Evaluation of electronic property and Volta potential distribution of CoCrMo alloy in presence of protein molecule by SKPFM and electrochemical measurements

In this research, the adsorption evaluation of bovine serum Albumin (BSA) proteins in the phosphate buffered solution on semiconductor character of the passive film on CoCrMo alloy was studied by means of scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), scanning Kelvin probe force microscopy (SKPFM), and electrochemical measurements. In the entire concentrations of BSA from 0 to 2 g.L-1, the lower corrosion potential and more passivity regions were detected. The potentiodynamic polarization and electrochemical impedance spectroscopy analyses results indicate that the lower concentration of BSA than 0.5 g.L-1 provide the higher corrosion current density and lower the charge transfer resistance. Likewise, the higher concentration of BSA than 0.5 g.L-1 have considerably effect on increasing the corrosion resistance on passive film. It is because that the BSA molecules strongly adsorbs passive film by electrostatic or hydrophobicity (chemisorption through carboxylate/amino group) interactions and then inhibits the electrochemical reactions. Mott-Schottky analysis demonstrated that the BSA protein in the high concentrations has a positive effect on reducing the density of defects including n-type or p-type semiconductor characters and space charge regions on passive film. AFM and SKPFM mappings visualized the presence of BSA protein adsorption on passive film with different topography and Volta potential distribution respect to the matrix.