Accelerated corrosion of 316L stainless steel in simulated body fluids in the presence of H2O2 and albumin.

316L stainless steel has been widely used for orthopedic devices. Inflammatory response and direct contact with abundant proteins after implantation lead to corrosion issues of biomedical stainless steels. The effect of combination of H2O2 and albumin on the corrosion of 316L stainless steel has been investigated for the first time in simulated body fluids at 37 °C with electrochemical and long term immersion tests. ICP-MS measurement after 16 weeks immersion reveals that the total concentration in the presence of both species was substantially higher than physiological saline alone, and even higher than the sum of H2O2 alone and albumin alone. Electrochemical polarisation curves and electrochemical impendence spectra show that albumin accelerated anodic dissolution and suppressed cathodic reaction, while H2O2 promoted cathodic reaction. Also, H2O2 and/or albumin promoted meta-stable/stable pitting corrosion and decreased charge transfer resistance. Accelerated corrosion of 316L stainless steel in the presence of both species was attributed to the promoted formation of Fe oxides and CrOOH by H2O2 and the largely favoured dissolution of these oxides by the addition of albumin, significantly accelerating Fe and Cr release. The synergistic interaction between both species indicates significant underestimation of corrosion rate evaluated solely in physiological saline. These findings suggest the necessity of using more realistic solutions to evaluate corrosion resistance of biomedical alloys for future in-vitro studies.