Generating complex 3D structures in soft materials

Generating complex 3D structures in soft materials

In plants and animals, soft living tissues routinely adopt complex 3D structures to perform or enhance critical functions. Although such structures have applications in biomedical engineering, robotics, and flexible electronics, most efforts to synthesize them in soft materials diverge fundamentally from biological processes.

Researchers present a technique to direct the polymerization of monomers to form complex 3D architectures from porous hydrogels. Mimicking organic tissue morphogenesis, in which constituents within a single tissue grow at different rates and impose mechanical restraints, the technique modulates oxygen diffusion-inhibited polymerization to enable the formation of engineered heterogeneous, patterned structures. Depending on the patterning, the prefabricated structures self-organize and evolve into a desired configuration.

The strategy effectively utilizes the three essential components dictating living tissue morphogenesis to produce complex 3D architectures: modulation of local chemistry, material transport, and mechanics, which can be engineered by controlling the local distribution of polymerization inhibitor (i.e., oxygen), diffusion of monomers/cross-linkers through the porous structures of cross-linked polymer network, and mechanical constraints, respectively.

They show that oxygen plays a role in hydrogel polymerization which is mechanistically similar to the role of growth factors in tissue growth, and the continued growth of hydrogel enabled by diffusion of monomers/cross-linkers into the porous hydrogel similar to the mechanisms of tissue growth enabled by material transport.

The authors used the technique to generate a variety of biomimetic structures corresponding to plant and animal tissues, including bending in a plant stem and structural changes seen in the respiratory airways of asthma patients.

The findings offer an approach to study and replicate complex soft tissue architectures, according to the authors.