title: Solubility of strontium-substituted apatite by solid titration.
abstract: Solid titration was used to explore the solubility isotherms of partially (Srx-HAp, x=1, 5, 10, 40, 60 mol.%) and fully substituted strontium hydroxyapatite (Sr-HAp). Solubility increased with increasing strontium content. No phase other than strontium-substituted HAp, corresponding to the original titrant, was detected in the solid present at equilibrium; in particular, dicalcium hydrogen phosphate was not detected at low pH. The increase in solubility with strontium content is interpreted as a destabilization of the crystal structure by the larger strontium ion. Carbonated HAp was formed in simulated body fluid containing carbonate on seeding with Sr10-HAp, but the precipitate was strontium-substituted on seeding with Sr-HAp. Strontium-substituted HAp might be usable as a template for the growth of new bone, since nucleation appears to be facilitated.
authors.affiliation: Department of Orthopaedics & Traumatology, The University of Hong Kong, Kowloon, Hong Kong.
authors.forename: H B
authors.initials: HB
authors.lastname: Pan
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.forename: W M
authors.initials: WM
authors.lastname: Lam
authors.forename: J C
authors.initials: JC
authors.lastname: Wong
authors.forename: B W
authors.initials: BW
authors.lastname: Darvell
authors.forename: K D K
authors.initials: KD
authors.lastname: Luk
authors.forename: W W
authors.initials: WW
authors.lastname: Lu
mesh_terms: D001826:Body Fluids; D002118:Calcium / Q000737:chemistry; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013324:Strontium / Q000737:chemistry*; D013696:Temperature; D017186:Titrimetry / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D006882:Hydroxyapatites; D010710:Phosphates; C076185:strontium hydroxyapatite; D002118:Calcium; D013324:Strontium