticles had slower release compared to free drug. The particles showed release profile with a faster initial stage (burst effect) reaching a maximum at 30 minutes 35% of amoxicillin for the system in 1: 1 ratio relative to the polymer and 80% for the system in the ratio 2: 1. Although simple and provide high encapsulation efficiency of amoxicillin, the process of coacervation, precipitation in one step using sodium sulfate as precipitant / cross-linker must be optimized in order to adjust the release kinetics according to the intended application.