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Hydroxyapatite (HAp) is one the main mineral bones and teeth components and biocompatible material used in orthopaedic implants. It might be used as a drug carrier in diagnostics and treatment of cancer. The sufficient in vivo stability without fast aggregation of the Hap-NPs is required for theranostic application. Various phosphonic acids were studied as potential HAp stabilisers and technetium-99m chelator.
Hydroxyapatite nanoparticles were prepared by precipitation of Ca(NO3)2 with (NH4)2HPO4 at pH=11. The precipitate was washed, lyophilized and crushed. Stabilized samples were prepared from already-made HAp-NPs by ultrasound dispergation in corresponding phosphonic acid solution in water (1 mg/ml).
The hydrodynamic size distributions of studied stabilized particles were determined using dynamic light scattering (Zetasizer, Malvern, UK). Samples were labelled with technetium-99m eluted from 99Mo/99mTc generator (DRYTEC, GE Healthcare). The labelling yield ranged to about 90 %. Subsequent in vitro stability studies were carried out in bovine serum, bovine plasma, saline and 5% albumin solution. Measurements of released activity revealed that samples exhibit the highest stability in saline (released activity of about 10 %). The lowest stability was shown to be in blood plasma (released activity of about 20 %).
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This work was supported by Ministry of the Interior of the Czech Republic, grant no. VI20172020106 and the EU & Ministry of Education Youth and Sports of the Czech Republic grant No.: CZ.02.1.01/0.0/0.0/15_003/0000464.
