Synthesis and characterization of hydroxyapatite nano-rods from oyster shell with exogenous surfactants

Highlights: • The HA nano-rods were firstly synthesized utilizing surfactants with oyster shells by hydrothermal synthesis method. • The synthesis speed of HA nano-rods were faster than CK group when surfactants existed. • The HA nano-rods were no appreciable toxicity and may be a promising bone tissue engineering material. • The possible hard-template transformation mechanism from calcite and aragonite phases into HA phase was illustrated. -- Abstract: The Hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) has attracted widely research interests in many aspects, especially in repairing and replacing human hard tissues due to its brilliant biocompatibility, biological activity and so on. In the present article, HA nano-rods were rapidly developed via hydrothermal reaction synthesized with two representative surfactants (hexadecyltrimethylammonium bromide and sodium dodecyl sulfate) taken oyster shells as raw materials. The scanning electron microscopy (SEM) observations demonstrated that the micromorphology of synthesized HA was constructed of relatively regular nano-rods. From the zeta potential (ZP) analysis, the zeta potential of the developed HA was affected by different surfactants, which demonstrated the opposite potential value. The Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) results showed the HA phase was successfully and rapidly developed on the surface of oyster shell with the help of surfactants. The bio-safety of HA nano-rods was confirmed by MTT cytotoxicity assay using pre-osteoblasts cells. A possible hard-template transformation mechanism from the calcite and aragonite phases into the HA phase was proposed.