Rare minerals first discovered in vivo

Part of the Radula of the Crytochiton stelleri, showing hard and strong teeth.Credits: Northwestern University

Rare minerals from rocks found in mollusk teeth

Northwestern University For the first time, researchers have discovered a rare mineral hidden in the teeth of a large mollusk, the chiton, found along a rocky coastline. Prior to this strange surprise, an iron mineral called Santa Barbarite was recorded only in rocks.

This new discovery will help us understand not only the ultra-hard and durable cusp, but also how the entire chiton’s teeth are designed to withstand rock chewing and eating. Researchers have developed bio-inspired inks for 3D printing ultra-hard, hard and durable materials based on the minerals found in chiton teeth.

“This mineral has only been observed in very small amounts in geological specimens and has never been seen in the biological context,” said Derk Joester of Northwestern University, the lead author of the study. I will. “The high water content makes it durable even at low densities. I think this will make your teeth stronger without adding too much weight.

This study is this week Proceedings of the American Academy of Sciences..

Scanning electron microscope image of kitten teeth

Scanning electron microscope image of kitten teeth.

Joester is an associate professor of materials science and engineering at Northwestern University’s McCormick Engineering Department and a member of the Life Process Chemistry Institute. Linus Stegbauer, a former postdoctoral fellow in Joester’s lab, is the first author of this treatise. During his research at Northwestern University, Stegbauer is currently a Principal Investigator at the Institute for Interfacial Process Engineering and Plasma Technology at the University of Stuttgart, Germany.

Single tooth head and upper stylus

Rendering of a virtual section of a single tooth head and upper stylus generated from a 3D reconstruction determined by synchrotron microcomputer tomography.Credits: Northwestern University

One of the hardest known substances in nature, the chiton teeth are attached to a soft, flexible radula-like radula that rubs rocks to collect algae and other food. I will. Joe Star and his team, who have been studying kitten teeth for a long time, have recently focused on the giant reddish-brown kitten, Cryptochiton stelleri.

To examine teeth from Cryptochiton stelleri, Joester’s team worked with Ercan Alp, senior scientist at Advanced Photon Source at Argonne National Laboratory, using the institution’s synchrotron Mössbauer spectroscopy and working with Paul Smeets. I used transmission electron microscopy at Northwestern University Atomic. Nanoscale characterization and experimentation (NUANCE) Center. They found that Santa Barbarite was scattered throughout the upper stylus of the kitten. This is a long, hollow structure that connects the tooth head to the flexible radula.

“The stylus is like the root of a human tooth, connecting the tip of the tooth to the jaw,” says Joester. “This is a tough material that resembles the bones of our body, composed of very small nanoparticles in a fibrous matrix of biopolymers.”

Joester’s group sought to reproduce this material with inks designed for 3D printing. Stegbauer has developed a reactive ink that mixes iron and phosphate ions with a biopolymer derived from chitin. Together with Shay Wallace, a graduate student in the northwestern part of Mark Hersam’s lab, Stegbauer found that mixing ink just before printing worked well.

Radula mouth and protruding front edge

The mouth of the radula and the protruding front end.Credits: Northwestern University

“When nanoparticles are formed in biopolymers, they become stronger and more viscous. This mixture is easy to use for printing. Then, when dried in air, it becomes a hard and hard final material. “Joester says.

“The mechanical structure is as good as its weakest link, so it’s hard to learn how a kitten solves the engineering problem of how to connect its ultra-hard teeth to a soft foundation structure. It’s interesting. “
— — Derk Joester, Materials Scientist

Joester believes that he can continue to learn and develop from materials inspired by kitten needles. This stylus connects the carbide teeth to the soft radula.

“We have been fascinated by kittens for a long time,” he said. “The mechanical structure is as good as its weakest link, so it’s interesting to learn how the kitten solves the engineering problem of how to connect its ultra-hard teeth to a soft foundation structure. Focuses on understanding how this is done in nature for organisms like kittens, as it remains an important issue in modern manufacturing.

Bio-inspired composite 3D printing

Bio-inspired composite 3D printing.Credits: Northwestern University

The study “Persistent Polymorphism of Kiton Teeth: From New Biomaterials to Ink for Additive Manufacturing” was conducted by the National Science Foundation (Awards No. DMR-1508399 and DMR-1905982) and the National Institutes of Health (Awards No. NIH-DE026952). ), Air Force Research Laboratory (Prize No. FA8650-15-2-5518) and Deutsche Forschungsgemeinschaft (Prize No. STE2689 / 1-1). Rare minerals first discovered in vivo

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