Fig. 6. Magnetically driven transformation of 3D thin bioscaffolds enables the generation of hydrogel-based biohybrid actuator with a walking motion.

(A) Scheme illustrates the process of creating 3D thin membrane-based bioscaffolds in a flower shape. Initially, a flat crosslinkable hydrogel precursor is transformed into a 3D morphology and then crosslinked when a magnet is placed above it. After incubation at 37°C, the crosslinked scaffold will be released from the magnet while gelatin dissolves, which simultaneously releases magnetic ink from the scaffold. (B) Scheme illustrating cell seeding and layer formation on the bioscaffolds. (C) Immunostaining of the cardiomyocytes cultured on the surface of the 3D thin bioscaffolds. cTnT (red), DAPI (blue), and F-actin (green). (i and iii) Low magnification. Scale bars, 50 μm. (ii and iv) High magnification. Scale bars, 25 μm. (D) (i) Top view and (ii) side view time-lapse photographs of walking biohybrid actuator (collected for 1 min). Scale bars, 1 cm. (E) Instant velocity of the front foot and rear foot over time. (F) (i) Schematic of the direction of the scaffold contraction, movement, and calcium propagation; (ii) calcium propagation mapping over time for the cardiomyocytes on the center of the scaffold (scale bars: 500 μm); and (iii) analysis of the motion of the scaffold.