Low Toxicity, High Resolution, and Red Tissue Imaging in the Vivo of Yb/Tm/GZO@SiO2 Core–Shell Upconversion Nanoparticles

Abstract Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted great attention in bioimaging applications. However, the stability and resolution of bioimaging based on UCNPs should be further improved. Herein, we synthesized SiO2-coated Ga(III)-doped ZnO (GZO) with lanthanide ion Yb(III) and Tm(III) (Yb/Tm/GZO@SiO2) UCNPs, which realized red fluorescence imaging in heart tissue. With increasing injection concentrations of Yb/Tm/GZO@SiO2 (1–10 mg/kg), the red fluorescence imaging intensity of heart tissue gradually increased. Moreover, the experimental results of toxicity in vitro and histological assessments of representative organs in vivo were studied, indicating that Yb/Tm/GZO@SiO2 UCNPs had low biological toxicity. These results proved that Yb/Tm/GZO@SiO2 can be used as a probe for fluorescence imaging in vivo.