Figure 1: Functional materials used in this study.
(A) Photocurable styrenated ST-gelatin, in which styrene groups are derivatized on gelatin molecules, and water-soluble radical initiator (carboxylated camphorquinone). Visible light–induced polymerization of gelatin produces a cross-linked gel.
(B) Thermoresponsive polymer, poly (N-isopropylacrylamide), PNIPAM, and the temperature-dependent phase transition of its aqueous solution. Below 32°C, a transparent homogeneous solution whereas above 32°C, a spontaneously formed gel.