Research focus: |
Forschungsverbund "Biomaterialien (FORBIOMAT II)"
Pleicherwall 2, 97070 Würzburg Mail: forbiomat@fmz.uni-wuerzburg.de Url: |
Scientific members:
Professors:
Scientific assistants:
Research foci (and basic equipment-based research projects):
Structuring and/or functionalization of materials for medical devices in long term contact to the human body
Results:
Bavarian Research Cooperation Biomaterials (FORBIOMAT II)
The second research and development period of the Bavarian Research Cooperation Biomaterials (FORBIOMAT II) ends with the year 2002, just like the complete Research Cooperation. The cooperation was started from a competent surrounding field, following the idea of the initiator Ltd. Ministerialdirigent J. Grosskreutz of the Bavarian State Department for Science, Research and Art. The cooperation is terminated after 5 years of successful research and development at universities and companies. Emphasis of the projects was the improvement of technologies for the manufactering and commercializing of implants for the replacement of functions, which are lost through degenerative deseases. The most important ranges of application were joint implants locomotion system, dental implants and arterial ?stents".
FORBIOMAT II focussed its attention on surface modifications, in order to improve implants close to the requirements of implantation site. Altogether seven projects with different goals were supported by the Bavarian State Department, which however were intensively networked due to the goal of the cooperation. The support amounted conveyance sum out of ?the High Tech offensive Bavaria "amounted to DM 3.4 millions or approxemately ? 1.6 millions covered by the Bavarian High Tech Offensive.
In detail the following research and development projects could be successfully finished:
Development of diamond-coated femural sliding surfaces for knee joint prostheses (Professor Dr. R. F. Singer)
The expectations to the tribological properties of the surface modification were fulfilled. Homogeneous coatings could be realized also for complex component geometry by the development of a filament holder within the coating apparatus. In an animal model, the diamond-coated titanium implants showed compared to uncoated surfaces identical biocompatibility. The success of the project is shown by the spin-off of company DiaCON GmbH, which brings the scientific results via improved medical devices into the market.
Anti-infectious and/or. bacteriostatic coatings of cement-free implanted endoprostheses (Prof. Dr. A. Stemberger)
Anti-infectious coatings should be realized by incorporation of antibiotics. The custom-made antibiotic therapy is of importance with regard to the avoidance of the formation of multi-resistant bacteria stems. Therefore an antibiotic was incorporated in the coating, which is considered as reserve antibiotic against multi-resistant germs.
After contact with the coated implant bacteria growth is nearly completely prevented by the antibiotics. Due to the small concentration of the locally applicated active substances and the protracted release behavior it can not be bargained for a systemic load in the organism. The procedure not only opens new possibilities for the therapy of infected endoprostheses, but can also be understood as preventive method for a drastic reduction of the infection rate in the future.
Improvement of the implant biocompatibility by coating stainless steel implants with tantalum (oxide) and a delayed degradable collagene structure (Professor Dr. M. Nerlich)
Fracture healing needs metal implants for stabilization. The project led to surface modifications of stainless steel implants, which increased the corrosion resistance by a dense coating of tantalum and/or tantalum oxide. Mechanical interlocking with a crosslinked collagene structure served as a soft part stabilization and an improved conditioning for the healing process. Adhesion promoters and coupling agents act as a covalent linkage between tantalum oxide and collagene. The degradation behavior can be adjusted as a function of the cross-linking of the collagene as well as of the cellular adhesion, proliferation and differentiation.
Improvement of the long-term behaviour of textile implants and other polymer based biomaterials by plasma-activated chemical vapor deposition (PACVD) (Professor Dr. D. E. Birnbaum)
The project supplied polymers, whose biocompatibility and long-term stability took place via a new surface modification with titanium containing coatings. The titanium carbonitride coatings are featured by a nearly substrate-independent composition and a high adhesive strength. High wettability and surface tension ensure the biocompatibility and are a condition for a better cell adhesion of human endothelial cells and fibroblasts. Compared with uncoated polymers a higher cell proliferation and vitality was reached. The function of the human endothelial cells was essentially not influenced. However, no improvement could be observed in the animal model so far. At present, the higher biocompatibility is still connected with a stronger bacterial adhesion.
Development and manufacturing of surface-modified, cardial stents for the improvement of biocompatibility and function (cardial stent) (Professor Dr. R. Thull)
Cardial stents are made from implant steel due to mechanical and technical reasons. The material is standardized for applications within the human body. The existing corrosion bahavior of steel in the physiological environment was improved by surface modification with a tantalum / tantalum oxide coating system. The system is fabricated by a primary tantalum implantation following a physical vapor deposition process with reproducible properties. Although only a thin layer modification on steel was realized, the system proves mechanical stable, also during stent dilatation in the blood vessel. The primary tantalum implantation causes repassivation after activation due to defects. Tests on cell compatibility and on allergological / immunological potencies showed compared to steel improved results compared to stainless steel. The investigations were performed project overlapping. The surface modification leads to a stimulation of the thrombine generation in a screening test. The technology has reached a production-ready state.
Plaque-resistant dental materials (Professor Dr. G. Schmalz)
In this research project bacteria adhesion-inhibiting materials were developed by addition of polyalkenoate particles to commercial dental composites. A slight admixture did not affect negatively shrinking behavior, bending strength, elastic module, compressive strength, surface hardness, Vickers -, universal and plastic hardness. The abrasion was only slightly increased. Cell compatibility and mutagenicity of the materials were alike or smaller than comparable products, just like the in vitro bacterial adhesion. The wetting with saliva had a levelling influence on the bacterial adhesion. No influence of the polyalkenoate particles on the plaque formation was accounted for in vivo, however a significant influence of the saliva wetting on the surface tension. The test materials show toxicological and material-technically good results. Since the bacteria adhesion could be improved only slightly, the bacteria adhesion material did not find industrielle utilization.
Allergological- immunological aspects of the optimization of long-term applicated materials in the human body (Dr. P. Thomas)
The project was accomplished parallely for all material developments within the FORBIOMAT research cooperation by the clinic and policlinic for dermatology and allergology at the Ludwig Maximilians University Munich. The materials of all projects were tested in the study.
The materials were examined in solution with human peripheral - blood leukocytes for allergological potency. Most important results were: During testing of diamond-coated/uncoated titanium specimen (project: Professor Dr. R. F. Singer), no inhibiting influence on the lymphozyte activity was shown, as well no immune activation with increased IL-4 or IFN g expression could be observed. Treated and untreated stainless steel specimen (project: Professor Dr. A. Stemberger) did not show differences with blood cells of normal persons; stimulation of the cells of nickel-sensitive patients showed themselves a weak proliferation increase with coated materials. Coated and uncoated titanium samples showed same results. In co-culture with tantalum-treated and untreated stainless steel (project: Professor Dr. R. Thull) a rather inhibiting effect was recognizable in direct contact to untreated compared to treated steel samples.
The Bavarian Research Cooperation Biomaterials (FORBIOMAT), initiated by the Bavarian State Department for Science, Research and Art, supported from ?the High Tech - Offensive Bavaria" in the second part, results in an important progress within the range of the user-specific material modifications for implants. A network of co-operating university institutes and -clinics and medium-size companies was established. Besides the financial support of the Free State of Bavaria improved the infrastructure for research and development within the institutes and clinics beyond the existing good conditions.
The competence network within the range of the functional materials for the application in the human body is continued in the future, in order to start up a private-economically project management company. A business plan was compiled likewise supported by the Free State. Besides the project management, task of the company will be the expert advice of investors, who will engage themselves in the support of small and medium-size companies in the range of medical technology.
All university departments and -clinics and the involved companies, summarized in the Research Cooperation FORBIOMAT, thank the Bavarian State Department for science, research and art for the important financial support. Also enclosed into the thanks are the reviewer for the cooperation programme as well as Ltd. Ministerialdirigent J. Grosskeutz as the initiator of the Bavarian Research Cooperation Programme and Ministerialrat Ch. Schuberth with coworkers for the constant conveyance and support of the projects.