Prof. (apl.) Dr. Reiner Dahint – Biosensors and Biomaterials Research Group

In the last decade, the search for biocompatible materials has become a major topic in medical research. In addition to biocompatibility aspects, the development of movable and mechanically stressed implants, such as artificial joints, requires optimization of lubrication under shearing forces and pressure. As in state-of-the-art artificial joints the movable parts directly touch each other, resulting in high friction and potential damage of the contacting parts, researchers nowadays try to copy the principles of lubrication observed in natural joints. Here, the two opposing components are coated by cartilage and surface-active lipids, and separated by a liquid film, the so-called the synovial fluid. All three compounds are expected to play an important role in the reduction of friction.

Using model systems consisting of a solid support, coated with a lipid layer and exposed to hyaluronic acid solutions - the main component of the joint fluid, we work on an improved molecular understanding of the effects of pressure and shear on such soft solid/liquid interfaces. In particular, neutron reflectometry and surface sensitive infrared spectroscopy (ATR-IR) are employed to reveal associated structural changes, investigate film stability and detachment under external stimuli, and work out structure/function relationships. Beside lubrication issues, such pressure and shear dependent studies can be applied to a variety of problems and applications, e.g. the stability and energetics of lyotropic lipid mesophases, the behavior of natural organisms under extreme conditions as in deep-sea marine biotopes, and the improvement of biotechnological procedures like high pressure food processing.