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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento de sistemas micro e nanoestruturados de quitosana/MDI para aplica??es cosm?ticas

Costa Neto, Bento Pereira da 05 March 2009 (has links)
Made available in DSpace on 2014-12-17T15:01:17Z (GMT). No. of bitstreams: 1 BentoPCN.pdf: 1568863 bytes, checksum: bd484a66a36dd1be9ccc75015b40e5e8 (MD5) Previous issue date: 2009-03-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Currently, studies in the area of polymeric microcapsules and nanocapsules and controlled release are considerably advanced. This work aims the study and development of microcapsules and nanocapsules from Chitosan/MDI, using a new technique of interfacial polycondensation combined to spontaneous emulsification, for encapsulation of BZ-3. It was firstly elaborated an experimental design of 23 of the particle in white without the presence of BZ-3 and Miglyol, where the variables were the concentrations of MDI, chitosan and solvent. Starting from the data supplied by the experimental design was chosen the experiment with smaller particle diameter and only added like this BZ-3 and Miglyol. The suspension containing concentrations of 6.25 mg/mL, 12.5 mg/mL, 18.75 mg/mL, 25 mg/mL of BZ-3 were prepared, nevertheless, during the storage time, these formulations presented drug precipitates in the suspensions of 18.75 mg/mL and 25 mg/mL of BZ-3. This apparition of precipitate was attributed to the diffusion of BZ-3 for the aqueous phase without any encapsulation, suggesting so the use of the smaller concentrations of the BZ-3. The suspension containing 6.25mg/mL of BZ3 presented average size of 1.47μm, zeta potential of 61 mV, pH 5.64 and this sample showed an amount of BZ-3 and drug entrapment of 100 %. The suspension containing 12.5mg/mL of BZ-3 presented average size of 1.76μm, zeta potential of 47.4 mV, pH 5.71 and this sample showed an amount of BZ-3 and drug entrapment of 100 %. Then, showing such important characteristics, these two formulations were chosen for futher continuity to the study. These formulations were also characterized by the morphology, FTIR, stability for Turbiscan, DSC and a study of controlled release of the BZ-3 was elaborated in different receiving means / O presente trabalho visou o estudo e desenvolvimento de um sistema micro e nanoestruturado de quitosana reticulada por diisocianato, pela t?cnica de policondensa??o interfacial combinada com emulsifica??o espont?nea, para encapsula??o de benzofenona-3 (BZ-3), um filtro solar qu?mico. Foi elaborado primeiramente um planejamento experimental de 23 para desenvolvimento da formula??o de part?culas de quitosana e MDI (4,4 -difenil metano diisocianato), onde as vari?veis foram ?s concentra??es de MDI, de quitosana e do solvente. A partir dos dados fornecidos pelo planejamento experimental, optou-se pelas condi??es de processo e formula??o capazes de gerar o menor di?metro de part?cula. O estudo prosseguiu com a incorpora??o de BZ-3 e Miglyol (n?cleo das c?psulas formadas). Suspens?es de nanoc?psulas com concentra??es de 6,25 mg/mL, 12,5 mg/mL, 18,75 mg/mL e 25 mg/mL de BZ-3 foram preparadas, por?m durante o per?odo de armazenamento ocorreu o aparecimento de precipitados cristalinos, nas suspens?es de 18,75 mg/mL e 25 mg/mL de BZ-3. Este aparecimento de precipitados cristalinos foi atribu?do ? difus?o da BZ-3 para a fase aquosa n?o ocorrendo sua encapsula??o. A suspens?o contendo 6,25 mg/mL de BZ-3 apresentou di?metro m?dio de 1,47μm, potencial zeta de 61 mV, pH de 5,64 e teor de encapsula??o pr?ximos a 100 %. A suspens?o contendo 12,5mg/mL de BZ-3 apresentou di?metro m?dio de 1,76μm, potencial zeta de 47,4mV, pH 5,71 e teor de encapsula??o pr?ximos a 100 % e foi selecionada juntamente com a de 6,25 mg/mL para a continuidade do estudo. Estas formula??es foram caracterizadas tamb?m pela morfologia, turbidimetria, espectroscopia de absor??o na regi?o do infravermelho, DSC e foi elaborado um estudo de libera??o controlada do f?rmaco em diferentes meios receptores. Em conclus?o, o conjunto dos resultados obtidos demonstra que estas formula??es s?o sistemas promissores para a aplica??o cut?nea de filtros solares

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