That’s when the researchers turned to gold as the answer. The element is non-reactive in the human body, and would be the perfect “scaffold” to attach molecules of the drug to in the absence of the ammonium salt, holding the drug molecules together and concentrating their effect.
“The idea is that by attaching these individual molecules of the drug with a weak binding ability to the gold nanoparticle, you can magnify their ability to bind,” Melander says.
The researchers’ theory proved correct. They started with a modified version of TAK-779, which didn’t include the harmful ammonium salt. After testing, they found that attaching 12 molecules of the modified drug (SDC-1721) to one nanoparticle of gold restored the drug’s ability to prevent HIV infection in primary cultured patient cells. When only one molecule of the drug was attached to the gold nanoparticle, the compound was unable to prevent HIV infection, indicating that the multivalency of the drug was important for its activity.
“We’ve discovered a non-harmful way to improve the strength and efficacy of an important drug,” Melander says. “There’s no reason to think that this same process can’t be used with similar effect on other existing drugs.” ###
Note to Editors: an abstract of the paper follows.
"Inhibition of HIV Fusion with Multivalent Gold Nanoparticles"
Authors: Mary-Catherine Bowman, University of North Carolina-Chapel Hill; Christian Melander and T. Eric Ballard, North Carolina State University Daniel Feldheim, University of Colorado at Boulder, et al
Published: May 13, 2008 in Journal of American Chemical Society online
Abstract: The design and synthesis of a multivalent gold nanoparticle therapeutic is presented. SDC-1721, a fragment of the potent HIV inhibitor TAK-779, was synthesized and conjugated to 2.0 nm diameter gold nanoparticles. Free SDC-1721 had no inhibitory effect on HIV infection; however, the (SDC-1721)−gold nanoparticle conjugates displayed activity comparable to that of TAK-779. This result suggests that multivalent presentation of small molecules on gold nanoparticle surfaces can convert inactive drugs into potent therapeutics.
Contact: Tracey Peake tracey_peake@ncsu.edu 919-515-6142 North Carolina State University
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