[Adsorption of chondroitin sulfate-A to the surface of titanium]

To elucidate the adsorption mechanism of CS-A to the surface of titanium, 5 ml solutions of the CS-A were reacted with 2 g of native and 2 g of calcium-treated titanium powder for 48 h at 37 degrees C. Residual CS-A was detected by the carbazole elaborate method. The results showed that no CS-A attached to native titanium. Comparatively, titanium treated with calcium produced a significant adsorption of CS-A. At concentration of 60 micrograms/ml, the adsorption of CA-A to calcium-treated titanium powder attained the maximum, 83 micrograms/g. Only EDTA can liberate the bound CS-A from titanium surface. These findings suggest that calcium ion is necessary for the adsorption of CS-A to titanium.