The features of aliovalent substitution in anionic and cationic sublattices of apatite-related calcium phosphate

Abstract

We investigated the features of complex substitution in anionic (PO43–CO32–) and cationic (Ca2+M+, M+ – Na, K) sublattices of apatite-type calcium phosphate during wet precipitation. The nanoparticles (10–35 nm) of apatite-related calcium phosphates were prepared from the aqueous solutions of the system М+–Ca2+–CO32––PO43––NO3– at determined molar ratios Ca2+/PO43–=1.67, CO32–/PO43–=1.0 and М+/PO43–=3.0 and 6.0 at the temperature of 250C. The positions of characteristic vibrations of carbonate groups in the FTIR spectra of the prepared samples in the regions of 1500–1400 cm–1 and 880–870 cm–1 confirmed the realization of partial substitution of РО43– by CО32– (B-type) in apatite-type structure. Results of elemental analysis indicated that the presence of potassium cations in the initial solution promoted the anionic substitution in calcium phosphate structure. The study of the activity of the synthesized carbonate-containing calcium phosphates in vitro revealed their tendency to gradual dissolution without a significant effect on the pH of the medium, which indicates the prospects of the synthesized samples in bone engineering.