Fluorescent carbon nanotubes light the way for drug-delivery researchers

Those involved in drug-delivery research often use mice to test whether medication is going where it's supposed to go. However, researchers often get a very cloudy picture when they use traditional dyes to image what's going on inside the rodents. And that's where, again, carbon nanotubes can come to the rescue.

Nano magazine reports on the work of Hongjie Dai at Stanford and his creation of an imaging method using fluorescent carbon nanotubes that allow a deeper view into lab mice. "We have already used similar carbon nanotubes to deliver drugs to treat cancer in laboratory testing in mice, but you would like to know where your delivery went, right?" Dai tells Nano. "With the fluorescent nanotubes, we can do drug delivery and imaging simultaneously--in real time--to evaluate the accuracy of a drug in hitting its target."

Attach the tiny tubes to a medication and then inject them into a mouse. Then, direct a laser at the animal and the nanotubes inside will fluoresce brightly, showing how the drug is progressing through the rodent's body. Nanotubes work because they fluoresce at wavelengths between 1,000 and 1,400 nanometers, whereas mouse (and human) tissue naturally fluoresce at wavelengths below 900 nanometers. So, with the nanotubes, there is barely any natural tissue fluorescence, giving researchers a view almost clear of background noise.

Dai and graduate students Sarah Sherlock and Kevin Welsher observed the fluorescent nanotubes passing through the lungs and kidneys within seconds after injection, Nano reports. The spleen and liver lit up a few seconds later.

- read the story in Nano magazine
- and the abstract in PNAS

Special Report: Carbon nanotubes - When nanotech meets biotech