Vibrational spectroscopic characterization of new calcium phosphate bioactive coatings

In this work calcium phosphate (CaP) compounds with different PO43-/HPO42- R molar ratios in the 0.65-149 range were synthesized. In fact, all these Caps contain different amounts of HPO42- and PO43- ions as well as the amorphous precursors (tricalcium phosphate and octacalcium phosphate) of hydroxyapatite deposition, which was shown by in vitro and in vivo measurements. Spectroscopical IR and Raman results showed the presence of bands whose intensity ratio can be related to the molar ratio R; in particular, the Raman I-962/I-987 and the IR I-1035/I-1125 intensity ratios were characterized as markers of the molar ratio. For these CaP compounds a nucleation model, which was based on the ability of HPO42- ions to form strong H bonds with PO43- ions, was proposed. (C) 2000 John Wiley & Sons, Inc.