Preparation and characterization of Mg(II) doped hydroxyapatite biocomposites

Bone tissue is a calcified matrix formed mainly by hydroxyapatite (HAp). Given the chemical similarity of HAp with several phosphate salts, researchers have been using them to develop clinical scaffolds for bone repair applications. Calcium polyphosphate (CPP) is an inorganic matrix, which presents biocompatibility and low toxicity, however it is brittle, requiring their association with polymers, such as alginate, to improve their mechanical properties. Furthermore, Mg2+ ions are present in the biological medium, participating in acid-base processes that modulate bone calcification and decalcification. Thus, incorporating Mg2+ ions and alginate in HAp could improve its bioactivity. In this context, this work presents the development of composite materials based on calcium polyphosphate, alginate, and magnesium, as candidates for bone tissue applications, using a simple and practical method, with low temperature. The preparation of the composites was achieved by precipitation of CPP in an aqueous medium containing the pre-solubilized alginate, followed by the addition of Mg2+. The materials were characterized by Raman and infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and dispersive energy spectroscopy. The results confirmed the formation of the desired composites with the hydroxyapatite structure, and with the potential to be evaluated for bone repair applications.