In situ sol-gel derived Fluor-hydroxyapatite nanoparticles using calcium nitrate and triethyl phosphite precursors

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) has attracted much interest as an implant material for teeth and bones, due to the similarity of its crystallography and chemical composition to that of human hard tissues[1,2]. In most cases, the controlled solubility of HA is an important factor,since it induces bioactivity, osteoconductivity, and therapeutic effects. On the other hand, pure fluorapatite (FA, Ca10(PO4)6(F)2) is known to have a much lower solubility than HA, because FA possesses a greater stability than HA, both chemically and structurally [3-5]. Moreover, theFA forms fluor-hydroxyapatite (FHA, Ca10(PO4)6(OH,F)2) solid solutions with HA through the replacement of OH- by F-. Hence, modulation of the extent of fluoride substitution provides an effective way of controlling the solubility of the apatite. The synthesis of HA powder has been performing over the past few years, using different techniques, such as precipitation, hydrothermal, and sol-gel methods [6]. Among these, the sol-gel approach offers many advantages over other techniques