Fabrication of thermoresponsive degradable hydrogel made by radical polymerization of 2-methylene-1,3-dioxepane: Unique thermal coacervation in hydrogel

Abstract Thermoresponsive degradable hydrogels have attracted attention because their properties allow for their use as smart drug carriers for drug delivery systems and cell scaffolds in the living body. In this study, we synthesized thermoresponsive degradable hydrogels via radical copolymerization of 2-methylene-1,3-dioxepane and 2-hydroxyethylacrylate in the presence of a crosslinker at various feed ratios. The synthesized hydrogels showed a temperature-dependent swelling/shrinking behavior, which was also observed in the corresponding linear polymers. During shrinking, coacervate droplets were observed within the hydrogel. Under mild alkaline conditions, the hydrogels were degraded and converted into hydrophilic oligomers. Moreover, cell adhesion to the hydrogel surfaces was observed using poly ( d -lysine)-modified hydrogels. The number of adhered cells increased on the hydrogels that showed shrinking behavior at 37 °C. The prepared hydrogels are expected to be applicable for use in functional cell scaffolding instead of as non-degradation materials.