Magnesium whitlockite (Ca18Mg2H2(PO4)14) is the second most abundant mineral in human body and one of the main components of the human hard tissue, constituting to approximately 20–35 wt% [1]. This compound is known for its excellent biocompatibility and osteogenic capability which makes this material a promising candidate for application in bone regeneration [2]. However, synthesis of pure phase whitlockite remains a challenge due to poor thermal stability, high sensitivity to synthesis conditions and large amount of possible intermediate phases.
Incorporation of biologically active ions into the structure of the material can result in superior biological performance of calcium phosphate based materials in addition to expanded clinical applications of the material. To further improve biological properties of whitlockite, as well as design new properties for specific medical fields, other ions instead of Mg could be used for synthesis of the compound. Zn substituted calcium phosphates are characterized by enhanced rate of metabolic processes and antibacterial properties which makes these materials very attractive for usage in medicine [3].
The main goal of the present work was to develop a hydrothermal synthesis method to obtain pure phase and low crystallinity whitlockite powders containing Zn ions. For this purpose synthesis conditions such as temperature, time, pH, concentration and Ca/Zn molar ratio in the initial solution were carefully studied and optimized. Calcium hydrogen phosphate dihydrate and zinc acetate dihydrate were used as starting materials. Synthesized compounds were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES) and Raman spectroscopy.