A rare mineral inside the teeth of a chiton, a large mollusk found along rocky coastlines, led to a bioinspired ink for 3D printing and also may one day be used in the emerging field of soft robotics, according to researchers who made the discovery while working at the U.S. Department of Energy’s (DOE) Argonne National Laboratory.
Using Argonne’s Advanced Photon Source (APS), a DOE Office of Science User Facility, a research team from Northwestern University discovered an iron mineral, called santabarbaraite, which previously was only documented in rocks. The finding helped researchers understand how the whole chiton tooth — not just the ultrahard, durable cusp — is designed to endure grazing on rocks to feed.
“Having access for these experiments was incredibly invaluable. And there was no other location that offered what we needed.” — Derk Joester, associate professor of materials science and engineering at Northwestern University
The rare mineral was discovered with the use of the APS, which produces ultrabright X-rays that can penetrate thick samples of material. Two different X-ray methods provided a detailed and accurate determination of the mineral’s properties. It was exactly what the team required to make the discovery, said Northwestern’s Derk Joester, one of the researchers and an associate professor of materials science and engineering in Northwestern’s McCormick School of Engineering.
“Having access for these experiments was incredibly invaluable,” said Joester of working at APS. “And there was no other location that offered what we needed.”
Santabarbaraite was only previously observed in geological specimens in very tiny amounts and was never seen in a biological context. It has high water content, which makes it strong with low density. The discovery led to using this mineral to create an ink that can be used for 3D printing of durable materials. The ink is for composites that have hardness and stiffness in the range of such materials as concrete, brick, glass, carbon fiber reinforced plastics or stainless steel. In the future, it could be used in the emerging soft robotics field, which includes new technologies ranging from space devices for NASA to prosthetics for humans.
“Just use your imagination,” Joester said.
The research team’s findings were published in the Proceedings of the National Academy of Sciences of the United States of America.
The group used many different X-ray methods at the APS, and they all pointed to this same unusual mineral, said Matt Newville, a University of Chicago research associate professor and beamline scientist at the university’s Geo Soil Enviro Consortium for Advanced Radiation Sources (GSECARS). He was also acknowledged for his work in the article.
“Another amazing part of this work is that at the APS we have all of these very sophisticated instruments that are the result of decades or even centuries of steady scientific innovation,” said Newville. “As we use the latest technological achievements, we continue to discover new and amazing things in nature. Whether that’s the molecular structure of the spike protein in SARS coronavirus or that these ancient mollusks can synthesize these very hard materials, we’re still learning chemistry and material science.”
Esen Ercan Alp, a senior physicist at Argonne’s X-ray Science Division and a co-author on the paper, pointed to the APS’s Mossbauer imaging capability, which can give precise information about the chemical, structural, magnetic and time-dependent properties of a material.
“These techniques are available in three other locations around the world, but none of them put it together with a microscope like at the APS,” said Alp.
Joester’s team collaborated with Alp to use the APS, and worked with Paul Smeets, a postdoc working with Joester, to use transmission electron microscopy at Northwestern’s Atomic and Nanoscale Characterization and Experiment (NUANCE) Center.
They found santabarbaraite dispersed throughout the chiton’s upper stylus, a long, hollow structure that connects the head of the tooth to the flexible radula membrane. The stylus is like the root of a human tooth, which connects the cusp of our tooth to our jaw. It’s a tough composite material composed of extremely small nanoparticles in a fibrous matrix made of biomacromolecules, like bones in the human body, according to Northwestern.
Linus Stegbauer of Northwestern, the first author of the study, challenged himself to recreate this material but at a larger scale. To this end, he designed an ink for 3D printing. Stegbauer developed a reactive ink comprising iron and phosphate ions mixed into a biopolymer derived from the chitin. The Northwestern team found that the ink printed well when mixed immediately before printing.
A version of this story was originally published by Northwestern University.
About the Advanced Photon Source
The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.
This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.