title: Biomechanical and antibacterial properties of Tobramycin loaded hydroxyapatite coated fixation pins.
abstract: The present study investigates the use of nanoporous, biomimetic hydroxyapatite (HA) coatings deposited on TiO₂ coated fixation pins as functional implant surfaces for the local release of Tobramycin in order to prevent bacterial colonization. The impact of HA-coating thickness, coating morphology and biomechanical forces during insertion into synthetic bone on the drug loading and release properties are analyzed. The coatings are shown to exhibit bactericidal effects against Staphylococcus aureus in agar medium for a duration of 6 days after loading by adsorption with Tobramycin for only 5 min at elevated temperature and pressure. Furthermore, high performance liquid chromatography analysis shows a drug release in phosphate buffered saline for 8 days with antibiotic concentration remaining above the minimal inhibitory concentration for S. aureus during the entire release period. Biomechanical insertion tests into synthetic bone and conventional scratch testing demonstrate adhesive strength at the HA/TiO₂ interface. Biocompatibility is verified by cell viability tests. Outgrowth endothelial cells, as well as primary osteoblasts, are viable and firmly attached to both HA and TiO₂ surfaces. The results presented are encouraging and support the concept of functional HA coatings as local drug delivery vehicles for biomedical applications to treat as well as to prevent post-surgical infections.
authors.affiliation: Department of Pharmaceutics and Biopharmaceutics, Christian Albrecht University Kiel, 24118, Kiel, Germany.
authors.forename: Jan Henrik
authors.initials: JH
authors.lastname: Sörensen
authors.forename: Mirjam
authors.initials: M
authors.lastname: Lilja
authors.forename: Torben Christian
authors.initials: TC
authors.lastname: Sörensen
authors.forename: Maria
authors.initials: M
authors.lastname: Åstrand
authors.forename: Philip
authors.initials: P
authors.lastname: Procter
authors.forename: Sabine
authors.initials: S
authors.lastname: Fuchs
authors.forename: Maria
authors.initials: M
authors.lastname: Strømme
authors.forename: Hartwig
authors.initials: H
authors.lastname: Steckel
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D001858:Bone Nails; D002460:Cell Line; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000494:pharmacology; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D013211:Staphylococcus aureus / Q000254:growth & development*; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology; D014031:Tobramycin / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; C009495:titanium dioxide; D017886:Durapatite; D014025:Titanium; D014031:Tobramycin
keywords: Tobramycin; antibacterial; biomechanical properties; fixation pin; hydroxyapatite