Impact of morphology-influencing factors in lecithin-based hydroxyapatite precipitation

Abstract Lecithin-based hydroxyapatite (HAp-LE) precipitation allows synthesis of biocompatible nanosized particles. In our previous paper regarding this process, we concluded that the concentration of lecithin gives control over the size and morphology of such particles. In this paper, a special emphasis is put on the analysis of initial pH value and reaction temperature to optimize lecithin-based synthesis conditions of the uniform spherical nanoparticles. We obtained HAp-LE in the presence of lecithin with reagent's initial pH value: 8, 9, 10 and in the reaction temperature range 24–80 °C to assess the influence of selected factors on morphology in HAp-LE precipitation process. According to scanning electron microscopy and nanoparticle tracking analysis, a pH of 10 and any synthesis temperature results in the spherical HAp-LE particles with the size around 100 nm. What is more, Fourier-transform infrared spectroscopy results indicate B-type hydroxyapatite in the precipitate. According to X-ray diffraction, mostly hydroxyapatite was obtained, but it differed in samples crystallinity because of the initial pH of synthesis. The results show that to obtain homogeneous, spherical particles, a lecithin-based synthesis should be conducted at pH 10 at any synthesis temperature.