Unsuspecting sea creature has Earth’s hardest teeth

The planet’s humble mollusks have teeth that mean business. Researchers are now investigating how one of Earth’s hardest and strongest biological materials got so tough, and are looking at a tiny marine mollusk called chitons. Their chompers are harder and stiffer than human tooth enamel and stainless steel, but also wear-resistant and magnetic. 

“Chiton grow new teeth every few days that are superior to materials used in industrial cutting tools, grinding media, dental implants, surgical implants and protective coatings, yet they are made at room temperature and with nanoscale precision,” David Kisailus, a professor of materials science and engineering University of California, Irvine, said in a statement. “We can learn a lot from these biological designs and processes.”

Kisailus is co-author of a study recently published in the journal Science. Using a large species of chiton primarily found in the intertidal zones of the Pacific near the UC Irvine campus. The mollusck’s teeth are primarily made of magnetite nanorods (a magnetic mineral and type of iron oxide) and an organic material found on the United States’ northwest coast and off the coast of Hokkaido, Japan. Kisailus and his colleagues specifically studied how RTMP1—chiton-specific, iron-binding proteins—move into their forming teeth.

The team revealed that the iron-binding proteins in the teeth use small nanoscopic tubules called microvilli to travel from the tissue around immature, nonmineralized teeth into more mature and mineralized teeth. Once they are inside, the proteins bind to scaffolds of chitin nanofibers, the large molecules that dictate how the nanorods that make up the teeth are built. At the same time, the iron from the surrounding tissue also enters the teeth, where it attaches to the RTMP1 protein. This allows the iron oxide that forms the magnetite nanorods to accumulate and eventually grow into the chiton’s signature hard teeth.  

[ Related: This ‘wandering meatloaf’ has teeth made from rare minerals. ]

According to the team, chitons in different regions around the world have the RTMP1 proteins, indicating that “some convergent biological design in controlling iron oxide deposition,” Kisailus explained. Ultimately, the team’s investigation into chiton tooth formation holds important implications for the production of other advanced materials.

“The fact that these organisms form new sets of teeth every few days not only enables us to study the mechanisms of precise, nanoscale mineral formation within the teeth, but also presents us with new opportunities toward the spatially and temporally controlled synthesis of other materials for a broad range of applications, such as batteries, fuel cell catalysts and semiconductors,” he added. “This includes new approaches toward additive manufacturing—3D printing—and synthesis methods that are far more environmentally friendly and sustainable.”

 

More deals, reviews, and buying guides

The PopSci team has tested hundreds of products and spent thousands of hours trying to find the best gear and gadgets you can buy.