Effect of ethanol treatment on physical property of photopolymerized hyaluronic acid/silk fibroin hybrid hydrogel

Hyaluronic acid (HA) is highly biocompatible and is therefore utilized in various medical fields. Recent efforts have achieved a wide variety of HA-based hydrogel fabrications and their potent applications in tissue engineering. Nevertheless, HA hydrogels have limitations in physical property control due to the nature of HA. In this study, a hybrid hydrogel was formed with hyaluronic acid-methacrylate (HAMA) and silk fibroin-methacrylate (SFMA) via photopolymerization, followed by physical cross-linking of silk fibroin (SF) chains. The photopolymerization was completed within 5 min under UV irradiation, although the gel point increased with an increase in SFMA content. By ethanol treatment, the SF domain formed beta-sheet structures, resulting in double network in HA/SF hybrid hydrogel. As a result, the shear modulus of the HA/SF hybrid hydrogel significantly increased with an increase of SFMA content, while the swelling ratio decreased. In addition, the HA/SF hybrid hydrogel exhibited gel-sol transition under shear stress, suggesting potential application as an injectable material.