Abstract
The effect of a cationic surfactant, dodecyltrimethylammonium chloride (DTMAC), on the adsorption of bovine serum albumin (BSA) to the surface of hydroxyapatite (HAP) was studied. BSA was bound to HAP owing mainly to electrostatic interaction between opposite charges on HAP and BSA in the absence of an additive. On the other hand, the adsorption amount of BSA by HAP decreased after attaining a maximum with a concentration of DTMAC when a concentration of BSA was kept constant at 0.2w/v%. At a low concentration region of DTMAC, the adsorption amount of BSA on HAP increased with the concentration by virtue of hydrophobic interaction between hydrophobic groups of DTMAC bound to BSA and those adsorbed on HAP. The adsorption amount, however, decreased with the concentration at a high concentration region of DTMAC. This is because the expansion/denaturation of BSA molecule was caused by the binding of much amount of DTMAC, resulting in an increase in a molecular occupied area of BSA.
