Bioactive implant surface with electrochemically bound doxycycline promotes bone formation markers in vitro and in vivo.

OBJECTIVES

The objective of this study was to demonstrate a successful binding of Doxy hyclate onto a titanium zirconium alloy surface.

METHODS

The coating was done on titanium zirconium coins in a cathodic polarization setup. The surface binding was analyzed by SEM, SIMS, UV-vis, FTIR and XPS. The in vitro biological response was tested with MC3T3-E1 murine pre-osteoblast cells after 14 days of cultivation and analyzed in RT-PCR. A rabbit tibial model was also used to confirm its bioactivity in vivo after 4 and 8 weeks healing by means of microCT.

RESULTS

A mean of 141 μg/cm(2) of Doxy was found firmly attached and undamaged on the coin. Inclusion of Doxy was documented up to a depth of approximately 0.44 μm by tracing the (12)C carbon isotope. The bioactivity of the coating was documented by an in vitro study with murine osteoblasts, which showed significantly increased alkaline phosphatase and osteocalcin gene expression levels after 14 days of cell culture along with low cytotoxicity. Doxy coated surfaces showed increased bone formation markers at 8 weeks of healing in a rabbit tibial model.

SIGNIFICANCE

The present work demonstrates a method of binding the broad spectrum antibiotic doxycycline (Doxy) to an implant surface to improve bone formation and reduce the risk of infection around the implant. We have demonstrated that TiZr implants with electrochemically bound Doxy promote bone formation markers in vitro and in vivo.