Study of 223Ra uptake mechanism on hydroxyapatite and titanium dioxide nanoparticles as a function of pH

摘要

The mechanism of ~(223) Ra uptake on hydroxyapatite and titanium dioxide nanoparticles was studied as a function of pH. Both materials are widely used in food industry and medicine. They offer properties suitable for labelling with medicinal radionuclides, particularly for targeted radionuclide therapy. The selected isotope, ~(223) Ra, is an alpha emitter widely used in targeted alpha particle therapy due to high-dose delivery in very small tissue volume, nevertheless the results are applicable for any radium isotope including ~(226) Ra. The study was performed in the pH range 4.5 to 12 for hydroxyapatite nanoparticles and 2 to 12 for titanium dioxide nanoparticles in Britton–Robinson buffer solution. Both nanomaterials at pH 6 and higher showed that over 95% of the radium has been sorbed. According to the applied chemical equilibrium model, the most important species playing a role in sorption on the edge-sites were RaCO _(3) , RaPO _(4) ~(?) , RaHPO _(4) and Ra(Ac ~(?) ) _(2) , and Ra ~(2+) and RaH _(2) PO _(4) ~(+) on layer-sites. All experiments were conducted under free air conditions and no negative impact of CO _(2) was found. The surface complexation model was found suitable for describing radium uptake by the studied hydroxyapatite and titanium dioxide nanomaterials.