Synthesis of NaYF4:Yb3+,Er3+@NaGdF4@TaOx Multimodal Nanoprobe for Bioimaging Applications

Utilizing the solvothermal method, a nanoprobe of NaYF4:Yb3+,Er3+@NaGdF4 was synthesized by deposition of a layer of NaGdF4 on the NaYF4:Yb3+,Er3+ upconverting nanoparticles (UCNPs). Then, NaYF4:Yb3+,Er3+@NaGdF4@TaOx core@shell@shell nanoparticles were prepared via decorating the radiopaque but fluorescence-transparent TaOx onto the surface of NaYF4:Yb3+,Er3+@NaGdF4 by a facile reverse microemulsion strategy. The structure of the NaYF4:Yb3+,Er3+@NaGdF4@TaOx nanoparticle was characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and energy-dispersive X-ray analysis (EDS). The X-ray attenuation, magnetic and upconversion luminescent studies suggest that the as-prepared NaYF4:Yb3+,Er3+@NaGdF4@TaOx nanoparticle can be employed as multimodal nanoprobe for bioimaging applications. Furthermore, the feasibility of NaYF4:Yb3+,Er3+@NaGdF4 @TaOx for CT/MRI in vivo has been demonstrated. The brightness enhancement of MRI and CT signals in the tumor region were clearly observed at prolonged post-injection to 0.5 h, indicating that the NaYF4:Yb3+,Er3+@NaGdF4 @TaOx hold great potential for multimodal in vivo imaging.