Reticulação física do hidrogel de amido por ciclos curtos de resfriamento e aquecimento na presença de glicerol para potencial uso como curativo dérmico

Abstract

In this work, the development of films from starch hydrogel physically cross-linked in the presence of glycerol, via short cooling and heating cycles, was studied. Furthermore, in view of a possible application of this material as a dermal dressing, it is also proposed the incorporation of pracaxi oil in different concentrations to improve its activity as a dermal dressing, since this oil contains a high concentration of oleic and behenic acid, the which respectively confer healing properties as well as restore skin hydration and permeability. The study proposes the use of short cooling and heating cycles to favor physical crosslinking into polymer matrix, which is based on the physical crosslinking method via freeze-thaw. These cycles were chosen, considering that the processes commonly adopted to promote physical crosslinking through the freezing-thawing of gels require extensive time for their completion. The different films containing starch and glycerol, developed and submitted to different short cycles of cooling and heating, were characterized in terms of their visual appearance, morphology, structure, thermal and mechanical properties, evaluation of swelling and solubility in physiological pH and vapor permeability of water. Regarding the results, they showed that the presence of glycerol at a concentration of 30% already promoted the physical crosslinking of the starch hydrogel, which was intensified by the short cooling and heating cycles, since an increase in the density of the starches films (AG-R1, AG-R2 and AG-R4) were observed. The films obtained also showed favorable physicochemical characteristics for use as dressings in reparative processes, such as easy handling, flexibility, high swelling capacity, permeability to water vapor and low solubility rate. However, analyzing the test data, it was found that the AGR2 film showed considerable modification, since it indicated an increase in density and a reduction in thickness, thus showing that the morphology formed is different from other films, suggesting an entanglement that does not allow the incorporation of molecules of the solvent (water) used in the test. Thus, pracaxi oil was incorporated into this film at different concentrations and these were characterized in terms of their visual appearance, morphology, structure, mechanical properties, evaluation of swelling and solubility at physiological pH and permeability to water vapor. In general, the data obtained indicated that variations in the concentration of pracaxi oil did not significantly vary the results of the analyses, which suggests that both films (AG-R2-OP2, AG-R2-OP4 and AG- R2-OP6) are promising in the development of dressings for wound protection, which makes it necessary to develop future studies to choose which oil concentration offers the greatest benefits to the film and confirm these characteristics.