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 the presence of calcium and phosphate ions. Isotherm data have shown that the adsorption process does not follow the Langmuir model (inflection points). The maximum adsorption (Admax) at pH 6.8 is 1.13 +/- 0.21 mg m-2. For the pH dependence of adsorption the amount adsorbed increases with decreasing pH (at pH 5.15 Admax = 1.31 +/- 0.2 mg m-2), indicating that hydration effects are important. Adsorption increases and decreases in the presence of calcium (at pH 6.8 for 0.002 M Admax = 1.73 +/- 0.23 mg m-2) and phosphate (at pH 6.8 for 0.002 M Admax = 0.64 +/- 0.14 mgm-2)ions, respectively, indicating that electrostatic effects are important. The time dependence, isotherm and desorption data provide indirect evidence of possible conformational changes in the BSA molecule.