Following Zn corrosion during long term immersion test in physiological solutions to establish the potential of zinc as biodegradable prosthetic material

Corrosion behaviour of commercially pure Zn during immersion up to 4 weeks is studied in three different solutions mimicking physiological environment, i.e. Hanks' Balance Salt Solution (HBSS), Dulbecco's modified Eagles' medium (DMEM) and DMEM with 10 % of fetal bovine serum (DMEM + 10 % FBS). Morphological characterizations, electrochemical tests, weight loss, and ion release measurements show that the corrosion mechanism is significantly affected by the physiological solution. In HBSS a phosphate-based conversion layer forms resulting to significantly slow down the corrosion rate, while in DMEM an intergranular corrosion occurs. The latter is hindered due to the presence of proteins from the fetal bovine serum in DMEM+FBS. The main cathodic process is oxygen reduction in all physiological media. Direct estimate of corrosion rate by gravimetric measurements revealed that zinc dissolution becomes very slow after two weeks of immersion in the employed physiological thus suggesting that zinc is not suitable for the fabrication of biodegradable implants in static fluidic condition.