Hydroxyapatite synthesis from a starfish and β-tricalcium phosphate using a hydrothermal method

Abstract

Hydroxyapatite HAp, Ca₁₀(PO₄)₆(OH)₂, was successfully synthesized using a hydrothermal method using β-tricalcium phosphate (β-TCP) and CaO from the starfish Mellita eduardobarrosoi sp. nov. The goal of this research was to synthesize a material with better characteristics, such as a high proportion of the HAp phase, homogeneous dimensions, and a good Ca/P ratio. To get it, different temperatures, concentration ratios and reaction times were tested. Synthesized HAp materials were characterized by Scanning Electron Microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). XRD showed that the proportion of the HAp phase tends to increase as the temperature and reaction times grow, which is corroborated by SEM characterization, where homogeneous in size HAp fibers were identified. Absorption bands related to the functional groups PO₄ and OH, as well as the characteristics of HAp, were found by FTIR. From the results obtained, optimal HAp is achieved at a temperature of 250 °C and a reaction time of 48 hours, producing a greater proportion of fibers with very homogeneous lengths and thicknesses, a Ca/P ratio of 1.65 (near stoichiometric), a higher crystalline degree, and a ratio of 3 : 1 of β-TCP and CaO.