Behavior of Supramolecular Assemblies of Radiometal-Filled and Fluorescent Carbon Nanocapsules In Vitro and In Vivo

Hybrid materials based on supramolecularly assembled single-walled carbon nanotubes (SWNTs) are generated for positron emission tomography (PET), magnetic resonance imaging, and fluorescence imaging. The all-in-one imaging probe allows quantitative imaging from subcellular resolution to whole tissue regions. The SWNTs can be exposed to aqueous solutions of non-radioactive and radioactive metal salts in the presence of fullerenes and β-d-glucan. Encapsulating ⁶⁴Cu ions achieves a minimum of 69% incorporation of radiochemical. The results suggest that this method can be extended to other metal ions of medical relevance, such as zirconium(IV)-89 or rhenium(VII)-188, which are used for medical imaging or radiotherapy, respectively. The in vivo uptake of ⁶⁴Cu(II)@SWNT@β-d-glucan in Wistar rats allows the investigation of organ biodistribution by microPET. Radioactivity rapidly accumulates predominantly in the lungs and myocardium with peak uptakes of 4.8 ± 0.9 standardized uptake value. Furthermore, such materials are fully traceable in cells by multiphoton fluorescence lifetime imaging with near-infrared excitation (910 nm).