Biomedical potential of bovine-derived hydroxyapatite: synthesis strategies, characterization and applications

Hydroxyapatite (HAp), a calcium phosphate material that closely resembles the mineral phase of natural bone, is widely studied due to its biocompatibility, bioactivity, and osteoconductivity, making it an important biomaterial in biomedical applications. With increasing demand for HAp-based materials, considerable research has focused on developing synthesis methods to tailor its structural and functional properties. Variations in synthesis strategies can significantly influence crystallinity, particle size, porosity, and surface characteristics of HAp, which in turn affect biological performance. Among biogenic sources, bovine-derived HAp has received attention due to its compositional similarity to natural bone mineral. Several studies report that, depending on extraction and processing conditions, bovine HAp can exhibit favorable crystallinity, mechanical stability, and porous architecture; however, these properties remain highly dependent on preparation parameters and require careful control. This review summarizes the synthesis of bovine HAp using conventional methods (thermal decomposition and hydrothermal techniques), hybrid approaches (calcination combined with vibro-milling and alkaline heat treatment, as well as ultrasonic-assisted spray drying), and emerging techniques such as subcritical water processing, transferred arc plasma, and annealing, each offering varying degrees of control over physicochemical properties. Characterization techniques, including X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), and energy-dispersive X-ray spectroscopy (EDX), are discussed for evaluating crystallinity, morphology, and elemental composition respectively. Furthermore, the biomedical applications of bovine-derived HAp are reviewed, including bone tissue engineering, bone grafting, dental repair, drug delivery, bioactive coatings, and antibacterial activity. While bovine-derived HAp shows promise as a sustainable and multifunctional biomaterial, further studies are required to address challenges related to processing consistency, long-term performance, and clinical translation.