Studies Involving Electron Paramagnetic Resonance Measurements of Apatitic Crystals and Mineral-Protein Complexes.

摘要

The ESR technique was used to probe the structure of model apatite-like minerals and to compare them with the biological mineral of bone. Unpaired electrons were produced in powdered samples by 60 KVP x-rays at 85degrees K. The majority of ESR signals arose from species at or near the surface. Even in the presence of organic material only resonances from mineral were detected at 85degrees K. These included hydrogen atoms,oxygen anion radicals,phosphate radicals and defect centers. Comparisons of bone mineral and various model minerals showed that the highly crystalline stoichiometric hydrothermal hydroxyapatites are unlike the mineral of bone. Better agreement occurs with certain non-stoichiometric precipitation apatites that have been modified by the presence of organic molecules. Changes in the ESR spectra due to the presence of fluoride and carbonate are reported. The surface location of the radical species made it possible to study the effects of adsorbed organic molecules on the ESR spectra.