Synthesis of Rubidium-doped Calcium Hydroxyapatite Nanoparticles for Biomedical Applications

 Due to high biocompatibility, bioactivity, and natural occurrence in bones and teeth, synthetic calcium hydroxyapatite (CaHAp) is a widely applied biomaterial in tissue engineering, including orthopedic surgery and dentistry. However, the brittle nature and low strength reduce its durability, which can be improved by doping metal ions. Rubidium (Rb) is an essential trace element that works as an antibacterial agent in the human body; therefore, it can be doped in synthetic Ca-HAp to promote its durability. In this work, Rb-doped calcium hydroxyapatite (Rb-HAp) nanoparticles are synthesized by the coprecipitation method at low temperatures. Phase purity, crystallinity, doping level, and mechanical properties are investigated by X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and micro-hardness tester. It is observed that a minute quantity (≈ 0.02%) of Rb remained in the apatite structure when 5% of Rb+ is doped via in situ method. Moreover, small dopant concentration did not affect the crystal structure and the tensile strength of HAp.