Gd-Encapsulated Carbon Nanotubes as Dual-Modal Probes for Magnetic Resonance and Second Near-Infrared Emission

We report a second near-infrared (NIR-II) fluorescence and magnetic resonance (MR) dual-modal probe composed of fluorescent carbon nanotubes (CNTs) encapsulated with paramagnetic Gd compounds. The Gd-filled CNTs are synthesized via a vapor-phase technique using gadolinium halides as precursors, and the CNTs exhibit the strong photoluminescence even after Gd filling. We have investigated NIR-II fluorescence and MR imaging in vivo as well as in vitro, demonstrating that the Gd-filled CNTs can be used for dual-modal imaging of tissues and vessels in living mice, creating avenues for disease diagnosis and prognosis.