When conducting drug testing on laboratory mice, it's often useful to image the internal organs of the animals in detail. While there are accurate methods such as MRI or CT scans, the associated cost and complexity of these systems is not a very efficient solution. A cheaper and simpler technique involves injecting the animals with fluorescent dyes that are diffused into the blood stream and channeled to the internal organs.
The drawback of traditional fluorescent dyes is that the images generated are only useful at a depth of a few millimeters. Anything deeper and the reflection from the dyes causes the images to appear foggy. The main reason for this limitation is that biological tissue has some natural fluorescent properties at the same wavelength as the dyes. In addition, the tissue has a tendency to scatter light at this frequency.
This May, a team of scientists in Standford University, announced that they had created a dye composed of carbon nanotubes designed to fluoresce at that was different than the natural fluorescent properties of biological tissue. This greatly minimizes light scatter. They have been able to image the tissue of mice at a depth of several millimeters without the haziness and distortion that occurs with regular dyes.
The team has previously used similar nanotubes as drug delivery system and they now expect that the imaging aspect of this technology can be added to the delivery systems for enhanced performance. Hongjie Dai, a professor of chemistry at Stanford explained in a university press release that "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."