Special report: Mining for medical gold

by Sruthi Valluri, DOTmed News | September 28, 2011

Nanotubules deliver the goods
Meade and Ho’s group at Northwestern is not the only lab to be pursuing this line of research. Dr. Lon J. Wilson, a professor of chemistry at Rice University, has been working with a different kind of nanoparticle called nanotubules. Wilson’s nanotubules are hollow and measure only one nanometer in length. While nanodiamonds carry gadolinium on the outside, Wilson and his group placed the gadolinium ions on the inside of these tubules.

Wilson calls this combination of nanotubes and gadolinium gadonanotubes. He says the benefit of the nanotubule is that it acts as a sheath, protecting patients from the toxicity associated with gadolinium. The gadonanotubes produced images that were at least 40 times more effective than the best clinical agents.

Wilson attributes this improvement to the scale at which nanoparticles operate. With five to ten gadolinium ions confined in the small space of a nanotubule, the contrast agent’s effect is amplified.

“The success of the gadonanotubes is really an effect of nanotechnology,” explains Wilson. “The nanotechnological approach to imaging is a new paradigm in contrast agent design and execution.”

According to Meade, the advantage of nanoparticles is not limited to reducing dosages and toxicity. Nanoparticles also offer the opportunity to combine two fields that had previously been separate in imaging: therapeutics and diagnostics.

Meade compares nanodiamonds to UPS trucks, a nontoxic delivery system for his choice of contrast agents and therapeutics. “They give us a platform on which to decorate a material with both diagnostics and therapeutics,” says Meade, a professor of chemistry, molecular biosciences, neurobiology and radiology at Northwestern.

This feature of nanoparticles—their seemingly unlimited ability to bind to and deliver a range of compounds simultaneously—is what makes them so intriguing for use in imaging. By covalently bonding nanoparticles to contrast agents and therapeutic compounds at the same time, physicians gain a new perspective.
“We call this theranostics, the combination of therapeutics and diagnostics,” Meade says. This combination may allow clinicians to “fate-map,” or follow, therapeutic compounds—like cancer drugs—as they move through the body. Wilson’s group is also headed in the same direction. They are researching the potential of cancer therapy where nanoparticles deposit therapeutics at specific sites while providing clinicians an opportunity to monitor their progress using MRI.

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