Dissertation Christiane Petzold
Dipl.ing. Christiane Petzold will defend her thesis UV-induced functionalization of titanium surfaces with a polyunsaturated fatty acid for improved performance of temporary bone fixation devices.
UV-induced functionalization of titanium surfaces with a polyunsaturated fatty acid for improved performance of temporary bone fixation devices
Titanium (Ti) implants with smooth surfaces lower the bone-to-implant attachment strength, allowing for retrieval of temporary implants without impairing the newly formed bone. The formation of a layer of fibrous tissue around the implants with in reduced stability of the fixation and negative effects on bone healing disfavors the use of smooth surfaces. We developed and tested an UV-induced chemical surface coating of smooth Ti with the n-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) as a means to prevent strong bone-to-implant attachment, maintain or increase the formation of new bone, and reduce the attachment or survival of S. epidermidis on those surfaces.
UV irradiation of the Ti surfaces reduced the carbon content, made them superhydrophilic, and generated reactive Ti-OH groups. EPA was photooxidized by irradiation with UV light. By irradiating Ti surfaces and EPA with UV light, reactive groups were formed on Ti surfaces and EPA, making it possible to obtain a thin layer of chemically bound EPA molecules as could be shown by changes of the physical and chemical surface properties.
In vitro testing revealed that surfaces with low amounts of EPA were nontoxic to MC3T3-E1 cells. The attachment and proliferation of MC3T3-E1 cells on surfaces with a chemically bound layer of EPA without preceding UV irradiation were increased compared to autoclaved Ti, differentiation of the cells was found to be slightly enhanced on the mRNA level, but a chemically bound layer of EPA did not enhance mineralization as measured by the Ca2+ content compared to Ti controls. The attachment and proliferation of S. epidermidis was decreased for surfaces with chemically bound EPA. In vivo, bone-to-implant attachment and mineral density of bone adjacent to EPA coated surfaces were reduced although the formation of new bone was maintained. Thus, surface coating of smooth Ti with EPA and using UV irradiation could be applicable for temporary bone fixation devices.