Biomedical coatings to improve the tissue-biomaterial interface.

One of the most important factors determining the degree of tissue interaction of an implanted device is the property of its surface. Thus, great importance is given to chemical and morphological characteristics of biomaterial surfaces to improve biocompatibility, cell migration, proliferation and differentiation, mechanical stability and endogenous tissue ingrowth. In order to obtain new and healing stimulating properties, it is possible to apply a coating or more generally a surface treatment to the surface of a prosthetic device. One of the most versatile methods for coating is thermal spray technology. This paper considers the principle of thermal spray processes and their application in the biomedical field, namely the coatings used for orthopedic prostheses and dental implants. Among thermal spray processes, plasma spray as well as High Velocity Oxygen Fuel (HVOF) processes will be particularly considered and their most important aspects will be illustrated.

Phase-contrast imaging of thin biomaterials.

The necessity of information about the inner microscopical features of low absorbing materials is one of the most important goals in the structural research field. So far, non destructive analysis have been performed using contact radiography giving the scope for great advances in the production and application of new materials. However, the nature of interaction, namely X-ray absorption, limited the observations only to materials having sufficient heavy elements content. The adoption of a different X-ray interaction with matter which involves refractive properties of materials is at the basis of phase-contrast imaging. The novel method allows the use of high X-ray energies, for a deeper penetration and a lower released dose, without losing any information on the nature of the sample. A demonstration study, performed at the third generation European Synchrotron Radiation Facility (ESRF)-Grenoble, to show the potential of the new technique applied to biomaterials characterization is presented here. The test samples are a commercial matrix barrier (GUIDOR) intended to aid the healing process after periodontal surgery and a hydroxyapatite thin slab originally deposited by plasma spray technique on a TA6V alloy substrate. Phase-contrast images showed significant advantages revealing features that have negligible absorption contrast. The technique can be successfully used for the characterization of biomaterials.