Fabrication of Polypyrrole-Grafted Gelatin-Based Hydrogel with Conductive, Self-Healing, and Injectable Properties

The self-healing hydrogel and conductive hydrogel have attracted extensive attention in tissue engineering. The self-healing hydrogel can restore its original structure and functionality after damage. The conductive hydrogel is beneficial to the differentiation and proliferation of electrical-stimuli-responsive cells. It is significant to integrate the self-healing ability and the electrical conductivity into a single hydrogel system. Herein we present polypyrrole-grafted gelatin-based hydrogels with combined conductive, self-healing and injectable properties. Methacrylic anhydride was first grafted onto gelatin to form double-bond-functionalized gelatin. Then, the commonly used conductive polymer polypyrrole was grafted onto gelatin by reacting with the double bond. Finally, the polypyrrole-grafted gelatin was mixed with ferric ions to construct the hydrogels. As revealed by the results, the hydrogels possess good conductivity owing to the incorporated polypyrrole and ferric ions. The reversible ionic interactions of ferric ions with gelatin and polypyrrole endow the hydrogels with self-healing abilities. It is interesting that the hydrogels exhibit good injectable properties attributed to their self-healing abilities. Moreover, the hydrogels show a controllable porous structure, an inhibited swelling ability, and good cytocompatibility and blood compatibility.