Zinc is one of the most promising biodegradable metal, which is able to degrade under physiological conditions at a sufficient rate. However, some factors are restricting their usability in the human organism for now. These restrictions are especially mechanical properties and insufficient interaction with the surrounding tissue. Despite the biodegradation, the interaction between cells and the material should be enhanced to avoiding its failure. Based on that, zinc properties are often modified by compounds regularly occurring in the human body to reach optimal performance of those materials. Until now, hydroxyapatite was commonly used for the preparation of permanent composites or the formation of the layers enhancing the interaction with the tissue. Unfortunately, these materials seem to be inappropriate for biodegradable materials due to their stability. It suggests that less stable apatites should be considered a better alternative to hydroxyapatite for biodegradable applications.

In this study, we prepared zinc-based composites with the content of two different ceramic reinforcements (hydroxyapatite, monetite). Besides, the different morphology of the particles was used to characterize their influence on mechanical properties. Monetite and hydroxyapatite possess similar values of strengths suggesting the mechanical properties were not influenced by slightly different composition. Further, the willingness of the nanoparticles to form conglomerates was observed in both cases. The process led to the formation of conglomerates in the material structure and significantly affected other material properties. The most interesting is the lower stability of the monetite under the simulated body conditions (pH > 7). During the zinc degradation, the oxygen depolarization reaction takes place. This process increases the pH value and leading to a dissolution of the monetite. The reproducibility of this process in the human body is strongly questionable due to several reasons and needs to be confirmed by long-term tests or by in vivo testing.