Scientists have recorded how mother-of-pearl assembles itself into an ideal structure

Molluscs build shells to protect their soft tissues from predators. Mother of pearl that is marine

organisms use for "construction", hascomplex and very correct structure. This makes it an incredibly durable material. Depending on the species, mother-of-pearl can reach tens of centimeters in length. Regardless of size, each mother-of-pearl is composed of materials deposited in many separate cells in several different places at the same time. How exactly this highly periodic and homogeneous structure arises from the initial disorder has not been known until now.

Researchers from Zlotnikov's groupIn collaboration with the European Synchrotron Radiation Laboratory (ESRF) in Grenoble, the internal structure of early and mature mother-of-pearl was examined in great detail. Using synchrotron-based holographic X-ray nanotomography, they were able to record the growth of nacre over time. “Mother of pearl is an extremely thin structure with organic elements less than 50 nm in size. The ID16A beam line at ESRF has provided us with an unprecedented opportunity to visualize mother-of-pearl in three dimensions, ”explains Igor Zlotnikov, Ph.D., Head of Research Group B CUBE. - The combination of electron-dense and high-periodic inorganic platelets with thin and thin organic surfaces makes nacre a complex structure for imaging. Cryo imaging helped us get the resolution we needed. ”

End station on the holographic X-ray nanotomography (ID16A) channel at ESRF. Credit: © Igor Zlotnikov

Analyzing the data was quite challenging. Исследователи разработали алгоритм сегментации с использованием нейронных сетей и обучили его разделять разные слои перламутра. Таким образом, они смогли проследить, что происходит со структурными дефектами по мере роста перламутра.

Cross-section of the shell showing the periodically layered mother-of-pearl over the prismatic structure of the shell. Credit: © Igor Zlotnikov

Behavior of structural defects in growingmother of pearl was unexpected. Defects in the opposite direction of the screw were attracted to each other from great distances. Right-sided and left-sided defects moved through the structure until they met and neutralized each other. These events resulted in synchronization throughout the tissue. Over time, this allowed the structure to develop into a completely correct and defect-free one.

Periodic structures like mother-of-pearlare created by many different kinds of animals. The researchers believe that the recently discovered mechanism could control not only the formation of mother-of-pearl, but also other biogenic structures.

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