Nanorods Enable Regeneration of Damaged or Severed Materials

Researchers model how nanorods in a polymer can mimic the ability of amphibians to grow back lost limbs

2 min read
Nanorods Enable Regeneration of Damaged or Severed Materials

Sometimes when you combine nanotechnology with biomimetic capabilities you get the somewhat mundane, such as the water-repellant properties of a lotus flower. But other times, you get superhero capabilities, like being able to climb a wall like Spiderman.

Now we have a biomimetic capability enabled by nanotechnology that seems to be really something out of sci-fi—regenerating damaged or severed sections of material, just as some amphibians can grow back amputated limbs.

Although the technology has only been demonstrated in a computer model, it marks the first time that bulk sections of severed materials have been shown to be capable of regenerating.

"This is one of the holy grails of materials science," said Dr. Anna C. Balazs, professor of Chemical and Petroleum Engineering at the University of Pittsburgh, in a press release. "While others have developed materials that can mend small defects, there is no published research regarding systems that can regenerate bulk sections of a severed material. This has a tremendous impact on sustainability because you could potentially extend the lifetime of a material by giving it the ability to regrow when damaged."

Balazs, who is the principal author of a recently published paper about the simulation in Nano Letters (“Harnessing Interfacially-Active Nanorods to Regenerate Severed Polymer Gels”),  wanted to find a way for a material to sense that damage had occurred, to then initiate growth to build back, and then stop the growth at the correct point.

“Our biggest challenge was to address the transport issue within a synthetic material,” Dr. Balazs said. “Biological organisms have circulatory systems to achieve mass transport of materials like blood cells, nutrients and genetic material. Synthetic materials don’t inherently possess such a system, so we needed something that acted like a sensor to initiate and control the process.”

To do that, Balazs and her colleagues developed a sensor based on nanorods.

In the computer models, the research team developed a hybrid material consisting of nanorods about 10 nm thick that had been embedded in a polymer gel, which itself is surrounded by a solution containing monomers and chemical crosslinkers. The monomers can combine with other molecules to form a polymer and the crosslinkers join one polymer chain to another. This setup mimics the biological process known as a “dynamic cascade”, which occurs when amphibians regenerate tissue.

When some force severs the material, the nanorods near the cut act as sensors and migrate to the new edge of the material. The nanorods both anchor themselves at the new edge of the material and initiate a polymerization reaction between the monomers and the crosslinkers. The end result should be that the replacement material grows to be just like the material that was lost.

In future work, the team is looking at ways to make the bond between the old material and the new material stronger. And again, they are looking at nature, specifically the root system of giant sequoia trees.

Balazs adds: “One sequoia tree will have a shallow root system, but when they grow in numbers, the root systems intertwine to provide support and contribute to their tremendous growth. Similarly, the skirts on the nanorods can provide additional strength to the regenerated material.”

Image: University of Pittsburgh

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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