Incorporation of Gallium-68 into the Crystal Structure of Prussian Blue to Form K68GaxFe1-xFe(CN)6 Nanoparticles: Toward a Novel Bimodal PET/MRI Imaging Agent

摘要

Similarity between the Ga³⁺ 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.