Researchers discovered a rare type of iron in a living organism for the first time

Shane McGlaun - Jun 3, 2021, 7:13am CDT
Researchers discovered a rare type of iron in a living organism for the first time

Researchers at Northwestern University have discovered a rare mineral hidden inside the teeth of a chiton. A chiton is a large mollusk found along rocky coastlines. The rare mineral is called santabarbarait, and before being found inside the teeth of the mollusk, it had only been documented in rocks. The discovery of the mineral in the creature’s teeth helps researchers understand how the entire chiton tooth, not just the extremely hard and durable cusp, is designed to survive chewing on rocks as it feeds.

The researchers created a bio-inspired ink for 3D printing ultra-hard, stiff, and durable materials based on minerals found in the teeth. Prior to discovering the mineral inside the teeth of the mollusk, it had only been observed in geological specimens in very small amounts. The discovery marks the first time it’s been seen in a biological context.

The mineral has high water content making it strong with low density, and the researchers believe it toughens the teeth without adding additional weight. Chiton teeth are one of the hardest known materials in nature and are attached to a soft, flexible, tongue-like radula that scrapes over rocks to collect algae and other food.

Researchers on the study investigated the Cryptochiton stelleri, a giant, reddish-brown chiton known as the “wandering meatloaf.” During the study, the team discovered santabarbarait dispersed throughout the upper stylus of the chiton, which is a long, hollow structure that connects the head of the tooth to the flexible radula membrane. The stylus is sort of like the root of the human tooth.

After the study, the team developed a reactive ink comprised of iron and phosphate ions mixed with the biopolymer derived from the chitin. The team says the ink prints well when mixed immediately before printing. As nanoparticles form in the biopolymer, it gets stronger and more viscous. Subsequent air drying leads to the hard and stiff final material.


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