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

The factors that influence magnesium (Mg) corrosion in vitro are systematically evaluated from a review of the relevant literature. We analysed the influence of the following factors on Mg biocorrosion in vitro: (i) inorganic ions, including both anions and cations, (ii) organic components such as proteins, amino acids and vitamins, and (iii) experimental parameters such as temperature, pH, buffer system and flow rate. Considerations and recommendations towards a standardised approach to in vitro biocorrosion testing are given. Several potential simulated body fluids are recommended. Implementing a standardised approach to experimental parameters has the potential to significantly reduce variability between in vitro biocorrosion tests, and to help build towards a methodology that accurately and consistently mimics in vivo corrosion. However, there are also knowledge gaps with regard to how best to characterise the in vivo environment and corrosion mechanism. The assumption that blood plasma is the correct bodily fluid upon which to base in vitro methodologies is examined, and factors that influence the corrosion mechanism in vivo, such as specimen encapsulation, bear consideration for further studies.