Effects of tantalum ion implantation on the corrosion behavior of AZ31 magnesium alloys

Osteo-odonto keratoprosthesis is one of the most successful forms of keratoprosthesis surgery for end-stage corneal and ocular surface disease. There is a lack of detailed comparison studies on the biocompatibilities of different materials used in keratoprosthesis. The aim of this investigation was to compare synthetic bioinert materials used for keratoprosthesis surgery with hydroxyapatite (HA) as a reference. METHODS: Test materials were sintered titanium oxide (TiO(2)), aluminum oxide (Al(2)O(3)), and yttria-stabilized zirconia (YSZ) with density >95%. Bacterial adhesion on the substrates was evaluated using scanning electron microscopy and the spread plate method. Surface properties of the implant discs were scanned using optical microscopy. Human keratocyte attachment and proliferation rates were assessed by cell counting and MTT assay at different time points. Morphologic analysis and immunoblotting were used to evaluate focal adhesion formation, whereas cell adhesion force was measured with a multimode atomic force microscope. RESULTS: The authors found that bacterial adhesion on the TiO(2), Al(2)O(3), and YSZ surfaces were lower than that on HA substrates. TiO(2) significantly promoted keratocyte proliferation and viability compared with HA, Al(2)O(3,) and YSZ. Immunofluorescent imaging analyses, immunoblotting, and atomic force microscope measurement revealed that TiO(2) surfaces enhanced cell spreading and cell adhesion compared with HA and Al(2)O(3). CONCLUSIONS: TiO(2) is the most suitable replacement candidate for use as skirt material because it enhanced cell functions and reduced bacterial adhesion. This would, in turn, enhance tissue integration and reduce device failure rates during keratoprosthesis surgery.

Comparison of candidate materials for a synthetic osteo-odonto keratoprosthesis device.

Surface analysis and oxidation behavior of Y-ion implanted AZ31 magnesium alloys

In order to investigate the effect of lanthanum ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted with lanthanum ions at a dose ranging from 1×1016 to 1×1017 ions/cm2 at maximum 130 °C, using a metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40 kV. The valence of the surface layer was analyzed by X-ray photoemission spectroscopy (XPS). Three-sweep potentiodynamic polarization measurement was employed to determine the aqueous corrosion resistance of zirconium in a 1 N H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion behavior of zirconium implanted with lanthanum ions compared with that of the as-received zirconium. Finally, the mechanism of improvement in the corrosion resistance of the lanthanum-implanted zirconium is discussed.

An Jin

Papers

Effect of yttrium ion implantation on aqueous corrosion resistance of zircaloy-4