While it sounds like a tour update for the musician Meat Loaf, this research concerns a large mollusk called a chiton (not a “bat out of hell”). The mollusk, also known as Cryptochiton stelleri, got its nickname because it’s large, reddish-brown and, well, shaped a bit like a meatloaf escaping the pan. It lives along rocky coastlines. The largest chiton in the world, it can reach 13 inches in length.
Researchers were surprised to find santabarbaraite in the mollusk’s tooth because it’s previously been found only in rocks.
Chiton need tough teeth because they essentially chew on rocks to scrape off algae and other food substances. Their teeth are one of the hardest materials in nature and are attached to a flexible tongue-like structure called a radula.
The new research is helping scientists understand how chiton teeth can survive the wear and tear of their dietary needs which could allow them to develop a 3D printer ink that can create ultrahard and durable material.
The study published Monday in the journal Proceedings of the National Academy of Sciences.
Never seen in a ‘biological context’
“This mineral has only been observed in geological specimens in very tiny amounts and has never before been seen in a biological context,” said Derk Joester, senior study author and associate professor of materials science and engineering in Northwestern University’s McCormick School of Engineering, in a statement.
“It has high water content, which makes it strong with low density. We think this might toughen the teeth without adding a lot of weight.”
Using multiple methods of analysis at the Argonne National Laboratory’s Advanced Photon Source and the Northwestern University Atomic and Nanoscale Characterization and Experiment Center, both in Illinois, the researchers found the mineral in the chiton’s upper stylus. In chiton, the stylus connects the tooth to the radula.
“The stylus is like the root of a human tooth, which connects the cusp of our tooth to our jaw,” Joester said. “It’s a tough material composed of extremely small nanoparticles in a fibrous matrix made of biomacromolecules, similar to bones in our body.”
Learning from chiton engineering
Inspired by this material, Joester and his research group wanted to recreate it as ink for 3D printing. The ink includes iron and phosphate mixed into a natural substance produced by chiton. When the ink dries, it creates a stiff material.
“We’ve been fascinated by the chiton for a long time,” Joester said. “Mechanical structures are only as good as their weakest link, so it’s interesting to learn how the chiton solves the engineering problem of how to connect its ultrahard tooth to a soft underlying structure.
“This remains a significant challenge in modern manufacturing, so we look to organisms like the chiton to understand how this is done in nature, which has had a couple hundred million years of lead time to develop.”