ADSORPTION OF BOVINE SERUM-ALBUMIN ONTO SYNTHETIC CALCIUM HYDROXYAPATITE - INFLUENCE OF PARTICLE TEXTURE

Calcium hydroxyapatites (CaHAPs), with particle lengths varying from 27 to 103 nm but similar widths of about 15 nm, were synthesized, and the adsorption behavior of bovine serum albumin (BSA) on these synthetic CaHAPs was investigated at pH 6.0 and 15 degrees C. The size of the synthetic CaHAP particles increased on increasing the concentration of H3PO4 in the aging solution. The adsorption isotherms of BSA on CaHAPs were pseudo-langmuir type. The saturated amounts of adsorbed BSA (n(s)), which an the plateau values of the adsorption isotherms, increased with an increase in particle length of the CaHAPs. However, no relationship was found between n(s) and the molar ratio of calcium to phosphorus in CaHAP particles. These results suggest that the particle texture is significant in the adsorption of BSA. The large rod-like particles with flat surfaces are advantageous for the adsorption of negatively charged BSA by the large number of positively charged adsorption sites on the exposed ac or bc crystal faces.