Thin Degradable Coatings for Optimization of Osteointegration Associated with Simultaneous Infection Prophylaxis

One of the most common causes of implant failure is aseptic prosthesis loosening. Another frequent complication after prosthesis implant is the microbial colonization of the prosthesis surface, which often leads to a replacement of the prosthesis. One approach to reduce these complications is the application of bioactive substances to implant surfaces. Both an antibiotic prophylaxis and a faster osteointegration can be obtained by incorporation of bactericidal active metals in degradable calcium phosphate (CaP) coatings. In this study, thin degradable calcium phosphate ceramic coatings doped with silver (Ag), copper (Cu), and bismuth (Bi) on a titanium substrate were prepared with the aid of the high-velocity suspension flame spraying (HVSFS) coating process. To characterize the samples surface roughness, brightfield microscopy of the coatings, X-ray diffraction (XRD)-analysis for definition of the phase composition of the layers, Raman spectroscopy for determination of the phase composition of the contained metals, element-mapping for Cu-content verification, release kinetics for detection of metal ions and ceramic components of the coatings were carried out. The aim of this study was to evaluate in vitro biocompatibility and antimicrobial activity of the coatings. For biocompatibility testing, growth experiments were performed using the cell culture line MG-63. Cell viability was investigated by Giemsa staining and live/dead assay. The WST-1 kit was used to quantify cell proliferation and vitality in vitro and the lactate dehydrogenase (LDH) kit to quantify cytotoxicity. The formation of hydroxyapatite crystals in simulated body fluid was investigated to predict bioactivity in vivo. The Safe Airborne Antibacterial Assay with Staphylococcus aureus (S. aureus) was used for antimicrobial testing. The results showed good biocompatibility of all the metal doped CaP coatings, furthermore Cu and Ag doped layers showed significant antibacterial effects against S. aureus.