Hydrochalarones: a novel endohedral metallofullerene platform for enhancing magnetic resonance imaging contrast

Abstract

Targeted imaging requires contrast agents that remain in the vasculature for extended periods of time. A new contrast agent is described in which gadolinium is encapsulated within an extremely stable carbon sphere, thus allowing for safe extended residence. Water solubility and small particle size is achieved with novel fullerene chemistry, attaching multiple oligoethylene glycol groups through nitrogen chemistry. These new compounds can be used to visualize tissue architecture in vivo with standard MRI techniques.

Figure 1

(A) General structure of Hydrochalarones is Gd₃N@C₈₀-R_x, where R = −[N(OH)(CH₂CH₂O)_nCH₃]_x where n = 1,3,6 and x is 10–22. (B) Infrared spectra of Hydrochalarone-6.

Figure 2

Coronal slice from a whole-body MRI of a mouse before (left) and 30 min after (right) administration of Hydrochalarone-6. The unidentified bright spot in both the pre- and postcontrast images is likely an artifact.