Fig. 4.

Illustration of the device used to prepare the hydrogel tubes (a). The transparent hydrated CB hydrogel (3%–50%) tubes with good mechanical properties: stand-alone, bending, knotting, and stretching (b). The dehydrated CB hydrogel (3%–50%) tube still retained its transparency and its overall shape and could be bent and stretched without breaking (c). After being rehydrated in water for 24 h, the hydrogel retained its original shape, size and appearance. The outer diameter was 8 ± 0.3 mm, while the inner diameter was 6 ± 0.2 mm with a wall thickness of 1 ± 0.1 mm.