Corrosion behavior of titanium in the presence of calcium phosphate and serum proteins.

The effect of calcium phosphate surface deposit and the surface adsorption of the serum proteins, bovine serum albumin (BSA) and fibrinogen, on the corrosion resistance and electrochemical behavior of (cp)titanium in phosphate buffer saline solution (pH 7.4) was investigated at physiological temperature, 37 degrees C, using electrochemical impedance spectroscopy and dc electrochemical polarization techniques. The formation of calcium phosphate deposit on the Ti surface decreased both the corrosion rate at the open circuit potential (OCP) and the anodic reaction current in the high anodic potential range (>2.6 V). Addition of BSA significantly moved the OCP towards a more negative (cathodic) potential and inhibited the cathodic corrosion reaction, but did not significantly change the corrosion resistance at the OCP. Addition of fibrinogen showed a similar, but less pronounced effect than BSA. The possible mechanisms leading to these observed effects are discussed.