Temperature Dependent Reversible Self Assembly of Methacrylated Collagen Gels

Hydrogel-based tissue engineering scaffolds can allow tissues to repair and regenerate by providing a 3D environment similar to soft tissue. Type I collagen has the ability to assemble into a fibrillar gel at physiological temperature and pH, while promoting cell adhesion and growth. Our lab has modified type I collagen by covalently adding methacrylate groups to lysine residues to create collagen methacrylamide (CMA). This biomaterial, like collagen, maintains the ability to self-assemble, and can then be photocrosslinked with long-wave UV light and a water-soluble photoinitiator, which allows extensive spatiotemporal control of mechanical and biochemical properties [1]. In characterizing CMA and developing it for other applications, we discovered an interesting property. Unlike type I collagen hydrogels, which maintain a stable fibrillar network during cooling and freezing, CMA will spontaneously disassemble at temperatures less than 10°C. In this paper, we discuss the temperature-dependent rheological properties of CMA as well as the nature of its molecular and supramolecular structure in comparison to collagen.