Characterization of very young mineral phases of bone by solid state 31phosphorus magic angle sample spinning nuclear magnetic resonance and X-ray diffraction.
The properties of bone mineral change with age and maturation. Several investigators have suggested the presence of an initial or "precursor" calcium phosphate phase to help explain these differences. We have used solid state 31P magic angle sample spinning (MASS) nuclear magnetic resonance (NMR) and X-ray radial distribution function (RDF) analyses to characterize 11- and 17-day-old embryonic chick bone and fractions obtained from them by density fractionation. Density fractionation provides samples of bone containing Ca-P solid-phase deposits even younger and more homogeneous with respect to the age of mineral than the calcium phosphate (Ca-P) deposits in the whole bone samples. The analytical techniques yield no evidence for any distinct phase other than the poorly crystalline hydroxyapatite phase characteristic of mature bone mineral. In particular, there is no detectable crystalline brushite [DCPD, CaHPO4 2H2O less than 1%] or amorphous calcium phosphate (less than 8-10%) in the most recently formed bone mineral. A sizeable portion of the phosphate groups exist as HPO4(2-) in a brushite (DCPD)-like configuration. These acid phosphate moieties are apparently incorporated into the apatitic lattice. The most likely site for the brushite-like configuration is probably on the surface of the crystals.
Roberts
J E
JE
Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge 02139.
Bonar
L C
LC
Griffin
R G
RG
Glimcher
M J
MJ
D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000737:chemistry / Q000196:embryology*; D002130:Calcium Phosphates / Q000032:analysis*; D005591:Chemical Fractionation; D002642:Chick Embryo; D009682:Magnetic Resonance Spectroscopy; D014961:X-Ray Diffraction
D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous; C494366:calcium phosphate, dibasic, dihydrate