Effect of trace elements on the sintering effect of fish scale derived hydroxyapatite and its bioactivity

Synthesis of nano-crystalline hydroxyapatite (HAp) from fish scale (Catla calla) was carried out by calcining of raw fish scale between 200 degrees C and 1200 degrees C. The synthesized powders were characterized using thermogravimetry differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The crystallinity, crystallite size, strain and cell parameters of fish scale derived calcined powders and chemically synthesized HAp (S-HAp) powders were estimated from XRD data. The average crystallite size of fish scale derived HAp powder increased with increasing calcination temperature. The fish scale derived HAp (FSH800) and S-HAp, calcined at 800 degrees C, showed crystallite size of 30 nm and 60 nm, respectively. ICP-AES analysis revealed that the fish scale derived HAp powder calcined at 1200 degrees C (FSH1200) contain significantly high amount of magnesium and strontium ions compared to S-HAp. After sintering at 1200 degrees C for 1 h, the relative density of FSH1200 was 20% higher than that of S-HAp due to better sinterability as a result of its small crystallite size and the presence of trace elements. In vitro cytotoxicity studies performed using human osteoblast-like cells (MG63) and mouse osteoblast cell line (MC3T3-E1) demonstrated that fish scale derived HAp (FSH1200) is non-toxic.