Preparation and Characterization of Mono- and Biphasic CaAgHPO·nHO Compounds for Biomedical Applications.

This study aimed to explore the effects of the full-scale replacement (up to 100%) of Ca ions with Ag ions in the structure of brushite (CaHPO·2HO). This substitution has potential benefits for producing monophasic and biphasic CaAgHPO·nHO compounds. To prepare the starting solutions, (NH)HPO, Ca(NO)·4HO, and AgNO at different concentrations were used. The results showed that when the Ag/Ca molar ratio was below 0.25, partial substitution of Ca with Ag reduced the size of the unit cell of brushite. As the Ag/Ca molar ratio increased to 4, a compound with both monoclinic CaHPO·2HO and cubic nanostructured AgPO phases formed. There was a nearly linear relationship between the Ag ion ratio in the starting solutions and the wt% precipitation of the AgPO phase in the resulting compound. Moreover, when the Ag/Ca molar ratio exceeded 4, a single-phase AgPO compound formed. Hence, adjusting the Ag/Ca ratio in the starting solution allows the production of biomaterials with customized properties. In summary, this study introduces a novel synthesis method for the mono- and biphasic CaAgHPO·nHO compounds brushite and silver phosphate. The preparation of these phases in a one-pot synthesis with controlled phase composition resulted in the enhancement of existing bone cement formulations by allowing better mixing of the starting ingredients.