Print, stretch, implant: new material could help build artificial organs

Liheng Cai’s foldable bottlebrush polymers can yield a variety of material structures with different properties that could enable applications from organ transplants to battery technology.

Image credit: Liheng Cai/Softbiomatter Lab/University of Virginia 

The material is the subject of a new article in the journal Advanced Materials, based on work done by the University of Virginia’s Soft Biomatter Laboratory, led by Liheng Cai, an associate professor of materials science and engineering and chemical engineering. The paper’s first author is Baiqiang Huang, a Ph.D. student in the School of Engineering and Applied Science. Their research shows a way to change the properties of polyethylene glycol to make stretchable networks. PEG, as it’s known, is a material already used in many biomedical technologies such as tissue engineering, but the way PEG networks are currently produced — created in water by crosslinking linear PEG polymers, with the water removed afterward — leaves a brittle, crystallized structure that can’t stretch without losing its integrity. 

The breakthrough in elasticity is an important feature, the researchers report, because stretchiness would allow PEG networks’ use in larger structures, or in structures that require some flexibility and movement, such as the scaffolding needed someday for synthetic human organs.

To create this stretchiness, the team built upon existing work from Cai’s lab, which had already developed a way to create very strong synthetic polymers. The approach took a page from the methods used to create stretchy, strong rubber: store length in internal structures at the molecular level. These internal structures, called a “foldable bottlebrush” design, make for a material that can be both very strong and very stretchy. The polymeric molecules have many flexible side chains radiating out from a central backbone that can collapse like an accordion — storing extra length that can be unfolded. “Our group discovered this polymer and used this architecture to show any materials made this way are very stretchable.” Cai said. 

To create the new material, Huang applied the foldable bottlebrush polymer concept to PEG. He exposed the precursor mixture to ultraviolet light for a few seconds, which initiates polymerization to form a bottlebrush-architecture network. This resulted in 3D-printable, highly stretchable PEG-based hydrogels and solvent-free elastomers. “We can change the shape of the UV lights to create so many complicated structures,” Huang said, including structures that are either soft or stiff but remain stretchy by design. This type of versatility in design could one day allow for the creation of new techniques for creating artificial organs or delivery medicines. 

The paper also shows that the stretchy 3D-printable PEG materials are biologically friendly. The researchers cultured cells alongside the materials, to make sure they can live side-by-side, and they were compatible, Huang said. This is good news for its potential use for materials that would go inside the body, such as scaffolding for an organ. 

The paper’s other authors include UVA Engineering colleagues Myoeum Kim, Pu Zhang, Emmanuel Oduro and Daniel A. Rau. The work was funded by the National Science Foundation, National Institutes of Health, UVA LaunchPad for Diabetes and Virginia Innovation Partnership Corporation’s Commonwealth Commercialization fund. 

Source: University of Virginia School of Engineering and Applied Science 

19.11.2025

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