bionic hip joint designs through biomimetics

Skilled builders
 Hip joints like this are made of metal alloys and artificial materials. Jena materials scientists have a vision, but even being able to produce in the laboratory of natural materials - on the basis of proteins. Photo: Roland fruit
Jena material scientists want to crib secrets of nature to create in the laboratory even universal biological building blocks. With proteins they succeed to some extent already.
Jena. Whether the knee joint, knuckle or an entire hip, whether ossicles, metallic mesh scaffolding, the ailing blood vessels based or heart valve, the list of "spare parts" that man has developed in order to keep his body longer functional, is quite long. The grafting of artificial joints has become routine, the insertion of stents and bypass surgery for heart and circulatory problems as well. In close cooperation to develop medical and materials scientists are better implants, which are not rejected by the body as foreign, but complications quickly and grow into the body's own tissues.
"Materials science and medicine have come a long way here," says Prof. Dr. Klaus D. Jandt, Chair of Materials Science at the University of Jena. "But again, these are for man-made materials. Our dream is to have materials available that match those of nature." To make this dream a reality, it is at the Institute of Jandt worked for five years with hypertension. And with success.
The branch of science on which the researchers move it has a name: bionics. Jandt also referred to as biomimetics, because "we are inspired by nature," explains the scientist. The building, which the researchers are experimenting with his team here, are proteins, ie proteins.
"Proteins are extremely versatile. If you consider that the biota combined 22 amino acids into the thousands of different proteins that have very different properties and functions that they it is building high-strength structures, as it still is not the man to now dominates, then is one of the pressing comparison with Lego building blocks from which one can build anything with "said Jandt the fascination of the proteins.
He cites the example spider silk. The threads that synthesize proteins from the insects are up to five times stronger than steel. For an example of extreme Jandt effectiveness in terms of material usage and results. Or blood clotting. "A blood vessel is injured, starts a complex biochemical reaction, up to 15 clotting factors are activated at this time to stop bleeding and to close a wound. A very important function of this protein fibrin and its thread-like soluble precursor fibrinogen has," said Jandt . Fibrinogen strands join together to branch out and eventually form a stable three-dimensional network. "This makes these devices very interesting," said Jandt, who was honored for his work on the interaction of fibrinogen with structured material surfaces in February with the Thuringian Research Award for Applied Research.



"There are not the multi-tiered and multi-faceted nature of the instruments in blood clotting is available, we have to go other ways," he admits. The Jena have found an easier option: they work with fibrinogen dissolved in water and mixed with this alcohol. "In this solution, the fibrinogen forms fine threads which form a diameter of two to ten nanometers." A human hair is about ten thousand times thicker. In the laboratory, the researchers have been able to make two-dimensional networks of these threads. Push forward with the nanofibers in the third dimension seems possible.
Scientists already know how to give more strength to their networks. "In a liquid, the liquid is similar to the body, we have mineralized the fibrinogen fibers with hydroxyapatite, a material that is present in our teeth and bones," says the researcher. This is certainly only a precursor of bone formation. "But here we could build hierarchical materials, just as nature does this," he noted. The benefits are obvious to him: These natural materials are fully biodegradable.
 Prof. Klaus Jandt with a model of fibrinogen, which is "spun" into filaments in its laboratories and networks. Photo: Angelika mold
The filaments produced in the laboratory, the scientists are also the secret of their biological model continued on the track. "Our focus in the development of implant materials or materials for the food industry is already long on the surfaces of materials," said Jandt the relationship. "We know that if an artificial material comes together with a natural, no direct interaction between these materials. Rather, proteins are always the mediator." So far, however, is not known how the functioning. However, knowing this was important in all areas where synthetic materials come into contact with living organisms in water treatment in biogas plants in the food industry and medicine.
Enlightenment hope for the Jena bionics researchers with the help of their fibrinogen strands. These should be introduced into cells loaded with fluorescent dyes in order "to make visible what is happening and how proteins attach themselves." The next step would be to test the compatibility of the natural material from the lab with cells of the body, looks ahead Jandt.
Such research does not only time but also money. So far, the bionics research was supported by grants from the Carl Zeiss and Alexander von Humboldt foundation. For the future, the Jena materials scientists hope to further promote the country and the German Research Foundation. "Bionics is promising to develop new materials with amazing properties," says Jandt. But even internationally a "hot box". In research with natural proteins, the Jena currently have a head start. Want to expand it.