title: Solubility of Mg-containing beta-tricalcium phosphate at 25 degrees C.
abstract: The equilibrium solubility of Mg-containing beta-tricalcium phosphate (betaMgTCP) with various magnesium contents was determined by immersing betaMgTCP powder for 27 months in a CH(3)COOH-CH(3)COONa buffer solution at 25 degrees C under a nitrogen gas atmosphere. The negative logarithm of the solubility product (pK(sp)) of betaMgTCP was expressed as pK(sp)=28.87432+1.40348C-0.3163C(2)+0.04218C(3)-0.00275C(4)+0.0000681659C(5), where C is the magnesium content in betaMgTCP (mol.%). The solubility of betaMgTCP decreased with increasing magnesium content owing to the increased structural stability and possible formation of a whitlockite-type phase on the surface. As a result, betaMgTCP with 10.1 mol.% magnesium had a lower solubility than that of hydroxyapatite below pH 6.0. betaMgTCP was found to be more soluble than zinc-containing beta-tricalcium phosphate given the same molar content of zinc or magnesium. The solubility of betaMgTCP and release rate of magnesium from betaMgTCP can be controlled by adjusting the Mg content by selecting the appropriate pK(sp).
authors.affiliation: Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-1 Higashi, Tsukuba-shi, Ibaraki 305-8566, Japan. lixia-ri@aist.go.jp
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Atsuo
authors.initials: A
authors.lastname: Ito
authors.forename: Yu
authors.initials: Y
authors.lastname: Sogo
authors.forename: Xiupeng
authors.initials: X
authors.lastname: Wang
authors.forename: R Z
authors.initials: RZ
authors.lastname: LeGeros
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002021:Buffers; D002130:Calcium Phosphates / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D015233:Models, Statistical; D011208:Powders; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002021:Buffers; D002130:Calcium Phosphates; D011208:Powders; C485817:beta-tricalcium phosphate; D017886:Durapatite; D008274:Magnesium; D015032:Zinc