Studies on the physicochemical properties, gelling behavior and drug release performance of agar/κ-carrageenan mixed hydrogels

A series of agar/kappa-carrageenan mixed hydrogels with different mass ratios were prepared, and their physicochemical properties, gelling behavior and drug release performance were determined and analyzed. The results showed that the gel strength, the gelling temperature and the gel melting temperature decreased with the increase of kappa-carrageenan, while the apparent viscosities increased. Optical rotation and differential scanning calorimetry (DSC) indicated that there did exist intermolecular interactions between agar and kappa-carrageenan, and the detailed gelling mechanism of the mixed hydrogels was proposed, which was different from that of the previous research. Besides, agar/kappa-carrageenan mixed hydrogels were used as carriers for the delivery of metformin hydrochloride (MET). The results showed that the drug loading efficiency and the sustained release capacity of agar hydrogels could be enhanced by the addition of kappa-carrageenan, and the release profile was mainly dominated by the electrostatic interaction between the MET and the polysaccharides. These results indicated that kappa-carrageenan had the potential to improve the physicochemical properties and drug release performance of agar hydrogel. (C) 2020 Elsevier B.V. All rights reserved.