Due to material-related deficits in specific surface properties, the materials used in biotechnology, medical technology, and pharmaceutical materials require the use of different technologies for surface modification. In recent years plasma technology has become a key technology for medical and biological applications. In this regard, the application spectrum of surface modification extends from the area of implants to complete infusion systems, including valves and catheters. Other focus areas are modification of services for immobilization of enzymes, bacteria or cells, as well as providing biomaterials with antimicrobial properties in order to effectively protect surfaces against pathogenic infestation.
The spreading of pathogenic microorganisms is omnipresent and difficult to prevent, even with the most stringent hygienic measures and frequent disinfection measures. In particular, multi-resistant germs are a major problem today Consequently hygiene plays a central role in health-sensitive areas, such as hospitals and medical practices. Accordingly, the requirements for excluding the possibility of contamination are high. Surfaces that have an antimicrobial effect can make an essential contribution toward solving this problem.
Through use of plasma-based or sol-gel based coating procedures properties with an antimicrobial effect can be generated. To avoid resistances, such as occur through use of antibiotics, or to kill off bacteria that have already developed a resistance, among other things metal ions (especially copper or silver) or transition metal oxides (for example, molybdenum trioxide) can be incorporated in the material surface or applied as a coating. Through these measures, germ-free services can be produced that are effective against a variety of bacteria, viruses and fungi.
Through plasma-induced surface modification of biomaterials, according to the composition of the process gas used, protein adhesion and cell adhesion can be selectively controlled – positively (cell attracting) or negatively (cell repelling). One focus area is generation of bio-relevant surface properties of implant materials, with the aid of specially tuned plasma processes. Rapid acceptance by the surrounding tissue is crucial for integration of an implant or bone replacement material. In this regard the boundary surface between biomaterial and bone plays a decisive role. Selective optimization of adhesion, migration, and proliferation of the body's own cells on the boundary surfaces should cause improved ingrowth, a reduced risk of infection, and an increase in the stability of an implant. Inversely however, via plasma treatment the adhesion properties of surfaces can be controlled in such a manner that the linking of cells or microorganisms is inhibited. For example this is a great advantage for temporary implants.
Adhesion of bacteria and cells on biomaterials is also controlled through the morphologic surface shaping, among other things. Currently there are various methods for either reducing surface roughness or for selectively structuring the surface. For example, the plasma polishing method offers a number of advantages in one process step. In the manufacturing of medical products, process-related burrs and residues occur on edges and surfaces that can impair compatibility relative to tissue and cells. Through plasma polishing these surfaces can be deburred with controlled stock removal. Additional applications are decoating, improvement of corrosion protection r friction reduction, as well as hydrophilization of different materials and alloys. On the other hand, the plasma spraying method enables deposition of porous, bioactive coatings that favor bone integration through ingrowth of the bone tissue, and consequently the clamping and intermesh of the implant with the bone (e.g. endoprosthesis).