Adsorption of bovine serum albumin on CoCrMo surface: Effect of temperature and protein concentration

The adsorption of bovine serum albumin (BSA) onto CoCrMo surface has been studied as a function of concentration of BSA and temperature by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) technique was used to investigate the interfacial behaviour of BSA at open circuit potential (OCP). The charge transfer resistance was very sensitive to the amount of adsorbed protein, indicating that the adsorption process was accompanied by the transfer of charge and influenced the mechanism and kinetics of the corrosion reaction. At all the temperatures studied, adsorption of BSA onto the CoCrMo surface was successfully described with a Langmuir adsorption isotherm. EIS study was also carried out for determine the surface charge density, resulting from protein adsorption, and it was shown to be directly proportional to the amount of adsorbed protein (surface concentration). Thermodynamic data of adsorption was obtained for analyzing the adsorption of BSA onto CoCrMo surface. Gibbs free energy of adsorption, ΔGADS values, for BSA in the investigated temperature range (−51 kJ mol−1) showed that the molecules have a strong affinity for the CoCrMo surface. Enthalpy (ΔHADS) and entropy (ΔSADS) of adsorption suggested that the adsorption process of BSA onto the CoCrMo surface is an endothermic process and the molecule suffers structural changes when adsorbing on the metallic surface.