Marcel Bruchez, principal scientist at the Quantum Dot Corporation, collaborated on the project. Other collaborators at MBIC include Christopher Lagerholm and Alan Waggoner.
"Our findings are a promising step toward using quantum dots for non-invasive imaging in humans to monitor and treat diseases such as cancer," said Ballou. "Using our modified quantum dots, we were able to non-invasively image structures in living mice by fluorescence, then prove that the quantum dots were present by electron microscopy. No other fluorescent label lets you verify its exact location on scales from the whole animal to molecular dimensions."
Scientists also could modify the surface of these long-lived quantum dots by attaching both biological and non-biological molecules, thereby altering the properties of quantum dots to accomplish a specific goal, noted Ballou. By attaching molecules to the surface of quantum dots, one could target tumors to image them more effectively and allow surgeons to remove cancers with greater accuracy, according to Ballou. "Before these applications can happen, quantum dots must first be modified so that they remain in circulation long enough, and we must ensure that quantum dots cause no toxicity in healthy cells," he said.
To increase the time quantum dots remained circulating in live animals, the researchers coated their surfaces with one of three polyethylene glycol amine (PEG) molecules of varying lengths. They then monitored the circulating lifetimes of each quantum dot variant using non-invasive imaging techniques. While the paper reports initial success at visualizing the quantum dots over four months, the long-term experiment is still continuing, and Ballou has demonstrated that the PEG-coupled Qdot Particles have
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Contact: Lauren Ward
wardle@andrew.cmu.edu
412-268-7761
Carnegie Mellon University
16-Jan-2004