Using a special form of the chemical vapour deposition, the so-called plasma enhanced chemical vapour deposition (PECVD), the researchers are able to produce biocompatible coatings with a thickness of just a few nanometres. On the one hand, the coating increases the adherence of desirable endothelial cells so that such implants take root particularly well in the body. On the other hand, the coating reduces the attachment of non-desirable smooth muscle cells. The new coating prevents the formation of plaques or aggressive cell growth.
„The special application technique from the gas phase allows not only the deposition of stents“, explains Cenk Aktas, head of the program division CVD/Biosurfaces. „We are working on a way to change this method and the composition of the coating so that we are also able to use them for heart valves or other implants on metal base, such as titanium“, says the materials scientist.
The procedure developed in Saarbruecken allows the surface of the implant to be structured by laser and then to be implemented in a plasma chamber filled with a special gaseous mixture. By ignition of the plasma, aluminium oxide or silicon oxide is deposited from the gas phase onto the surface of the implants, both as solid material. Using this procedure, the thickness of the coating is 30 nanometres. The coating is much more uniform than those made by other procedures, such as dip-coating.
For first tests, the researchers use an artificial pump system outside the human body. Human blood or blood substitutes circle through an artificial heart valve. Two coatings are added to the heart valve: a magnetic coating serves as a sensor in order to signalise how good or bad the heart valve closes. The protective coating is deposited over the magnetic layer in order to prevent the deposition of blood components. If there are many deposits on the heart valve, it closes badly. If there are no deposits on it, the heart valve closes well – the results are various magnetic signals measured in an external sensor. „With this combination, we can exactly determine which protective coating allows the heart valve to work longest“, says the project leader Aktas. The protective coating on the heart valve consists of adamantine carbonate. With a thickness of 100 millionth of a millimetre, the test system is mechanically comparable with the artificial heart valves existing so far.
Dr. Cenk Aktas
INM – Leibniz-Institut für Neue Materialien gGmbH
Head of the Program Division CVD/Biosurfaces
Phone: (+49) 681 9300 140
INM, situated in Saarbruecken/Germany, is an internationally leading research centre for innovative materials. Specialised in the three research fields of Chemical Nanotechnology, Interface Materials and Materials in Biology, the institute provides research and development from molecule to pilot production delivered by a highly skilled team of chemists, physicists, biologists, materials and engineering scientists. It cooperates with national and international institutes and develops materials with tailor-made properties for companies throughout the world. INM is an institute of the Scientific Association Gottfried Wilhelm Leibniz and employs around 190 collaborators.