Tailoring Si-substitution level of Si-hydroxyapatite nanowires via regulating Si-content of calcium silicates as hydrothermal precursors

The silicon (Si) substituted hydroxyapatite [Ca10(PO4)6(OH)2, Si-HAp] nanowires with different Si-substitution levels were synthesized via a hydrothermal reaction of the different Si containing precursors of CaSiO3 (CS), Ca2SiO4 (C2S) and Ca3SiO5 (C3S) ceramic powders in trisodium phosphate (Na3PO4) aqueous solution, in the absence of any surfactants and organic solvents. The results showed that the morphology transformation trend of particle shaped CS to Si-HAp nanowires is stronger than that of C2S and C3S. After hydrothermal treatment of the precursors at 180 °C for 7 days, the particle shape precursors transformed into Si-HAp nanowires with a width of ~100 nm and length up to 3 μm. Moreover, the Si-substitution amount (0.318–3.75 wt%) of the Si-HAp nanowires could be facilely tailored by regulation of the Si-content of the precursors. Our study suggested that the hydrothermal transformation of the calcium silicate precursors with different Si-contents provides a facile approach to regulate the Si-substitution level of the Si-HAp nanowires, and the synthetic Si-HAp nanowires might be used as bioactive materials for hard tissue regeneration applications.