The current gold standard material for orthopedic applications is titanium (Ti), however, other materials such as cobalt-chromium-molybdenum (CoCrMo) are often preferred due to their wear resistance and mechanical strength. This study investigates if the bioactivity of CoCrMo can be enhanced by coating the surface with titanium oxide (TiO 2 ) by atmospheric pressure chemical vapor deposition (CVD), thereby replicating the surface oxide layer found on Ti. CoCrMo, TiO 2 -coated CoCrMo (CCMT) and Ti substrates were used for this study. Cellular f-actin distribution was shown to be noticeably different between cells on CCMT and CoCrMo after 24 h in osteogenic culture, with cells on CCMT exhibiting greater spread with developed protrusions. Osteogenic differentiation was shown to be enhanced on CCMT compared to CoCrMo, with increased calcium ion content per cell (p < 0.05), greater hydroxyapatite nodule formation (p < 0.05) and reduced type I collagen deposition per cell (p < 0.05). The expression of the focal adhesion protein vinculin was shown to be marginally greater on CCMT compared to CoCrMo, whereas AFM results indicated that CCMT required more force to remove a single cell from the substrate surface compared to CoCrMo (p < 0.0001). These data suggest that CVD TiO 2 coatings may have the potential to increase the biocompatibility of CoCrMo implantable devices.
TiO 2 thin films are deposited by atmospheric pressure (AP)CVD of TiCl 4 and ethyl acetate on various substrates heated to 500 8C. The substrates investigated are four different grades of stainless steel (304, 304L, 316, and 316L), titanium metal, goldcoated titanium metal, and gold-coated stainless steel (316 grade). The TiO 2 films are analyzed by Raman spectroscopy (RS) to determine the percentage of anatase present. Predominantly anatase films are produced on all the substrates, demonstrating the versatility of this method. Scanning electron microscopy (SEM) images reveal a marked difference in particle size between regions of high anatase content and lower anatase content, indicative of a difference in growth rate between anatase and rutile particles. Selected samples are shown to be photocatalytically active by degradation of resazurin dye by UV light. The rate of degradation is significantly faster than on the self-cleaning Saint Gobain Bioclean TM .
UV photofunctionalization of TiO2 coated implant surfaces enhanced markers of cell adhesion. This may prove to be advantageous for orthopaedic implants by supporting the colonisation and adhesion of cells capable of facilitating in bone healing.
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