Incorporation of gallium-68 into the crystal structure of Prussian blue to form K68Ga: XFe1- x[Fe(CN)6] nanoparticles: Toward a novel bimodal PET/MRI imaging agent

Abstract

Similarity between the Ga+ ion and the Fe3+ ion allows for partial replacement of Fe3+ ions with Ga3+ ions in the Fe(iii) crystallographic positions in Prussian blue (PB) to form various solid solutions KGaxFe1-x[Fe(CN)6] (0 < x < 1). Such solid solutions possess very high thermodynamic stability as expected from the parent PB structure. Consequently, a simple one-step 68Ga-labeling method was developed for preparing a single-phase nanoparticulate bimodal PET/MRI imaging agent based on the PB structural platform. Unlike the typical 68Ga-labelling reaction based on metal complexation, this novel chelator-free 68Ga-labeling reaction was shown to be kinetically fast under the acidic conditions. The Ga3+ ion does not hydrolyze, and affords the 68Ga-labelled PB nanoparticles, which are easy to purify and have extremely high stability against radionuclidic leaching in aqueous solution.