Investigation of copper doped <i>β</i>-TCP and GB14 coatings produced via high velocity suspension flame spraying—a biocompatibility and antimicrobial activity study

Implant-associated infections and aseptic loosening of prosthesis due to insufficient secondary stability continue to present a challenging issue in arthroplasty. Potential solutions include bioactive coatings to promote osseointegration. With this in mind, this study aims to investigate and compare thin bioactive and bioresorbable<i>β</i>-tricalcium phosphate (<i>β</i>-TCP) and calcium alka-li orthophosphate (GB14) coatings, both produced via high velocity suspension flame spraying. To achieve an additional antibacterial effect and to prevent infections through aerosolized contamination, Cu-doped<i>β</i>-TCP supraparticles (SP) are incorporated into the coatings.<i>β</i>-TCP and GB14 coatings with 0.5 wt.% Cu-doped<i>β</i>-TCP SP each were investigated. According to ISO EN 10993-14, a degradation test was performed in TRIS-buffer at pH 7.4 over 120 h. Biocompatibility testing was performed on human osteoblasts using live/dead staining on days 1, 3 and 7 to simultaneously visualize viable and non-viable cells, while cytotoxicity was assessed over a 3 d period with the cytotoxicity assay. To evaluate the antibacterial efficacy, safe airborne antibacterial assays using<i>S. aureus</i>and<i>E. coli</i>were performed. Our investigations demonstrate that Cu is released from the coatings over a period of 120 h. The released Cu-amount results in a significant reduction in colony forming units across all coatings, while only negligibly imparing the behavior of the human osteoblasts. Both coatings exhibit high biocompatibility, with cell counts varying depending on the amount of Cu released. Cytotoxicity testing showed no cytotoxic effects for the samples examined.