2007 Volume 21 Pages 9-15
The effects of ionic surfactants, dodecyltrimethylammonium chloride (DTMAC) and sodium dodecyl sulfate (SDS), on the adsorption amount of bovine serum albumin (BSA) onto the surface of hydroxyapatite (HAP) were studied. BSA was bound to HAP owing mainly to electrostatic interaction between opposite charges on HAP and BSA in the absence of an additive. The adsorption amount of BSA on HAP increased with a concentration of added DTMAC by virtue of hydrophobic interaction between hydrocarbon chains of DTMAC bound to BSA and those adsorbed on HAP in the range of a low concentration of DTMAC. The adsorption amount, however, decreased with the concentration in the region of a higher concentration of DTMAC. This is because the expansion/denaturation of BSA was caused after the binding of much amount of DTMAC, resulting in an increase in a molecular occupation area of BSA on the HAP surface. On the other hand, in the presence of SDS, the adsorption amount of BSA on HAP monotonously decreased with a concentration of SDS owing to the strong effect of SDS on the expansion and concomitant denaturation of BSA.
