Self-dissolution assisted coating on magnesium metal for biodegradable bone fixation devices

An attempt was made to develop a self-dissolution assisted coating on a pure magnesium metal for potential bone fixation implants. Magnesium phosphate cement (MPC) was coated successfully on the magnesium metal in ammonium dihydrogen phosphate solution. The in vitro degradation behaviour of the MPC coated metal was evaluated using electrochemical techniques. The MPC coating increased the polarisation resistance (RP) of the metal by similar to 150% after 2 h immersion in simulated body fluid (SBF) and reduced the corrosion current density (i(corr)) by similar to 80%. The RP of the MPC coated metal remained relatively high even after 8 h immersion period. However, post-degradation analysis of the MPC coated metal revealed localized attack. Hence, the study suggests that MPC coating alone may not be beneficial, but this novel coating could provide additional protection if used as a precursor for other potential coatings such as biodegradable polymers or calcium phosphates.