Hydroxyapatite (HA) is not easily degraded in the body, and currently this is still a huge challenge. In this study, we investigated (1) crystal-phase transformation of an electrode plate and (2) the addition of hydrogen peroxide as methods to improve biodegradation for cobalt-HA (CoHA). Results show that the addition of a high concentration of hydrogen peroxide will significantly reduce the crystallinity and particle size of CoHA. In addition, the biodegradability of CoHA was evaluated by immersion in phosphate-buffered saline. The pH value of PBS increased with an increasing H2O2 concentration and release of cobalt ions. Moreover, the pH value and the release curve of cobalt ions showed that the addition of hydrogen peroxide achieved better biodegradation than did a change in the crystal phase of the electrode plate. We confirmed that the addition of hydrogen peroxide can effectively improve CoHA's degradation behavior in simulated body fluid.
