Neodymium-doped NaHoF nanoparticles as near-infrared luminescent/T-weighted MR dual-modal imaging agents in vivo.

The achievement of efficient near-infrared (NIR) luminescence of lanthanide ions in a paramagnetic nanoparticle (NP) host is highly desirable to optimize the performance of multimodal bioprobes. Herein, we present a facile coprecipitation method to prepare highly uniform NaHoF:Nd nanoplates. Upon NIR excitation at 785 nm, efficient NIR luminescence of Nd can be obtained from the paramagnetic NaHoF hosts. More interestingly, due to energy transfer from the excited state of Nd to the adjacent Ho, NIR emission at around 1200 nm from Ho ions is also observed. The r value of NaHoF:Nd NPs reaches 143.7 s mM at a high magnetic field of 11.7 T. By modifying with hydrophilic alpha-cyclodextrin, the NaHoF:Nd NPs were further successfully applied for the NIR luminescent/T-weighted MR dual-modal in vivo imaging of nude mice, high contrast NIR imaging of the liver and T-weighted MR imaging of stem cells in the mouse brain using the NaHoF:Nd NPs as multimodal bioprobes.