Long-term in vivo biodistribution and toxicity study of functionalized near-infrared persistent luminescence nanoparticles

Near-infrared (NIR) persistent luminescence nanoparticles (NPLNPs) have become one of the most promising candidates for bioimaging. Different from the other fluorescence nanoprobes, the NIR persistent luminescence of NPLNPs can last for a long time after excitation, double exposure that is nanoparticles and light exist during the long-term bioimaging. However, to date, the potential risk of nanoparticles and NIR persistent luminescence of NPLNPs is still unknown. In this study, Cr3 + -doped zinc gallate, Zn(1.1)Ga(1.8)Sn(0.1)O(4):Cr(3+) (ZGO), the most promising NPLNPs in bioimaging, was chosen as a representative for potential risk assessment. We evaluated the potential risk of nanoparticles and NIR persistent luminescence of ZGO for a long period of time. In vitro study showed that the ZGO possessed a low cytotoxicity. In vivo biodistribution results showed that the ZGO mainly accumulated in the reticuloendothelial system after intravenous injection and could be gradually cleared from the body by digestive system. In addition, the ZGO did not exhibit appreciable toxicity in mice over a period of 60 days. It’s also worth mentioning that long-term NIR persistent luminescence of ZGO did not exhibit obvious toxicities both in vitro and in vivo. Our results provide important information with regards to the risk of NPLNPs in long-term bioimaging.