'Egg shell' technology for stronger bones
NUS SCIENTISTS at the Materials Research Lab in the Department of Chemistry often marvel at how nature is able to construct an egg shell that contains pores which act as "windows" for oxygen and carbon dioxide to flow freely – and yet would not weaken the structure. Since 1998, they have been trying to uncover nature's technological know-how and mimic them in the laboratory. Today, they have successfully re-constructed a synthetic egg shell in the laboratory. The team led by Assoc Prof Suresh Valiyaveettil, with collaboration with the Departments of Biological Sciences and Physiology, uses a process known as "reverse engineering" to unlock nature's technology – through sequential analysis of the egg shell's function, structure and constituents.
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| REPLICATING NATURE: Assoc Prof Suresh Valiyaveettil (left) and his team of scientists at the Materials Research Laboratory has successfully re-constructed a synthetic egg shell. |
What gives the egg shell its hardy strength is calcium carbonate – a common substance found in rocks. The team found that calcium carbonate made up almost 98 per cent of an egg shell. The remaining two per cent comprises proteins which act as the "cement" to hold the calcium carbonate together.
"Calcium carbonate acts as the bricks for construction of the house. But bricks alone can't build a strong house. You need cement to hold these building blocks together to form a mechanically strong structure," said Assoc Prof Suresh.
In a landmark discovery, the team found a new protein ansocalcium which is a crucial adhesive. Analyses were then conducted to determine the optimum composition of the protein and calcium carbonate, as well as the optimum temperature and other conditions necessary to re-create the nature's construction of the egg shell in the laboratory. The resulting synthetic shell currently only has the strength of about 10 per cent of a real egg shell, but the team is only about one year away from optimising its strength.
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| FUTURE THERAPY: Understanding the intricacies of nature’s construction of egg shell could pave the way for treating accelerated bone loss in human. |
Assoc Prof Suresh said understanding the intricacies of nature's construction of egg shell could pave the way for treating accelerated bone loss in human or osteoporosis. Just like construction of egg shells, human bone regeneration takes place via the process of mineral disposition.
"If we can determine the protein which is responsible for the process, the level of such protein in human body could be increased to reverse bone loss," said Assoc Prof Suresh.
Farmers can also use feeds with optimum level of calcium carbonate and proteins to enable their poultry to produce stronger eggs. That would translate into fewer breakages and cut down loss of revenues. The same principle can also be applied to increase the survivability of embryo in eggs belonging to endangered animals.
Turtle eggs
Assoc Prof Suresh's team is also conducting study on turtle eggs. Unlike birds which lay their eggs on nest, turtles bury their eggs in hundreds under the sand on beaches. This meant that the "house" requires a different "architectural" design. Hence turtle eggs are soft and coated with mucous to withstand the massive weigh of sand and other eggs over an extended period of time. The team is researching on how turtle eggs can be soft and strong at the same time.
His team is also looking into the construction of starfish bone – on how its bone can harden and soften at will. Other similar projects include the study of giant clam shell and sand dollar, a marine animal similar to sea urchin. These studies have been supported by A*STAR.
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