Solvothermal synthesis of submillimeter ultralong hydroxyapatite nanowires using a calcium oleate precursor in a series of monohydroxy alcohols

Abstract Hydroxyapatite (Ca 10 (OH) 2 (PO 4 ) 6 , HAP), as the major inorganic component of bones and teeth in vertebrates, is a very important biomaterial with high biocompatibility, nontoxicity and high thermal stability, thus, it has wide applications in various biomedical fields. Among various morphologies of HAP, HAP nanowires are very promising for various applications; however, the synthesis of ultralong HAP nanowires with lengths larger than 100 μm is highly challengeable and has been rarely reported. In this paper, we report, for the first time, the solvothermal synthesis of submillimeter-sized ultralong hydroxyapatite nanowires using calcium oleate as the precursor and NaH 2 PO 4 as the phosphorus source in a series of monohydroxy alcohols. The products are characterized by scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared (FTIR) spectroscopy. The as-prepared ultralong hydroxyapatite nanowires have diameters of tens of nanometers and lengths from several hundred micrometers up to nearly one millimeter. This method is simple, surfactant-free, environment friendly, and generally applicable in a series of monohydroxy alcohols including methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol and 1-hexanol. Moreover, this method may be scaled up for large-scale production of ultralong hydroxyapatite nanowires. The as-prepared ultralong hydroxyapatite nanowires are promising for applications in various fields such as bone tissue engineering, drug delivery, adsorbent for organic pollutants and heavy metal ions, and nonflammable inorganic paper.