Developing drugs to combat or cure human disease often involves a phase of testing with mice, so being able to peer clearly into a living mouse's innards has real value.
But with the fluorescent dyes currently used to image the interior of laboratory mice, the view becomes so murky several millimeters under the skin that researchers might have more success divining the future from the rodent's entrails than they do extracting usable data.
Now Stanford researchers have developed an improved imaging method using fluorescent carbon nanotubes that allows them to see centimeters deep into a mouse with far more clarity than conventional dyes provide. For a creature the size of a mouse, a few centimeters makes a great difference.
"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?" said Hongjie Dai, a professor of chemistry. "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."
Researchers inject the single-walled carbon nanotubes into a mouse and can watch as the tubes are delivered to internal organs by the bloodstream.
The nanotubes fluoresce brightly in response to the light of a laser directed at the mouse, while a camera attuned to the nanotubes' near infrared wavelengths records the images.
By attaching the nanotubes to a medication, researchers can see how the drug is progressing through the mouse's body.
Dai is the one of the authors of a paper describing the research published online this month in Proceedings of the National Academy of Sciences.
The key to the nanotubes' usefulness is that they shine in a different portion of the near infrared spectrum than most dyes.
Biological tissues whether mouse or human naturally fluoresce at wavelengths
|Contact: Louis Bergeron|