Biodistribution of Vanadium Dioxide Particles in Mice by Consecutive Gavage Administration: Effects of Particle Size, Dosage, and Health Condition of Mice.

The newly developed vanadium dioxide (VO2), a material with excellent reversible and multi-stimuli responsible phase transition property, has been widely used in high-performance and energy-saving smart devices. The rapid growth of the VO2-based emerging technologies and the complex biological effect of vanadium to organisms urge a better understanding of the behavior of VO2 in vivo for safety purpose. Herein, we study the absorption, distribution, and excretion of two commercial VO2 (nanoscale SVO2 and bulk MVO2) in mice after consecutive gavage administration for up to 28 days. The absorption of both types of VO2 is as low as less than 1.5% of the injected dose within 28 days, while MVO2 is several times more difficult to be absorbed than SVO2. Almost all unabsorbed VO2 is excreted through feces. For the absorbed vanadium, bone is the organ with the largest accumulation, followed by liver, kidney, and spleen. The vanadium content in organs shows a size-, dosage-, and animal health condition-dependent manner, and increases gradually to a saturation value along with the consecutive administration. Generally, smaller particle size and higher dosage lead to higher vanadium contents in organs, and more vanadium accumulates in bone and liver in diabetic mice than in normal mice. After the treatment is stopped, the accumulated vanadium in organs decreases a lot within 14 days, even reaches to the background level in some organs, but the content of vanadium in the bone remains high after 14 days post-exposure. These findings provide basic information for the safety assessment and safe applications of VO2-based materials.