Síntese e caracterização de hidrogéis a partir de alginato e mucilagem de ora-pro-nobis (Pereskia aculeata Miller)

Abstract

Hydrogels are three-dimensional cross-linked polymeric networks capable of absorbing large amounts of water or biological fluids and can be produced from synthetic, natural polymers or blends of different materials. Oro-pro-nobis mucilage (MOPN) is a polysaccharide composed of protein-associated arabinogalactan biopolymer, has high hygroscopicity and the ability to form viscous solutions that reveals its potential for hydrogel synthesis. The objective of the present work was to synthesize and characterize hydrogels constituted with different alginate and MOPN concentrations. The hydrogels were produced by ionic gelation employing CaCl2 (1,5 and 3,0% w / v) and solutions containing 0,5, 0,75, 1,0, 1,25% (w/v) sodium alginate, and 0,25, 0,5, 0,75, 1,0 and 1.25% (w/v) MOPN. A control treatment with 1,5% (w/v) of alginate was also produced, which along with the others, was characterized as to the rheological behavior of the solution, compressibility, swelling degree, morphological analysis, infrared spectroscopy with transform Fourier (FTIR), X-ray diffraction (XRD), differential exploratory calorimetry (DSC) and thermogravimetry (TGA). Polymeric solutions containing higher MOPN content showed higher apparent viscosity and pseudoplastic behavior, while alginate rich solutions over MOPN were classified as Newtonian fluids. The results indicated that higher alginate and lower MOPN concentrations produce hydrogels that support higher compressive stress, with a more cross-linked and less amorphous structure, presenting a lower degree of swelling. The high MOPN hydrogels revealed a more amorphous and less rigid structure, with many small pores and lumps deposition that contributed to a high degree of swelling. The thermal analysis, in turn, indicated that the treatment synthesized with alginate alone was more thermally stable than the others. The dissolution of hydrogels in simulated intestinal environment made their application in a controlled release system unfeasible. However, the maximum stress values supported by this material are within the range stipulated in the literature for tissue engineering applications, revealing the potential application of these hydrogels in the synthesis of single tissues.In addition, as properties described for alginate hydrogen and MOPN, which can also be used to encapsulate food additives such as dyes, to protect bioactive compounds and finally, to immobilize enzymes used in the treatment of juices, teas and wines.