One subclass of ceramic biomaterials is calcium phosphates (CPs). These minerals are found in biological tissues, where they form the main component of bones and teeth. CPs exhibit excellent biological properties, promote osteogenesis, and have a chemical composition and structure similar to the inorganic part of natural bone. Magnesium whitlockite (Mg-WH, \(Ca_{18}Mg_{2}(HPO_{4})_{2}(PO_{4})_{12})\) is a CP in which calcium is partially replaced by magnesium, and it also occurs in biological tissues. Compared to widely used clinical materials such as hydroxyapatite \((Ca_{10}(PO_{4})_{6}(OH)_{2})\) or tricalcium phosphate \((Ca_{3}(PO_{4})_{2})\), Mg-WH stands out for its higher corrosion resistance, plays a crucial role in bone defect healing, and promotes osteogenic differentiation. The use of synthetic Mg-WH in medicine is limited, primarily due to challenges associated with its synthesis. The excellent biological properties of synthetic Mg-WH, along with the ability to control its synthesis process, enable the development of materials with optimized mechanical, chemical, and biological properties, making Mg-WH a promising alternative to traditional biomaterials. Amorphous calcium phosphate (ACP), which has a non-crystalline structure and is therefore highly reactive, is an important member of the CP family and can serve as a precursor for synthesizing other phosphate-based materials, such as Mg-WH. In this study, Mg-WH was synthesized using ACP as a precursor. In a medium composed of a mixture of \((NH_{4})H_{2}PO_{4}\), \((NH_{4})_{2}HPO_{4}\), and \(Mg(CH_{3}COO)_{2}\) solutions (pH = 5.98), ACP dissolves, eventually leading to the precipitation of Mg-WH. The study examines the effects of various synthesis parameters, such as reaction duration, Mg ion concentration, and medium composition, on the composition of the synthesized products. The crystallinity, phase purity, and morphology of the synthesized samples were evaluated using XRD, FTIR, and SEM.
LOW-TEMPERATURE SYNTHESIS OF MAGNESIUM WHITLOCKITE FROM AMORPHOUS CALCIUM PHOSPHATE
Gabriele Egle Budzyte1, Greta Linkaite1, Aleksej Zarkov1, Aivaras Kareiva1, Inga Grigoraviciute1
1 Institute of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania