Navegando por Palavras-chave "Fibroína De Seda"

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    Hidrogéis e micropartículas de fibroína de seda para liberação modificada de corantes
    (Universidade Federal de São Paulo (UNIFESP), 2020-03-04) Tomoda, Bruno Thorihara [UNIFESP]; Moraes, Mariana Agostini de [UNIFESP]; Universidade Federal de São Paulo
    Natural polymers are biodegradable materials, coming from natural sources and have been studied in the medical-pharmaceutical area. Silk fibroin, obtained from the cocoons of Bombyx mori silkworms, is a promising and versatile protein for application in this area. However, controlled-release systems made of natural polymers, such as silk fibroin, generally exhibit a very rapid release of the compound, reaching equilibrium around 2 hours of release. Thus, the present project proposed the development of a controlled release device through the incorporation of fibroin microparticles containing model dyes in fibroin hydrogels and the study of the release kinetics of the incorporated dyes. The fibroin microparticles were obtained by the atomization method and the incorporation of the model dyes was performed by adsorption. The microparticles were analyzed for their morphology, particle size, efficiency of incorporation of the model dyes and chemical properties. The hydrogels containing the microparticles were characterized in terms of their morphology, chemical, rheological and thermal properties. The release of the compounds was analyzed by UV / Vis spectroscopy, where empirical models were adjusted to the kinetic data. The model dyes showed an efficiency of incorporation in the fibroin microparticles above 70%. The releases of the model dyes of the microparticles were performed in approximately 90 minutes, with Fickian Diffusion being the predominant mechanism in this assay. The releases of the model dyes present in the microparticles incorporated in the fibroin hydrogels persisted for around 900 minutes, with the aid of a Protease XIV for the degradation of the protein, with the Anomalous Mechanism and Case Transport-II being the predominant mechanisms in this assay. Thus, the incorporation of microparticles in fibroin hydrogels proved to be an effective method and allowed to obtain a device capable of increasing the release time of the model dyes into the medium by approximately 10 times. This study opens new possibilities for the development of controlled release systems in several applications, allowing the control of release time.
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    Obtenção de extratos da casca de Barbatimão (Stryphnodendron adstringens) e incorporação em matriz biopolimérica
    (Universidade Federal de São Paulo (UNIFESP), 2020-12-21) Brito, Vivian Pereira De [UNIFESP]; Veggi, Priscilla Carvalho [UNIFESP]; Universidade Federal de São Paulo
    Plants rich in phenolics compounds have become an interesting subject of research due to its potential applications, for instance, as wound healing agents. These bioactive compounds can be incorporated in a natural polymer matrix to be used in biomedical area. In this context, this study aimed to evaluate the extraction of barbatimão and its incorporation in silk fibroin hydrogels. The barbatimão extracts were obtained by two optimized and adapted extraction methods, the first one using an ultrasonic bath with ethanol 65% (v/v) as solvent and the second one using a stirring bath and propylene glycol 50% (v/v) as solvent. The extract obtained by this last method showed the best results related to global yield, antioxidant capacity through FRAP assay and total phenolic content. The reducing sugar content and the antioxidant capacity through ORAC assay did not present significant statistical difference between the methods studied. The presence of tannins was confirmed, in both extracts, by qualitative analyses. The hydrogels with barbatimão extract were compared to hydrogels containing only the ethanol and the propylene glycol solutions. This propylene glycol hydrogel showed the longest gelation time and a reversible sol-gel transition after few days when manipulated and at room temperature. This result could also be confirmed by FTIR analysis with peaks related to silk I structure. The hydrogels containing ethanol and containing the extracts presented conformations of silk I and II, predominating this last one, by the FTIR spectrum. Thermogravimetric analyses by TGA indicated the highest thermal stability of the hydrogels containing propylene glycol. The incorporation of barbatimão extracts did not significantly affect the Hencky stress and strain and deformation values of the hydrogels. However, in the rheology analysis, the hydrogel with barbatimão extract obtained using a stirring bath and propylene glycol 50% (v/v) as solvent showed the highest G’ and G’’ modulus, which means that there was an improvement in the strength and elasticity. This can be explained by the formation of a compact structure that was confirmed by SEM test as well.