Femtosecond Laser Microstructuring and Bioactivation of Titanium Surfaces for Middle Ear Ossicular Replacement Prosthesis
World Congress on Medical Physics and Biomedical Engineering
7.-12. September
München
2009
Type: Konferenzbeitrag
Abstract
Introduction: While a variety of materials have been evaluated for replacement of human middle ear ossicles following inflammation, titanium and its alloys have shown excellent sound transmission properties and biocompatibility. However, cartilage thickness at the tympanic membrane interface deteriorates over time, while fibrous tissue formation may dislodge the titanium prosthesis. This study was performed to evaluate the effect of microstructures and biologically active nanolayers on titanium surfaces in contact with adjacent biological tissue. Materials and Methods: Titanium samples of 5mm diameter and 0,25mm thickness were structured by means of a Ti:Sapphire femtosecond laser operating at 970nm. The structures applied were lines of cross-sectional parabolic shape of 5μm (parallel), 5μm (cross-hatch) and 10μm width (parallel). The inter-groove distance between two maxima was twice the line width. Nanocoating was applied by means of chemical vapor deposition (CVD) in various layers: Polyethylene Glycol (PEG) only, PEG with RGD peptide sequence and PEG + RGD + Bone Matrix Protein (BMP)-7. Results: Lines smaller than 5μm were not feasible due to the natural irregularity of the basic material with pits and level changes of up to 2μm. Cell culture revealed that microstructures were able to generate oriented cell growth along structured lines. PEG did perform as “stealth” coating to avoid unspecific protein adsorption. Discussion: The results show that microstructures can be applied on titanium surfaces for human implantation with reproducible and constant shapes. Further studies will focus on relative promotion of chondrocyte compared to fibrocyte growth by various concentrations of BMP-7.