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

Abstract Utilizing the solvothermal method, a nanoprobe of NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 was synthesized by deposition of a layer of NaGdF 4 on the NaYF 4 :Yb 3+ ,Er 3+ upconverting nanoparticles (UCNPs). Then, NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 @TaO x core@shell@shell nanoparticles were prepared via decorating the radiopaque but fluorescence-transparent TaOx onto the surface of NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 by a facile reverse microemulsion strategy. The structure of the NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 @TaO x 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 NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 @TaO x nanoparticle can be employed as multimodal nanoprobe for bioimaging applications. Furthermore, the feasibility of NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 @TaO x 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 NaYF 4 :Yb 3+ ,Er 3+ @NaGdF 4 @TaO x hold great potential for multimodal in vivo imaging.