ADSORPTION OF BOVINE SERUM-ALBUMIN ON TO TITANIUM POWDER

The adsorption of bovine serum albumin (BSA) on to titanium powder has been studied as a function of protein concentration and pH, and in th e presence of calcium and phosphate ions. Isotherm data have shown tha t the adsorption process does not follow the Langmuir model (inflectio n points). The maximum adsorption (Ad(max)) at pH 5.8 is 1.13 +/- 0.21 mg m(-2). For the pH dependence of adsorption the amount adsorbed inc reases with decreasing pH (at pH 5.15 Ad(max) = 1.31 +/- 0.2 mg m(-2)) , indicating that hydration effects are important. Adsorption increase s and decreases in the presence of calcium (at pH 6.8 for 0.002 M Ad(m ax) = 1.73 +/- 0.23 mg m(-2)) and phosphate (at pH 6.8 for 0.002 M Ad( max) = 0.64 +/- 0.14 mgm-2) ions, respectively, indicating that electr ostatic effects are important. The time dependence, isotherm and desor ption data provide indirect evidence of possible conformational change s in the BSA molecule.