Papers by Author: Tae Sung Bae

Abstract: Carbon nanotubes (CNTs) have excellent chemical, physical, and biological properties such as strong cell adhesion, protein adsorption and cell proliferation in vitro. Excellent osteocompatibility for the CNT monolith was also reported in vivo. The purpose of this study was to evaluate the effects of anodized titanium coated with multiwalled CNTs (MWCNTs) on human osteosarcoma Saos2 cells and bone tissue. Saos2 cells on CNT-Ti showed excellent proliferation with extension of cell morphology in all directions. CNT-Ti wire was implanted in the bone marrow of femurs of rats. At 2 weeks after surgery, histological investigations revealed that bone tissue attached to the surface of the CNT-Ti directly. Thus the surface modification of anodized Ti by MWCNTs can be effective for bone formation.

Abstract: Magnesium has been proposed as an implant metal due to its low weight and inherent biocompatibility. However, it use as a biomaterial is seriously limited by its poor corrosion n resistance. Die-cast AZ91D and rolled AZ31B alloys, which are commercial magnesium alloys, were used in this study. After plasma anodization, SEM showed that the surface had a relatively high porosity with some micro-cracks. EDX revealed Mg, Al and Zn on the surface of the samples before anodization. After anodization , there was an increase in the oxygen EDX peak intensity with a concomitant decrease in the magnesium intensity . Anodized AZ91D had the best corrosion resistance according to the potentiodynamic polarization curves. After immersion in Hanks solution for 10 days, the untreated AZ31B sample had the highest pH value due to formation of OH- on the film surface.

Abstract: This study examined the effect of the current density, anodizing voltage and time on the surface characteristics of titanium during anodic spark oxidation. Anodic spark oxidation was performed at different concentrations of electrolyte composed of DL-α-glycerophosphate (DL-α-GP) and calcium acetate (CA). The specimens were anodized at various conditions (current density, anodizing voltage, and duration) in a fixed electrolyte concentration. Anodized specimens were treated hydrothermally under high pressure steam using an autoclave. Homogeneous anodic oxide films were produced by anodic spark oxidation on the titanium surface with 1~4 μm diameter pores, and the breakdown voltage was changed by the electrolyte concentration. After the hydrothermal treatment, hydroxyapatite crystals formed as an enlarged polygonal shape in the higher concentration of DL-a-GP group and as thin needles in higher concentration of CA group. The bioactivity and osteoblast growth was good for the anodized surface at 340V compared with the groups applied other parameters.