Effect of charge on in vivo adhesion stability of catechol-conjugated polysaccharides

Mussel-inspired adhesive materials have received much attention for biomedical applications primarily because of their underwater/tissue adhesive properties. However, so far, no comparative study focusing on effect of charge differences (i.e., positive vs. negative) in the presence of conjugated catechols has been conducted. In this study, we investigate the physicochemical characteristics and in vitro/in vivo tissue adhesive properties of hydrogels that use anionic (i.e., hyaluronic acid) and cationic (i.e. chitosan) catechol-conjugated polysaccharides. Fe(III) is utilized to effectively prepare both hydrogels. Hyaluronic acid-catechol (HA-C) hydrogels are immediately formed by iron-catechol coordination bonds, while chitosan-catechol (CHI-C) hydrogel is formed by both iron-catechol coordination and catechol-amine covalent reactions. The gelation time and in vitro adhesiveness are similar for both CHI-C and HA-C hydrogels. Differences are found in that the CHI-C hydrogels showed enhanced water-resistance and long-lasting adhesion in vivo. It is noteworthy to mention that the cationic nature of mussel adhesive proteins due to lysine and histidine residues in the pads of Mytilus edulis is known to be an important contributor to underwater adhesion. Thus, this comparative study provides significant insight for the design of effective mussel-inspired adhesive materials.