Serum albumin can influence magnesium alloy degradation in simulated blood plasma for cardiovascular stenting

Magnesium (Mg) alloys are promising materials for biodegradable cardiovascular stents due to their good biocompatibility and low thrombogenicity. Since dissolved Mg is unlikely to cause any adverse effects, magnesium materials become safe choice in humans. Herein, we report on the in vitro degradable properties of a new bioresorbable implant for conceivable cardiovascular stent application, namely AZ80 magnesium alloy. The degradation behavior in simulated blood plasma (SBP) without and with 5- 40 g/L bovine serum albumin (BSA) was assessed using open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The results show that degradation susceptibility of the alloy at any exposure period depends very much on the surrounding electrolyte composition. Additions of 10-20 g/L BSA doses in SBP fluid lead to decrease the susceptibility of the alloy degradation due to forming an integrated protective adsorbed layer on the surface. Plausible explanations were given for the stimulating effect induced by BSA at concentrations lower than 10 g/L or higher than 20 g/L. The synergistic influence of the negatively charged adsorbed albumin molecules at the physiological concentration (40 g/L) and Cl- ions in the contacting medium was also investigated. The electrochemical results are very consistent with SEM and EDX surface analyses, as well as the antibacterial efficiency of the alloy.