NaGdF4:Yb3+/Er3+@NaGdF4:Nd3+@Sodium-Gluconate: Multifunctional and Biocompatible Ultrasmall Core-Shell Nanohybrids for UCL/MR/CT Multimodal Imaging

Multimodal bioimaging nanoparticles by integrating diverse imaging ingredients into one system, represent a class of emerging advanced materials that provide more comprehensive and accurate clinical diagnostics than conventional contrast agents. Here monodisperse and biocompatible core shell nanoparticles, NaGdF4: Yb3+/Er3+@NaGdF4:Nd@sodium-gluconate (termed as GNa-Er@Nd), with about 26 nm in diameter were successfully prepared by a facile two step reactions in high boiling solvents, and followed a ligand exchange process with sodium gluconate. The resulting GNa-Er@Nd nanopartides were well characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), and zeta potentials. These nanohybrids present brightly dual-wavelength excited upconversion luminescence (UCL) under both 980 and 793 nrn laser because of the synergistic effect of Yb3+/Er3+ and Nd3+. They also exhibited excellent relaxivity parameters (r(1)) in magnetic resonance imaging (MRI) and Hounsfield units (HU) in Xray computed tomography (CT) that are comparable to the clinical contrast agents. Therefore, these small and monodisperse nanopartides provide options to construct a unique platform for potential multimodal UCL/CT/MRI imaging simultaneously.