Investigation of antibacterial hydroxyapatite-copper coatings applied by high-velocity suspension flame spraying

Bacterial contamination and biofilm formation onto implants are one of the most serious postsurgical complications. Preventing the bacterial formation is the key to limiting such implant-related infections (IRI) and to achieving a high success rate in implant treatment. Thus, an increased interest of antibacterial coatings has emerged in recent years. In this paper bioactive and antibacterial hydroxyapatite-copper (HApCu) coatings have been sprayed using high-velocity suspension flame spraying (HVSFS). Two water-based suspensions were developed with copper (Cu) and hydroxyapatite (HAp) powders, respectively. First, the oxidative behaviour of copper during spraying was investigated and optimized using radial injection into the open flame. Emphasize was set on a minimized oxidation content to ensure good antibacterial properties. Second, a co-injection of radially Cu and axially HAp was conducted in order to produce bioactive and antibacterial coatings with a copper content of < 2%. The coatings were further optimized towards improved osteointegration with the surrounding tissue by increasing the porosity and adjusting the surface roughness. First results of the bioactive and antibacterial properties of the fabricated coatings were studied in-vitro using simulated body fluid (SBF) assessment.