An international research group led by Prof. Boaz Pokroy of the Technion deciphered the process of formation of hard and durable substances in the bodies of marine organisms
How do marine organisms produce hard tissues such as armor and optical lenses from the materials available to them and under the hostile conditions prevailing under the waves? This is what a study by an international group is leading Prof. Boaz Pokroy and doctoral student Nofar Bianco-Stein from the Faculty of Materials Science and Engineering. The study was conducted with Dr. Catherine Dajoy from ESRF – the European Synchronon in Grenoble, France.
In a recent study published in PNAS, the scientists focused on the involvement of magnesium-containing calcite in the said processes. Magnesium is a strong and light metallic element that plays many roles in the animal world, including the human body. Calcite, and in Hebrew calcium carbonate, is a very common mineral that makes up about 4% of the Earth’s crust mass. This material is an essential ingredient inBiomineralizationThat is, in the process by which organisms, from the materials available to them, produce various structures – pearls, bones, armor and so on.
“Biomineralization processes,” explains Prof. Pokroi, “produce structures that surpass in many respects, such as strength and resistance to fractures, artificial products of engineering processes. Engineering in a variety of fields. “
In the biomineralization process the organism uses various strategies to produce strong structures such as an external skeleton. Technion and ESRF scientists show in their article that one of the common strategies in this regard is Precipitation of magnesium-rich nanometer calcite particles Inside a low-magnesium substrate. According to Prof. Pokerroy, “We have discovered that this phenomenon occurs in a huge variety of creatures, even creatures from different kingdoms in the animal kingdom, and we estimate that it is even broader than we have discovered. It is therefore likely to be a very evolutionarily preserved (ancient) phenomenon.”
In the present study, the researchers focused on nine different organisms including sea urchins, red algae, starfish, coral and sea urchins. The two main players in the process are as mentioned magnesium and calcite. The researchers found that the precipitation of the calcite particles in a low-magnesium substrate creates compression efforts in the skeletons that increase their rigidity – without the need for mechanical compression used in the production of similar materials in artificial engineering processes.
In Nachshon the sea The unique crystallization process takes place in the lenses scattered on his arms – a kind of primitive eyes but effective for his needs. These lenses, which are similar in nature to tempered glass, focus sunlight on nerve centers that transmit information to the rest of the body through the nervous system. In contrast to the tempered glass that man produces at high heat and under pressure, the Nachshon lenses are manufactured at the given water temperature and without external mechanical pressure other than the water pressure. An important step in this process is the transition of the calcite from an amorphous (disordered) phase – to the ordered crystalline phase.
The red algae That international team research are algae common in shallow water, where they are subject to external pressures of sea waves and therefore must be resistant to tearing and fracture. Therefore, their cells are coated with the same strong nanoscale crystals of magnesium-calcite. These crystals form hollow micro-structures that increase their strength and durability.
Although the sea urchin and red algae are very different creatures, they exhibit common structural aspects including the same crystallization of strong structures in the process of sedimentation of magnesium-rich nanometer crystals in a substrate characterized by low magnesium levels.
The researchers found that this crystallization process improves both the hardness of the material and the resistance to fractures. Moreover, they show in the article that even a slight reduction in the magnesium content in the substrate Multiplier The hardness of the material by about 100%.
The study was supported by an ERC grant and was conducted in collaboration with Synchrotron Grenoble in France and Argonne National Laboratory in Illinois.
For an article in the journal PNAS
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