Elucidation of surface properties of calcium-ion-implanted titanium in biological systems

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Microdissolution of calcium ions from calcium-ion-implanted titanium into nitric acid solutions (pH -0.99,0,1, and 2) and phosphate-citric acid buffers (pH 5.2 and 7.2) at 310 K for 10^3-5x10^6s was characterized using X-ray photoelectron spectroscopy and Auger electron spectroscopy. As a result, the surface oxides with calcium were found to dissolve in the solutions. Oxygen decreased and titanium increased in the surface oxide according to the dissolution. In addition, hydroxyl radicals decreased in number and the proportion of Ti^<4+> in titanium increased. Core-level binding energies of calcium, and titanium originating from Ti^<4+> decreased with the dissolution. These changes were caused by the transformation of surface oxide according to the dissolution. That is, calcium dissolved and, consequently, the surface oxide became titanium oxide. The surface-modified layr consisted of three layrs while calcium existed in whole depth of the surface-modified layr. The calcium ions eluted … More into both solutions by the dissolution of the surface-modified layr itself and the dissolution of calcium by the diffusion through the surface-modified layr.13EA02 : In addition, to compare the surface properties of calcium-ion (Ca^<2+>)-implanted titanium with those of titanium and to investigate the mechanism of bone conductivity of Ca^<2+>-implanted titanium, amounts of hydroxyl radical of Ca^<2+>-implanted titanium and titanium were estimated. Also, the point of zero charge of oxide constituting surface oxides of Ca^<2+>-implanted titanium and titanium were determined. Results showed that the amount of active hydroxyl radical on Ca^<2+>-implanted titanium was found to be significantly larger than that on titanium, indicating that the number of electric-charging sites of Ca^<2+>-implanted titanium in electrolyte is more than that of titanium. The pzc values of rutile (TiO_2), anatase (TiO_2), and perovskite (CaTiO_3), were estimated to be 4.6,5.9, and 8.1, respectively. Thus, Ca^<2+>-implanted titanium surface is charged more positively in bioliquid than titanium, accelerating the adsorption of phosphate ions. Less