Being Smarter, Azobenzene-Containing Biomaterial Showing Triple Stimuli-Responsive Phase Change Property to Light, Humidity and Force at Room Temperature.

Multiple stimuli-responsiveness is an attractive property that is studied in physical chemistry and materials chemistry. While, multiple stimuli-responsive phase change in an isothermal way is rarely addressed for functional materials at room temperature. In this study, one azobenzene-containing surfactant AZO is designed for the fabrication of triple stimuli-responsive phase change biomaterial (Alg-AZO) through the electrostatic complexation with natural alginate. Thanks to the photoisomerization ability, molecular flexibility and hydrophilicity of AZO, together with the tailoring effect of alginate on AZO, Alg-AZO could perform reversible isothermal phase transition between liquid crystalline and isotropic liquid states under the stimuli of either light or humidity at room temperature. Furthermore, the humidity-induced isotropic state can also fast transit to ordered state under shear force, owing to the π-π interactions between planar trans-AZO in Alg-AZO material. With good biocompatibility, self-healing property and in vivo wound healing promoting capacity that is promoted by light, humidity and force, Alg-AZO would be suitable for working as a new smart biomaterial in biological and biomedical areas. This work provides a designing strategy for gaining multiple stimuli-responsive smart materials based on biomacromolecules, and also opening a new opportunity for gaining self-healing biomaterials capable of working in various conditions.