Gadolinium Oxide Ultranarrow Nanorods as Multimodal Contrast Agents for Optical and Magnetic Resonance Imaging

We demonstrate a simple synthetic strategy for the fabrication of single-phase rare earth (RE) doped gadolinium oxide (Gd2O3:RE where RE = terbium (Tb), ytterbium (Yb), and erbium (Er)) nanorods (NRs) as multimodal imaging probes. The NRs are ultranarrow and exhibit both emission and magnetic characteristics. The Tb-doped and Yb/Er-codoped Gd2O3 NRs exhibit down- and up-conversion fluorescence respectively, and also exhibit paramagnetism. Importantly, these codoped NRs possess excellent magnetic characteristics, as shown in their longitudinal relaxation time (TI) -weighted image contrast, which is closer to that of commercial Gadovist for magnetic resonance imaging (MRI) applications. This property opens up new avenues in the development of contrast agents.