Wednesday , January 27 2021

Imitation of skeleton reveals how bones grow atom by atom



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Image: How the researchers imitated the formation of the natural bone: strings of liquid crystals made of polymers act as strings of collagen in the body. Amorphous calcium phosphate (gray) enters …
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Credit: Anand Kumar Rajasekharan / Chalmers University of Technology

Researchers from the University of Mars, Sweden, have discovered how our bones grow at the atomic level, and show how an unstructured mass is arranged into a perfectly ordered bone structure. The discovery offers new insights, which can yield improved new implants as well as increasing our knowledge about bone diseases such as osteoporosis.

The bones in our bodies grow in several stages, with atoms and molecules joining together, and the larger groups joining together. One early stage in the growth process is when calcium phosphate molecules crystallize, which means they are transformed from an amorphous mass into a neat structure. Many stages of this transformation have been a mystery in the past, but now, through a project that reflects the way our bones are structured, researchers have been able to follow this crystallization process at an atomic level. Their results are now published in the scientific journal Communication Nature.

"Our project originally focused on the creation of artificial biological material, but the material proved to be a great tool for learning bone-building processes, first we imitated nature by creating an artificial copy, and then we used the copy This to re-learn the nature, "says Martin Anderson, professor of chemistry and materials at Mars, and lead researcher.

The researchers developed a method for creating an artificial bone using additive production, or three-dimensional printing. The resulting structure is built in the same way, with the same characteristics, as real object. After full development, it will allow the formation of naturalistic implants, which can replace the metal and plastic technologies used. When the team began mimicking natural bone tissue functions, they saw that they had created the possibility to study the phenomenon in a environment very similar to the environment in living tissue.

The bone-like material of the group mimicked the way the real object grew. The skeleton's smallest structural building blocks are groups of strings composed of protein collagen. To mineralize these strings, cells send out spherical particles known as vesicles, containing calcium phosphate. These blisters release calcium phosphate into closed areas between the collagen strings. There, calcium phosphate begins to transform from an amorphous mass into a parent crystalline structure, which creates the characteristics properties of the bone's unusual resistance to shocks and bending.

The researchers followed this cycle with the help of electron microscopes and now show in their paper how it happens at the atomic level. Despite the fact that bone formation occurs naturally in a biological environment, it is not a biological process. Instead, the physical properties of calcium phosphate define how it crystallizes and develops, following the laws of thermodynamics. Molecules are drawn to the place where the lowest energy level, and as a result it builds itself into a completely crystallized structure.

"With the electron microscope, we can follow the stages of how the material has become a neat structure, enabling it to achieve as low a level of energy as possible, and therefore a more stable state," said Dr. Antopia Lutsari, a researcher at Martin Anderson's group who conducted the experiments with an electron microscope.

The Chalmers researchers are the first to show high resolution what happens when the bones crystallize. The results can affect how many common bone-related diseases are treated.

"Our results may be significant for the treatment of bone disease such as osteoporosis, which is now a common disease, especially among older women. Osteoporosis is when there is an imbalance between some rapidly breaking and regenerating bones, which are natural processes in the body," says Martin Anderson.

New drugs for osteoporosis, which work through the effect on this imbalance, can be improved with this new knowledge. Hopefully, more precisely, we can assess the pros and cons of existing drugs, as well as experimenting with different substances to examine how they interfere with or stimulate bone growth.

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The article "Transformation of Amorphous Calcium Phosphate to Bone Apatite" was now published at Communication Nature.

For more information contact:

Martin Anderson

Professor of Surface Applied Chemistry,

Department of Chemistry and Chemical Engineering

University of Mars, Sweden

[email protected]

+46 31 772 29 66

Antisopi Lutsari

Postdoctoral researcher

Department of Chemistry and Chemical Engineering

University of Mars, Sweden

[email protected]

+46 31 772 30 28

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