Ions release from hydroxyapatite and substituted hydroxyapatites in different immersion liquids: In vitro experiments and theoretical modelling study

The multi-substituted hydroxyapatites (ms-HAPs) are currently gaining more consideration due to their multifunctional properties and biomimetic structure, owning thus an enhanced biological potential in orthopedic and dental applications. In this study, nano hydroxyapatite (HAP) substituted with multiple cations (Sr2+, Mg2+ and Zn2+) for Ca2+ and anion (SiO44-) for PO43- and OH-, specifically HAPc-5%Sr and HAPc-10%Sr (where HAPc is HAP-1.5%Mg-0.2%Zn-0.2%Si), both lyophilized noncalcined and lyophilized calcined, were evaluated for their in vitro ions release. These nanomaterials were characterized by SEM, FE-SEM and EDX, as well as by AFM images and by surface-specific areas and porosity. Further, the release of cations and of phosphate anions were assessed from nano HAP and ms-HAPs, both in water and in simulated body fluid (SBF), in static and simulated dynamic conditions, using inductively coupled plasma optical emission spectrometry (ICP-OES). The release profiles were analyzed and ...