Core–Shell Lanthanide Upconversion Nanophosphors as Four-Modal Probes for Tumor Angiogenesis Imaging

Multimodality imaging overcomes the shortage and incorporates the advantages of different imaging tools. Lanthanide-based nanoprobes are unique and have rich optical, magnetic, radioactive, and X-ray attenuation properties; however, simple doping of different lanthanide cations into one host can result in a material with multifunction but not the optimized properties. In this study, using NaLuF4:Yb,Tm as the core and 4 nm of (153)Sm(3+)-doped NaGdF4 (half-life of (153)Sm = 46.3 h) as the shell, we developed a lanthanide-based core-shell nanocomposite as an optimized multimodal imaging probe with enhanced imaging ability. The lifetime of upconversion luminescence (UCL) at 800 nm and relaxation rate (1/T1) were at 1044 μs and 18.15 s(-1)·mM(-1), respectively; however, no significant decrease in the attenuation coefficient was observed, which preserved the excellent X-ray imaging ability. The nanomaterial NaLuF4:Yb,Tm@NaGdF4((153)Sm) was confirmed to be effective and applicable for UCL imaging, X-ray computed tomography (CT), magnetic resonance imaging, and single-photon emission computed tomography (SPECT) in vivo. Furthermore, the NaLuF4:Yb,Tm@NaGdF4((153)Sm) nanoparticles were applied in tumor angiogenesis analysis by combining multimodality imaging of CT, SPECT, and confocal UCL imaging, which shows its value of multifunctional nanoparticles NaLuF4:Yb,Tm@NaGdF4((153)Sm) in tumor angiogenesis imaging.