Co-precipitation of Tobramycin into Biomimetically Coated Orthopedic Fixation Pins Employing Submicron-Thin Seed Layers of Hydroxyapatite
Jan H. Sorensen, Mirjam Lilja, Maria Astrand, Torben C. Sorensen, Philip Procter, Maria Stromme and Hartwig SteckelAffiliation:
Division for Nanotechnology and Functional Materials, The Angstrom Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden.
AbstractThe migration, loosening and cut-out of implants and nosocomial infections are current problems associated with implant surgery. New innovative strategies to overcome these issues are emphasized in today’s research. The current work presents a novel strategy involving co-precipitation of tobramycin with biomimetic hydroxyapatite (HA) formation to produce implant coatings that control local drug delivery to prevent early bacterial colonization of the implant. A submicron- thin HA layer served as seed layer for the co-precipitation process and allowed for incorporation of tobramycin in the coating from a stock solution of antibiotic concentrations as high as 20 mg/ml. Concentrations from 0.5 to 20 mg/ml tobramycin and process temperatures of 37 °C and 60 °C were tested to assess the optimal parameters for a thin tobramycin- delivering HA coating on discs and orthopedic fixation pins. The morphology and thickness of the coating and the drug-release profile were evaluated via scanning electron microscopy and high performance liquid chromatography. The coatings delivered pharmaceutically relevant amounts of tobramycin over a period of 12 days. To the best of our knowledge, this is the longest release period ever observed for a fast-loaded biomimetic implant coating. The presented approach could form the foundation for development of combination device/antibiotic delivery vehicles tailored to meet well-defined clinical needs while combating infections and ensuring fast implant in-growth.
Co-precipitation, tobramycin, hydroxyapatite, biomimetic coating, drug release.
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