Preparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose

Developing a novel approach for the administration of catechin that ensures sustained bioactivity, even at low doses, is crucial. In this regard, hydrogels were synthesized by polyion complexation of carboxymethyl cellulose (CMC) and chitosan (CS) grafted with epigallocatechin gallate (EGCG-g-CS), which can maintain enduring antioxidant activity. We initially synthesized grafted chitosan with various grafting ratios using a free-radical grafting method. Polyionic complexes were formed by ionic bonding of the amino groups in EGCG-g-CS with the carboxyl groups in CMC. After lyophilization, a hydrogel with a porous structure was obtained. Scanning electron microscopy (SEM), thermogravimetric differential thermal analysis (TG-DTA), and Fourier transform infrared (FT-IR) analyses of the gel structures were conducted. The swelling properties and porosity of the hydrogels were affected by the grafting ratio. The hydrogel gradually released EGCG under low pH conditions owing to chitosan solubilization, resulting in hydrogel disintegration. Additionally, the hydrogels demonstrated cell adhesion and viability. This study suggests that bio-based materials have potential as pH-dependent catechin-releasing materials.Graphical AbstractPreparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose