Stimuli-Responsive Injectable In situ-Forming Hydrogels for Regenerative Medicines

Research on injectable in situ-forming hydrogels has been conducted in diverse biomedical applications for a long period. These hydrogels exhibit sol-to-gel phase transition in accordance with the external stimuli such as temperature change. Also, unlike the traditional surgical procedures the hydrogels have the distinct properties of easy management and minimal invasiveness via simple aqueous state injections at target sites. Currently, numerous polymer materials have been reported as potential stimulus-induced in situ-forming hydrogels. In this review, a comprehensive overview of the state-of-the-art of these rapidly developing materials has been outlined. In situ-forming hydrogels formed by electrostatic and hydrophobic interactions as well as their mechanistic characteristics and biomedical applications in regenerative medicine have also been discussed. The review concludes with perspectives on the future of stimulus-induced in situ-forming hydrogels.