Scientists have developed a 3D printer that has been specially adapted to build therapeutic biomaterials from multiple materials.
This, the researchers say, could be a step toward on-demand printing of complex artificial tissues for use in transplants and other surgeries.
"Tissues are wonderfully complex structures, so to engineer artificial versions of them that function properly, we have to recreate their complexity," said the study's lead author, Ali Khademhosseini, who is also the professor of engineering at the UCLA Samueli School of Engineering.
"Our new approach offers a way to build complex biocompatible structures made from different materials."
Published in the Advanced Materials journal, the study explains how the new technique uses a light-based process called stereolithography, and it takes advantage of a customised 3D printer designed by Khademhosseini himself that has two key components.
The first of which is a custom-built microfluidic chip, that is, a small, flat platform similar in size to a computer chip. This is used alongside multiple inlets that each "prints" a different material. The other component is a digital micromirror, an array of more than a million tiny mirrors that each moves independently.
The researchers explained how they used different types of hydrogels in the breakthrough. These are materials that, after passing through the printer, form scaffolds for tissue to grow into.
"The micromirrors direct light onto the printing surface, and the illuminated areas indicate the outline of the 3D object that's being printed," the scientists explained.
"The light also triggers molecular bonds to form in the materials, which causes the gels to firm into solid material. As the 3D object is printed, the mirror array changes the light pattern to indicate the shape of each new layer."
When testing out the process, the researchers first made simple shapes, such as pyramids. Then, they made complex 3D structures that mirror parts of muscle tissue and muscle-skeleton connective tissues, proving how it could work to replace real tissue.
The next step was to prove that the prototype prints work in a living organism. They implanted them in rats to find that they weren't rejected. The study didn't state whether they have been implanted in humans, yet, but that is no doubt the scientists' next plan of action.
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