Biochemical engineers at Johns Hopkins University used sequences of DNA molecules to cause water-based gels to change shape, demonstrating a new tactic to produce soft robots and "smart" medical devices that don't rely on cumbersome wires, batteries, or tethers.
This is not an unusual occurrence in nature, he added.
"Shape changing is very important in biology," Gracias said. "Think about how a caterpillar turns into butterfly."
To confirm their ability to control which hydrogel targets were activated, team members used DNA sequence-responsive flower-shaped hydrogels. In each "flower," two sets of petals were fabricated, and each set was designed to respond only to one of two different DNA sequences. When exposed to both sequences, all of the petals folded in response. But when they were exposed to just one of the sequences, only the petals matched to that sequence folded.
The team also fabricated hydrogel crab-shaped devices in which the antennae, claws, and legs each curled up in in response to their matching DNA sequence. The crab devices—a shape selected in honor of the popular seafood for which Maryland is known—remained in their actuated state for at least 60 days.
"We've been fascinated by how living cells can use chemical signals to decide how to grow or move and use chemical energy to power themselves," said Rebecca Schulman, the study's other senior author and an assistant professor of chemical and biomolecular engineering. "We wanted to build machines that could act in a similar way. Our fabrication technology makes it possible to design very complicated devices in a range of sizes."
Vicky Nguyen, a Johns Hopkins expert in the mechanics of polymers and biomaterials and an associate professor in the Department of Mechanical Engineering, provided key contributions to the research and was a co-author of the paper.