Synthesis of fluorapatite-hydroxyapatite nanoparticles and toxicity investigations

Abstract

In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatible and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering.

Keywords: biocompatibility; fluorapatite; hydroxyapatite; nanoparticles; sol-gel.

Figure 1

Powder preparation by sol-gel method.

Figure 2

Fourier transform infrared spectroscopy of the heat-treated powder at 550°C.

Figure 3

X-ray diffraction curves of powder after heat treatment at 550°C.

Figure 4

Particle size distribution of two-phase fluorapatite–hydroxyapatite powder at 550°C.

Figure 5

Scanning electron microscopy images of fluorapatite–hydroxyapatite nanoparticles (5A: 4000X; 5B:10,000X).

Figure 6

Transmission electron microscopy shows nanoparticles with regular shapes.

Figure 7

Optical microscopic images of cells cultured in the presence of control samples (sample (A) containing the powder (B)).