Collagen-based shape-memory biocomposites

Shape-memory hydrogels (SMHs) have been used for various biomedical applications, such as injectable scaffolds in noninvasive procedures and as carriers for drugs and stem cells. However, most SMH studies have investigated properties related to shape recovery rather than bioactivities governed by hydrogel micro/nanostructure. In this study, one of the main structural proteins in tissues and organs, collagen, was incorporated into SMHs, and by varying the fabrication procedure, two different collagen-based SMHs were obtained. The first was a collagen Cryo-gel that could immediately recover its programmed shape. The second was a fibrous collagen gel (F-gel) fabricated by collagen fibrillation that required more time for recovery but possessed a much higher shape fixity ratio and better supported cell adhesion and growth in vitro. To combine the advantages of the two hydrogels, we fabricated a new collagen-based biocomposite that incorporated fibrillated collagen and photo-crosslinkable methacrylated collagen (Col-ma). A collagen/Col-ma ratio of 5:5 was the most favorable for shape recovery and cellular activity.