Abstract
The hydroxyapatite has been extensively investigated with respect to its potential for bone tissue engineering and removal of heavy metal ions from aqueous solutions. Fish scales are a natural source for calcium phosphate source though considered as wastes in daily life. In this study, hydroxyapatite was extracted and obtained from scales of Tilapia fish (Oreochromis mossambicus). The mineral was confirmed to be hydroxyapatite by X-ray diffraction and energy dispersive spectrometry. The hydroxyapatite powders obtained from fish scales was used as raw materials and scaffolds were synthesized by the freeze casting technique. The well aligned laminar structures with 10-80 μm channels was revealed by SEM, meanwhile, the pore size can be controlled by tuning cooling rates. It is able to synthesize scaffolds with microstructure mimicking cancellous bone, which exhibit good mechanical strength. The cell proliferation test was done by culturing human osteoblast cells within the scaffolds, and cell viability was evaluated by the MTS assay. Histological evaluation was carried out to characterize the cell ingrowth. Results confirmed that the scaffolds were not cytotoxic. Additionally, hydroxyapatite has good ability to remove heavy ions in water. We chose lead ion as indicator to test the sorption ability, and used isotherm models to describe the sorption behavior. From Atomic Absorption Spectrometer (AAS) analysis, the scaffolds eliminated 99% of lead ion in a short time, providing efficient capability of heavy metal ions removal. Inexpensive fish scales can be utilized to synthesize hydroxyapatite scaffolds by freeze casting and have great potential to be applied in various fields.