A simple hydrogel scaffold with injectability, adhesivity and osteogenic activity for bone regeneration.

Numerous efforts have been made to prepare hydrogels with injectability, adhesivity and osteogenic activity for bone regeneration. However, current hydrogels with these characteristics have limited application in clinical translation due to their complex chemical compositions, which causes difficulty in batch production. In this study, a multifunctional hydrogel with a binary component is prepared for bone regeneration. Dopamine (DA) is first grafted to alginate (Alg) by amidation reaction to give Alg-DA. Then an injectable hydrogel is facilely prepared by mixing strontium ions with the Alg-DA aqueous solution, utilizing the dynamic ionic bonds between the strontium ions and carboxyl groups of Alg-DA. Under the simulated oxidation conditions in vivo, the injectable hydrogel can form stable chemical crosslinkages owing to the presence of catechol groups on Alg-DA. In addition, the catechol groups endow the hydrogel with significant tissue adhesivity. More importantly, the strontium ions endow the hydrogel with osteogenic activity. As indicated by animal experiments, the strontium containing hydrogel scaffolds help to treat rat bone defects within 8 weeks compared to hydrogels without strontium and control groups. This simple hydrogel constructed by using a binary component has achieved several necessary functions, and is expected to be used as a scaffold for bone tissue engineering in clinical applications.