Design of dual stimuli-responsive gels with physical and chemical properties that vary in response to light and temperature and cell behavior on their surfaces

Abstract

Cell behaviors are highly sensitive to the surrounding environment. Therefore, in regulating cells, biomaterial substrates should be designed so their properties are similar to the surrounding environments of the cells. For cell regulation, we designed dual stimuli-responsive gels whose physical (elastic modulus) and chemical (hydrophilicity) properties can be changed by varying the UV exposure time and temperature, respectively. A dual stimuli-responsive polymer with photodimerizable groups and temperature-responsive moieties was prepared by copolymerizing 7-methacryloyloxycoumarin (MAC) and methoxyoligoethylene glycol methacrylate (OEGMA). The resulting polymers (P(MAC-co-OEGMA)) had lower critical solution temperatures (LCSTs), which depended on the compositions. A buffer solution containing P(MAC-co-OEGMA) was exposed to ultraviolet light (UV) for gelation, and the elastic modulus increased with increasing exposure time. The cell behavior, including adhesion and spreading, on the surfaces of these gels was investigated. Most of the cells adhered to P(MAC-co-OEGMA) gels with higher elastic moduli, and the cells were spread more effectively at temperatures above the LCST. This was because cell adhesion and spreading were strongly influenced by the physical and chemical properties of the P(MAC-co-OEGMA) gels, which were regulated by varying the UV exposure time and temperature. A buffer solution of dual stimuli-responsive polymer with photodimerizable groups and temperature-responsive moieties undergoes a phase transition from a sol state to a gel state by exposure to ultraviolet light. The resulting gels changed the physical (elastic modulus) and chemical (hydrophilicity) properties by varying UV exposure time and temperature, respectively. Cell adhesion, spreading, and proliferation were strongly influenced by the physical and chemical properties of the polymer gels, which were regulated by varying UV exposure time and temperature.