"Smart" Stimuli-responsive Injectable Gels for Bone Tissue Engineering Application

Bone grafting, as the current gold-standard for large scaled bone damage of various causes, has faced challenges from both the source and appliance. Emerging new tissue engineering substitutes are demonstrating more options and possibilities, with their improved biocompatibility, accessibility, and customizable function. Amongst them, injectable gels (IGs) are a class of gel material displaying astonishing non-invasive properties and surgical viability. While possessing responsiveness toward specific stimuli, they change their physical form in vivo, thus serving as wonderful biomaterials and drug delivery systems. In this review, the mechanics of stimuli-responsive IGs developed during the past decade are illustrated. Two branches of crosslinked gels - co-valent and non-covalent crosslinked IGs and their composition and customization are introduced. In conclusion, the present trend in bone tissue engineering research is summarized and made an outlook for future. It is hoped that this comprehensive review can provide a proper reference for the development of new IGs.