Clarifying the influence of albumin on the initial stages of magnesium corrosion in Hank's balanced salt solution

The corrosion behavior of Mg, a promising biodegradable metallic material, in protein-containing pseudophysiological environment is still not fully understood. In this work, the influence of albumin on the corrosion behavior of commercially pure magnesium (CP Mg) is investigated during short-term tests in Hank's Balanced Salt Solution (HBSS). This work focuses on the reactions at the Mg/medium interface from the perspective of the interactions among albumin, media components and substrate. Hydrogen evolution tests demonstrate that the physiological amount of albumin (40 g L−1) accelerates Mg corrosion in HBSS during the first few hours but slows down the degradation afterwards. The presence of albumin decreases the concentration of free Ca2+ in HBSS and delays formation of protective co-precipitation products on Mg surface. The evolution of local pH (differs from typically monitored bulk pH) near Mg/medium interface in albumin-containing HBSS is reported for the first time. Comparison of local and bulk pH values elucidates the pH buffering effect of albumin during the immersion period. Based on these results, adsorption, chelating and pH buffering effects are summarized as three important aspects of albumin influence on Mg corrosion. Additionally, constant replenishment of medium components is shown to be an influential factor during the Mg corrosion tests.