Monday, June 15, 2009

Carbohydrate-Capped Quantum Dots Target Liver

Could lead to drugs that seek specific organs

Quantum dots (QD) capped with certain sugars accumulate selectively in the livers of mice, researchers in Switzerland report. The ability to target the liver through carbohydrate-protein interactions could lead to the development of drug delivery methods that seek out specific organs, one of the researchers said.

Carbohydrate-capped quantum dots accumulated selectively in the livers of mice.

"QDs are not suitable to be directly used for therapeutic purposes," said Bernd Lepenies, PhD, of the Free University of Berlin, in an e-mail to PFQ. "The study was aimed to demonstrate that carbohydrates can be utilized for specific uptake of particles into cells. It is expected that cell-specific drug delivery strategies (e.g., using polymers, dendrimers, or liposomes as vehicles) can be invented on the basis of our work."

The researchers found that carbohydrate-capped QDs became three times more concentrated in the livers of mice than regular dots—the first time this has been shown in vivo, Dr. Lepenies told PFQ.

"Our study shows that carbohydrates are useful to target substances (e.g., drugs) specifically to cells or organs," Dr. Lepenies said. "This might allow researchers to use carbohydrate-based targeting systems for cell-specific drug delivery, MRI, near-infrared frequency imaging, and photothermal therapy in the future."

Our study shows that carbohydrates are useful to target substances (e.g., drugs) specifically to cells or organs.
Bernd Lepenies, PhD, Free University of Berlin

He said other organs, including the brain and kidney, also have carbohydrate-recognizing receptors, so it may be possible to develop drugs that target those organs as well. Targeting drugs to cancer cells with greater specificity may reduce chemotherapy side effects, he said.

Dr. Lepenies is currently leader of the glycoimmunology research group at the Max Planck Institute of Colloids and Interfaces in Berlin. He was a postdoctoral researcher in the organic chemistry laboratory of Peter Seeberger, PhD, at the Swiss Federal Institute of Technology in Zurich, Switzerland, when the recently published research was performed. (Kikkeri R, Lepenies B, Adibekian A, et al. In vitro imaging and in vivo liver targeting with carbohydrate capped quantum dots. J Am Chem Soc. 2009;131(6):2110-2112.)

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