Toward artificial tissues and organs: New 4D hydrogels bend and curve like natural tissue

A cell-laden 4D hydrogel undergoing a preprogrammed shape transformation
Credit: Courtesy of Aixiang Ding, University of Illinois a...

Researchers are reporting development of new 4D hydrogels—3D materials with the ability to modify their shape over time in reaction to their environment.  The new shape-shifting materials show promise for engineering artificial tissues and organs that can bend and curve more like their natural counterparts.

Existing materials used in tissue engineering typically do not change their overall shape over time, and the capacity to morph might be advantageous for such applications. The novel material reported in the new study is composed of different hydrogel layers that swell or shrink at different rates and extents in response to water or the concentration of calcium. By creating complex layering patterns, researchers can preprogram or guide the material to bend different directions as the layers swell and shrink. This shape-changing mimics natural developmental and healing processes. 

In experiments, the researchers showed that they could form these hydrogels into structures similar to the shape of alveoli, the tiny sac-like structures in the lungs where gas exchange takes place. In addition to their shape-changing ability, the new hydrogels are also highly biocompatible and easy to manufacture, the researchers said. Their study, funded in part by the NHLBI, appeared in the journal Advanced Science.