The Gadonanotubes revisited: A new frontier in MRI contrast agent design

In this review, the application of the Gadonanotubes (GNTs) as high-performance magnetic resonance imaging (MRI) contrast agents (CAs) is discussed. Through published and some unpublished work, we describe how the loading and nanoscale confinement of multiple Gd3+ ions within ultra-short single-walled carbon nanotubes (US-tubes) produces GNTs with MRI efficacies 40 to 90 times greater than current clinical CAs. Since there is a continuing need to increase MRI sensitivity, the molecular factors affecting the performance of Gd3+-based CAs are described and their optimization is considered for Gd3+-based agents, in general, and the GNTs in particular. The GNTs are new (ca. 2005) high-performance nanotechnology-inspired MRI CAs with promise for advanced T1-weighted MR molecular imaging applications.