Low-Cost Hydroxyapatite Powders from Tilapia Fish

Synthetic hydroxyapatite {HAp, Ca 10 (PO 4 ) 6 (OH) 2 } is a bioactive and biocompatible material widely used in healthcare for bone implants and grafts, due to its chemical and structural similarity with biological hydroxyapatite present in bone tissues. In this work, HAp was processed by calcination of tilapia fish bones from fish reared in net tanks and slaughtered at the age of 360 days. The bones were cleaned and dried, calcined at 900°C for 8 h and submitted to high energy milling for 8 h, to produce HAp powder. The thermogravimetric analysis and differential thermal analysis (TGA-DTA), dynamic light scattering (DLS), x-ray diffraction (XRD), Rietveld refinement, Fourier-transform infrared spectroscopy (FTIR) with attenuated total reflection (ATR), Raman spectroscopy and scanning electron microscopy (SEM), were techniques used to characterize the material produced. The results indicate that the methodology employed is effective for the production of nanostructured HAp powder, with particle size ranging from 600 nm to 1200 nm and grain size between 0.25 and 1.1 µm (evaluated by SEM in one piece of calcined bone). TGA-DTA analysis indicates complete removal of organic components at temperatures above 600°C. XRD analysis and refinement by the Rietveld method indicated the presence of a single crystalline phase, HAp, with a Ca/P ratio of 1.66. The results obtained by Raman spectroscopy and FTIR-ATR show the presence of characteristic vibrational bands of HAp. In conclusion, the results of this work showed that the methodology used allowed the production of a natural and crystalline hydroxyapatite, with a Ca/P molar ratio of 1.66, with potential for use in bone reconstruction.