Surfactant-Free Aqueous Synthesis of Novel Ba2GdF7:Yb3+, Er3+@PEG Upconversion Nanoparticles for in Vivo Trimodality Imaging

In this work, we developed the surfactant-free aqueous synthesis of novel polyethylene glycol (PEG) coated Ba₂GdF₇:Yb³⁺, Er³⁺ upconversion nanoparticles (named as, Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs) for in vivo multimodality imaging including upconversion luminescence (UCL), X-ray computed tomography (CT), and T₁-weighted magnetic resonance (MR). The as-prepared Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs not only present bright UCL and reasonably high CT/MR enhancements but also exhibit excellent colloidal stability, inappreciable cytotoxicity, and negligible organ toxicity. In particular, the Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs emit red UCL with high intensity in the tumor site after intravenous injection via the tail vein of a nude mouse. The Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs as contrast agents exhibit high-performance for in vivo trimodality (UCL/CT/MR) imaging of a tumor during HepG2 tumor-bearing nude mouse experiments.