Synthesis and Characterization of Natural HAp/β-TCP Biphasic Calcium Phosphate From Salmon Bone Using a Simplified, Low-Cost Technique

Bioceramics containing biphasic calcium phosphates (BCP) are the preferred material for various bone healing applications. BCP consists of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HAp) and offers a balance between solubility and resorption, which promotes cell interaction and tissue growth. There is high demand to synthesize BCP from natural sources using simple and inexpensive methods. This study investigated the effects of calcination temperature on the phase structure, chemical composition, and microstructure of BCP powders synthesized from raw salmon bone (Atlantic salmon) using a simplified, low-cost technique. The successful synthesis of BCP powder from raw salmon bone was confirmed using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The physical and chemical characteristics were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). XRD results revealed the coexistence of HAp and β-TCP phases at calcination temperatures above 600°C for 2 h, indicating the formation of BCP compounds. The relative phase content of HAp and β-TCP changed when the calcination temperature increased from 600 to 1000°C. The crystallite size of HAp and β-TCP increased while the lattice strain decreased as the calcination temperature increased. All samples showed polyhedral lumps of irregular sizes, and the Ca/P ratio decreased from 2.14 to 1.95 with higher calcination temperatures. The FTIR results of all samples revealed the existence of the functional groups of phosphate (PO₄^3-) hydroxyl (OH^-) and carbonate (CO₃^2-), which are characteristic of the BCP structure. The optimal phase ratio of HAp/β-TCP at approximately 60:40 was obtained by the samples at a calcination temperature of 800°C. This study reports on a new simplified, low-cost technique to synthesize BCP powder from salmon bone.