Fluor‑carbonated hydroxyapatite coatings by pulsed laser deposition to promote cell viability and antibacterial properties

Fluorine, an essential element present in bone and dental tissues, promotes mineralization and is directly involved in the bone formation process. The antibacterial effects of fluorine on oral bacteria are also well known. In this study, metallic implants were coated with a thin layer of calcium phosphate enriched with fluorine to improve osteointegration and protect against infections. These coatings were obtained by pulsed laser deposition (PLD) using, as a target, a bioceramic of marine origin, mainly composed of fluorapatite from the enameloid of shark teeth. The compositional dependence of coatings on H2O vapor pressures applied during PLD was analyzed in order to optimize physicochemical properties. Physicochemical characterization to evaluate morphology (SEM), thickness (interferometric profilometry), structure (XRD) and composition (FTIR, XPS) was performed. To evaluate the biological response, both MC3T3-E1 pre-osteoblasts and bacterial strains Staphylococcus aureus and Staphylococcus epidermidis, most responsible for 77% of infections associated with prosthetic implants, were tested. Proper cell proliferation (MTT assay) and ALP synthesis up to 21 days were confirmed. Antibacterial properties were also demonstrated: compared to synthetic hydroxyapatite coatings, there was a significant reduction in colony-forming units (CFUs) for both strains.