Mössbauer spectroscopy and perturbed angular correlation studies of the rare-and alkaline-earth bone uptake

Emission Mössbauer spectra and Perturbed Angular Correlation measurements have been performed on samples of mineral bone powder labelled with 161Tb3+ or 133Ba2+ ions after either in vitro absorption or uptake by metabolic pathway. The study of these hyperfine spectra, compared with those carried out when 161Tb or 133Ba are situated in either hydroxyde lattice or phosphate one, shows that the uptake modes of rare-and alkaline-earth ions on the bone matrix are different. The rare earth ion seems to be absorbed on the surface bone in an environment of hydroxyl groups similar to the structure of a rare earth hydroxyde. The alkaline earth ion bone uptake appears more complicated and would make according to the following process : at first, surface absorption on the hydroxylapatite in a hydroxyde environment and then cationic exchange with the calcium phosphate groups into bone crystals.