Bioactive coatings on silicone catheters

Materials for bioactive coatings of implants, which harmonize with the chem ical properties of the cell surfaces and so create a firm connection betwee n implant and tissue, are increasingly needed in order to create more bioac tive implant surfaces. Hydroxyapatite (HAp) has approximately the same comp osition as human bone. Silicone catheters are inserted because of their goo d compatibility with blood, but the growth of skin cells is prevented, so a hydroxyapatite coating is charged with providing a surface to which skin c an grow, thus reducing the risk of infection in percutaneous applications. The HAp coating is produced by precipitating a layer out of a saturated cal cium phosphate solution. The precipitation parameters pressure, temperature , pH and time influence crystallization, form and layer thickness. Final in vitro investigations judge the degree of biocompatibility.