Obtenção e caracterização de nanopartículas de quitosana e carboximetil-β-ciclodextrina contendo resveratrol

Abstract

Chitosan (CS) and carboxymethyl-β-cyclodextrin (CM-β-CD) nanoparticles were obtained spontaneously by the attraction between molecules of opposite charge. CS is a biodegradable cationic polyelectrolyte capable of interacting and forming polyelectrolytic complexes with CM-β-CD, modified anionic cyclodextrin. Resveratrol (RES), a polyphenol with excellent pharmaceutical properties, was incorporated into this system and characterized. The parameter that changed in this study was the ratio (r) between the carboxylate groups of CM-β-CD and the amino groups of CS, with molar ratio between 0.23 and 0.45. CM-β-CD was synthesized from β-CD and characterized by XRD, FTIR and TG / DTG that confirmed the successful chemical modification. The obtained CM-β-CD had a degree of substitution of  5, with a molar mass of 1446 g/mol by Maldi TOF. Through the physical-chemical characterization it was possible to verify the formation of nanoparticles of CS/CM-β-CD, which had a spherical shape and particle size ranging from 100 to 400 nm, while with the RES the diameter was around 160 nm. Regarding thermal analysis, it was observed that the increase in temperature did not favor the maintenance of the complexes between CS/CM-β-CD and CS/CM-β-CD with RES. The ITC study was carried out to assess physical-chemical parameters of intermolecular interactions, between CS, CDs (β-CD and CM-β-CD) and RES. Regarding the affinity between RES and the cyclodextrins, a greater complexing capacity was observed between RES and the anionic CD, suggesting that the complexes formed are more stable, with a 2:1 stoichiometry (CD / RES).