Lanthanide ion-doped GdPO4 nanorods with dual-modal bio-optical and magnetic resonance imaging properties

Here, dual-modal bioprobes for combined optical and magnetic resonance (MR) imaging are reported. Gadolinium orthophosphate (GdPO4) nanorods co-doped with light-emitting lanthanide ions have been successfully prepared through a hydrothermal method. An efficient downconversion luminescence from Ce/Tb or Eu doped GdPO4 nanorods and upconversion luminescence from Yb/Er co-doped GdPO4 nanorods are observed, respectively, which offers the optical modality for the nanoprobes. Notably, we first report the upconversion phenomenon based on the GdPO4 matrix under 980 nm near infrared irradiation. The possibility of using these nanoprobes with downconversion and upconversion luminescent emissions for optical cell imaging is also demonstrated. Furthermore, these Gd3+-containing nanophosphors show good positive signal-enhancement ability when performed under a 4.7 T MR imaging scanner, indicating they have potential as T-1 MR imaging contrast agents. Thus, nanoprobes based on GdPO4 nanophosphors are shown to provide the dual modality of optical and MR imaging.