Hidrogel de quitosana/colágeno para a liberação do óleo essencial de alecrim pimenta (Lippia sidoides Cham)

Abstract

Hydrogels are cross-linked polymeric networks, natural or synthetic, that possess a high capacity for swelling in aqueous media. Natural biopolymers, such as chitosan, which is biodegradable, biocompatible, and has healing properties, and collagen, which provides mechanical resistance and hydrophilicity, are used in the synthesis of hydrogels. The combination of these polymers not only enhances cell proliferation for tissue repair but is also crucial for the controlled release of bioactive compounds, such as those present in essential oils. The essential oil of Lippia sidoides Cham. (LS), popularly known as rosemary pepper, has antimicrobial and antileishmanial activity due to its major constituent, thymol. The objective of this research was to synthesize and characterize chitosan and collagen hydrogels with LS, using a simple synthesis method in which chitosan was solubilized in 1% acetic acid, then collagen and Tween were added along with LS. Three hydrogels were synthesized: one containing only chitosan and collagen (at a concentration of 3% chitosan and 3% collagen), named HQC, and two others with the same amounts of polymers but containing LS, one at 0.5% and the other at 1% LS, named HQCL0.5 and HQCL1, respectively. Differential Scanning Calorimetry (DSC) thermal analysis results showed that the hydrogels loaded with LS exhibited changes in the intensity of thermal peaks, suggesting a possible stabilizing effect of the oil on the polymeric matrix. Furthermore, the HQCL0.5 and HQCL1 hydrogels showed an oil loading capacity (CC%) of 2.68% and 3.02%, respectively. In the in vitro release assay, HQCL0.5 demonstrated a more controlled release profile due to a lower predominance of peaks compared to HQCL1. However, hydrogels containing LS showed moderate toxicity in Artemia salina, which makes it necessary to advance studies in order to reduce this toxicity, allowing its future use as a carrier for this essential oil.