Abstract: BACKGROUND AND AIM: To study the biodistribution of the 125I labeled tyrosine-multiwalled carbon nanotubes via a single tail vein injection in ICR mice. MATERIALS AND METHODS: Tyrosine-multiwalled carbon nanotubes were prepared and labeled by 125I. Healthy adult female ICR mice received intravenous injection of 125I marked tyrosine-multiwalled carbon nanotubes. The mice were sacrificed at 10 min, 30 min, 1 h, 6 h, 12 h, 24 h and 48 h after injection. The tissues, including the blood, heart, liver, spleen, lung, kidney, brain, muscle, bone, stomach, intestine, skin and thymus gland, were immediately dissected. Each tissue was weighed and counted for 125I activity. The distribution in the tissues was represented by the percent of the injected dose per gram of tissue(％ID/g). RESULTS: 125I activity was mainly detected in the lung and without significant reduction at 48 h after injection (P>0.05). The second highest level was found in the kidney but rapidly declined within 48 h (P<0.05). 125I activity was found accumulated and remained constant in the liver and spleen. The 125I activity was very low in blood, heart, muscle, bone, stomach, intestine, skin and thymus gland and continuous decreased within 48 h. Lastly, it was rarely detected in brain. CONCLUSION: Intravenous tyrosine-multiwalled carbon nanotubes were mainly distributed in the lung of ICR mice and might be stored in the lung, liver and spleen.

Key words: multi-walled carbon nanotubes, tyrosine, 125I labeling, mice, biodistribution