THE INFLUENCE OF BETA-LACTOGLOBULIN ON THE GROWTH AND DISSOLUTION KINETICS OF HYDROXYAPATITE

The growth rate of hydroxyapatite (HAP) crystallites has been studied at pH 7.4, using the dual constant composition method. Addition of bet a-lactoglobulin (beta-Lg) at concentrations greater than about 2 p.p.m . reduces the growth rate, and the degree of inhibition increases with additive concentration, up to a value of about 100 p.p.m. Above this level, however, there is no further decrease in the rate, suggesting a limiting adsorption of beta-Lg at the HAP surface. beta-Lg also reduc es the constant composition dissolution rate of HAP, almost completely inhibiting the reaction after only 25% dissolution at a concentration of 800 p.p.m. In the absence of the additive the dissolution stops af ter 60% reaction.