A rubbery material made using a three-dimensional printer can transmit electrical signals and mechanically fold like biological tissue in predictable ways. The work, published in this week’s issue of Science by researchers at the University of Oxford, UK, could pave the way for tissue engineering, controlled drug release technologies or other medical applications.
“We can mimic tissue properties using relatively easily obtained building blocks,” says chemical biologist Hagan Bayley, who led the work. “It’s at a primitive level at the moment, but it’s an interesting attempt to make things that behave like tissue by bottom-up fabrication.”
The technique involves printing tiny water droplets into specific positions in an oil bath. The droplets acquire a lipid monolayer and form bilayers with other droplets in the growing network. Some of these droplets also contain membrane proteins to allow for long-range electrical communication, like in a nerve axon; some have different concentrations of salt to create a gradient for osmosis-driven folding.
In the video above, two colored dyes are included to visualize the printing process. In the paper, the authors demonstrated that they could send an electrical signal along a defined path, and fold a flower-shaped network of droplets into a hollow sphere.
“They’ve demonstrated some engineered functionality to what they’ve printed,” says Lawrence Bonassar, a biomedical engineer at Cornell University in Ithaca, New York, who was not involved in the study. “This opens the door to printing neuronal structures or guiding neuronal in-growth in a very targeted way. That, in some ways, is a bit of a holy grail.”