Iron-Gold Composites for Biodegradable Implants: In Vitro Investigation on Biodegradation and Biomineralization

The biocompatibility and biodegradation of iron (Fe)make it asuitable candidate for developing biodegradable metallic implants.However, the degradation rate of Fe in a physiological environmentis extremely slow and needs to be enhanced to a rate compatible withtissue growth. Incorporating noble metals improves the Fe degradationrate by forming galvanic couples. This study incorporated gold (Au)into Fe at very low concentrations of 1.25 and 2.37 mu g/g toimprove the degradation rate. The electrochemical corrosion test ofthe samples revealed that the Au-containing samples showed a four-timeand nine-time faster degradation rate than pure Fe. Furthermore, theimmersion test and long-term electrochemical impedance spectroscopyconducted in simulated body fluid (SBF) revealed that the Au-incorporatedsamples exhibited increased bioactivity and degraded faster than pureFe. Integrating nanogold into a Fe matrix increased the in situ formationof hydroxyapatite on the sample's surface and did not causetoxicity to L929-murine fibroblast cells. It is suggested that Fe-Aucomposites with low concentrations of Au can be used to tailor thebiodegradation rate and promote the biomineralization of Fe-basedimplants in the physiological environment.