PPG - Engenharia Química

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Navegando PPG - Engenharia Química por Autor "Brito, Vivian Pereira De [UNIFESP]"

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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.