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Nanotech News


September 25, 2006

All-At-Once Detection of Multiple Disease Markers

When pathologists examine tissue samples in order to diagnose cancer of the lymphatic system, they examine the relative amounts of a group of proteins known as Cluster of Differentiation markers. Typically, this is a painstaking process, but new findings from investigators at the National Cancer Institute (NCI) show that quantum dots may be able to greatly simplify the process for examining the entire panel of Differentiation markers at once.

Reporting its work in the journal Modern Pathology, a team of investigators led by Stefania Pittaluga, M.D., Ph.D., at the NCI, describe the use of antibodies linked to quantum dots, in combination with a technique known as multispectral imaging, to detect 11 Cluster of Differentiation markers in fixed human lymphoid tissue samples. The researchers attached quantum dots with unique emission spectra – the color of light they emit when irradiated with light – to each of 11 commercially available antibodies that target these Differentiation markers. A meticulous series of experiments identified which color quantum dot worked best for detecting each of the antibodies.

Using these matched antibody-quantum dot conjugates, the investigators then showed they could detect and quantify five pairs simultaneously in fixed human lymphoid tissue. They accomplished this task using a confocal fluorescence microscope, and the researchers note that the quantum dots produced a bright signal with little background staining. This signal was far more stable over time than that given off by standard fluorescent dyes, permitting the investigators to image the sample multiple times without any change in the observed signal.

The researchers note that while their study validates the development of multi-target quantum dot-based diagnostic systems, there are still many factors that need to be examined to optimize the use of these nanoscale beacons. However, given the payoff in terms of ultimate ease of use and increased sensitivity, such studies should be conducted in the near future.

This work, which was funded by the National Cancer Institute, is detailed in a paper titled, “Multispectral imaging of clinically relevant cellular targets in tonsil and lymphoid tissue using semiconductor quantum dots.” An investigator from George Mason University also participated in this study. An abstract of this paper is available through PubMed.
View abstract.