You are here: MEDICA Portal. Part IV: Substances. Nanotechnology.
Material Rush Hits Medicine (Part 2)
Part 2: Biosilicates from the Abyss
It is because of a very special polymer why Werner Müller disappears a few hundred meter underneath the chinese sea. The molecular biologist of the University of Mainz in Germany is searching for new materials for medicine – and throws a glance into the sea looking for sponges, soft tissued animals that live on reefs and stones all over the world and filter water to feed.
A sponge: A glassfabric
located in the sea
© Werner Müller
He is interested in their skeletons made of silicium dioxide, the main component of glass. „The animals produce glass being surrounded by cool sea water, spicular structures with thorns, knobs or small globes“, Müller explains. Humans nees very high temperatures and toxic chemicals in order to achieve this - the sponge seems to just use its genes.
And as a matter of fact Müller and his colleagues discovered a sponge protein and on top of that a totally new process in nature: an anorganic polymer - glass - is being created with the help of an organic enzyme. „Nobody ever observed something like this“, Müller says. Now, the enzyme has been patented and the scientists hope to use it for biotechnological applications, for example in order to manufacture biomaterials for the cultivation of bone tissue or for implants made of titanium that will not be recognised by the body as foreign material anymore. The idea is to cover the implant with the sponge enzyme resulting in a sheath of biosilicates that is not going to be recognised and in turn be repelled by the human body's immune system.
Sponges communicate like telephone companies
However, sponges seem to be capable of more: The glas filaments belonging to the skeleton have the same high quality as glass fibres used for telecommunication.
The sientists have observed that the sponges use a certain quality of light, they use their glass fibres as some kind of nano fibre in order to transport just one wavelength and they therefore "hypothesize that sponges communicate with light". If you pinch the animal it flinches – even though it does not have a nervous system. "The stimuli arrive", Müller says. The sponge's glass fibre in terms of an extraordinary nerve tract may provide totally new approaches for research.
Travel to the Moon and back with Nanotubes
The scientific world hoped for totally new approaches also with carbon nanotubes (CNTs). „In theory, a single nanotube possesses so much inert strength that it would be imaginable to stretch a rope from Earth to the Moon in order to get an elevator getting up and down“, Uwe Vohrer says, doctor of the Fraunhofer Institute for Interfacial Engineering and Biotechnology. Visionary ideas boomed when these tiny tubes were discovered about ten years ago.
CNTs exhibit very special properties: They are light, have a special electrical conductivity, are mechanically stable. „We thought that CNTs being incorporated into other materials could render materials with new properties too“, says Vohrer. However, the properties of a sibgle fibre just represents half of reality. That is why the initial euphoria went soon and material scientists now are studying CNTs thoroughly.
This is especially important for medicine since a few years ago everybody thought that these tubes could not be harmful for the body since they are just made up of carbon - just in nanosize. But they may be toxic after all because of their tiny size since they may be capable of penetrating deeply into the body or may be due to contaminants during manufacturing of nanotubes. „Comparing them to toxic asbestos is valid only to a limited extent“, Vohrer explains. „Only CNTs of a very defined length cause irritations in the abdominal cavity of mice.“ None the less, the new materials need to checked carefully before being applied in humans.
Use of CNTs outside the human body is part of Vohrer's and his team's research: They are trying to culture bone marrow cells on bucky paper, ultrathin paper made up of nanotubes, in order to then implant the cells in the body. „We are also working on using CNTs as an artificial muscle in order to move a prostheses outside the body“, Vohrer explains. The theory behind the idea is based upon the tiny tubes behaving similar to human muscle when they move. Therefore, they could theoretically take the muscle part of a hand prosthesis. The problem ist that this only works on a scale of micrometers yet - the fibres are needed on a centimeter scale though.
There are obviously still many technical difficulties. „However, CNTs have a future“, Vohrer is convinced. „They are called one of the important materials of the 21st centuries since there are so many application areas for them.“ If it was not possible to find any within medicine, the CNTs were at least suitabel for other areas - already they are being worked into barrels to prevent them to get an electrical charge so that explosives can be transported safely.
- Part 1: Material Rush Hits Medicine
- Part 2. Biosilicates from the Abyss
- Part 3: Transistor at Nanolevel