Concurrent Binding of Calcium Ion and Chondroitin Sulfate Ion to the Surface of Hydroxyapatite

概要

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Concurrent adsorption of chondroitin sulfate ion (Chs) and calcium ion (Ca^<2+>) to hydroxyapatite (HAP) from an aqueous solution of Na_2Chs mixed with CaCl_2 was studied at 25℃. The adsorbed amount of Chs increased with increasing concentration of Ca^<2+> for the following two reasons : (a) Ca^<2+> adsorbed on the surface of HAP offers an adsorption site for Chs owing to its positive charges, and (2) the binding of Ca^<2+> to anionic sites of Chs depresses the inter- and intramolecular electrostatic repulsion between Chs segments, resulting in the dense adsorption of Chs. The apparent amount of Ca^<2+> adsorbed by HAP is also increased in the presence of Chs, because Ca^<2+> is captured by negative charges of Chs adsorbed on the surface of HAP as well as by adsorption sites for Ca^<2+> on the surface of HAP itself. However, it was concluded that the amount of Ca^<2+> adsorbed directly on the surface of HAP in the presence of Chs is almost the same as that in the absence of Chs when the adsorbed amount of Ca^<2+> is shown as a function of the concentration of free Ca^<2+>.
公益社団法人日本薬学会の論文
1984-10-25