Surfactant-free solvothermal synthesis of hydroxyapatite nanowire/nanotube ordered arrays with biomimetic structures

Hydroxyapatite (HAp), as the main inorganic constituent in vertebrate bones, is an important biomaterial. However, fabricating biomimetic HAp ordered arrays of one-dimensional nanostructures remains a challenge. Herein, we report a solvothermal method for the preparation of HAp nanowire/nanotube ordered arrays with biomimetic structures using CaCl2 and NaH2PO4 center dot H2O in ternary solvents of water, ethylene glycol (EG) and N,N-dimethylformamide (DMF) without using any surfactant. The effects of the solvents on the morphology and crystal phase of the product as well as the formation mechanism of HAp nanowire/nanotube ordered arrays are investigated. This method does not need any hard template or surfactant, avoiding the procedures and cost for their removal in the product. The products are characterized with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetric analysis (DSC) and thermogravimetric analysis (TG). The cytotoxicity of the as-prepared HAp samples with different morphologies are also tested.