Degradation susceptibility of surgical magnesium alloy in artificial biological fluid containing albumin

Abstract

The objective of this study is to investigate the corrosion susceptibility of surgical AZ91 magnesium alloys in simulated body fluids (SBFs) consisting of bovine serum albumin (BSA) and acidic SBFs (pH 5) using electrochemical methods. The addition of BSA significantly moves the open-circuit potential toward a more positive value and suppresses the corrosion reaction. The corrosion resistance under the open-circuit conditions in the SBFs with 1 g/L BSA is approximately twice that in the SBFs. A higher BSA concentration decreases the corrosion susceptibility. In addition, the acidic SBF results in a higher alloy dissolution rate. The possible mechanisms are discussed.

Biodegradable magnesium alloys for orthopaedic applications: A review on corrosion, biocompatibility and surface modifications

“…29 that adsorption of bovine serum albumin (BSA) on AZ91 Mg alloy decreases the cathodic current and enhance the corrosion resistance in SBF [111]. It was observed that corrosion resistance increases with an increase in BSA concentration due to their blocking effect of the protein adsorbed layer which can suppresses the dissolution of AZ91 Mg alloys.…”

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

“…SEM analysis indicated C and N peaks, and appeared to indicate incorporation of proteins into the corrosion product layer [84]. The proposed mechanism was that the divalent Mg ions interacted with the proteins to form a covering layering, and thereby decreased the corrosion rate [83].…”

“…These studies have often focused on albumin as these are the most abundant protein species in blood plasma [80,81]. In general, proteins are incorporated into an in vitro system by the mixing of foetal bovine serum (FBS) or bovine serum albumin (BSA) into a SBF [82,83].…”

“…Liu et al [83] conducted an electrochemical study of AZ91 and found the addition of BSA decreased the open circuit potential (OCP) of the sample, but the addition of 1 g L −1 protein had minimal effect on the corrosion rate. A further study by Liu et al [81] on Mg-1.5Ca in NaCl solutions containing albumin found that the presence of proteins increased the charge transfer resistance of the corrosion layer on the surface of the Mg sample, and substantially decreased the corrosion rate as measured by hydrogen evolution.…”

“…However, this does not appear to be the case, as the protein concentrations presented in Table 5 suggest that E-MEM +FBS contained less than 10% of the proteins present in blood Plasma. In the initial study by Liu et al [83] proteins were added to a maximum of 1 g L −1 , again a small fraction of the levels present in blood plasma. In stark comparison, Walker et al [48] and Kirkland et al [72] incorporated 40 g L −1 of proteins, achieving close to physiological levels, and much higher corrosion rates than in vivo.…”