Nanotech News

July 11, 2005

Magnetic Nanoprobe Detects Molecular Interactions in Live Cells

Researchers have developed numerous drugs for treating cancer and other diseases without knowing what proteins these drugs interact with in cells. Now, using biocompatible magnetic nanoparticles, a Korean research team has developed a versatile method of identifying the cellular molecules that drugs interact with in living cells. This technique should not only allow investigators to more easily tease out the molecular details of how a drug works, but to also spot potential adverse side effects early in the drug development process.

Reporting their work in the journal Science, a group of investigators led by Tae Kook Kim, Ph.D., from the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, describe the technique - named MAGIC, short for magnetism-based interaction capture - that they use to monitor the interactions between a small drug molecule and its target proteins within a cell. First, the researchers prepare biocompatible magnetic iron oxide nanoparticles that have three different molecules on their surfaces: the drug molecule of interest, a small protein fragment that the human immunodeficiency virus uses to fuse with cells, and a fluorescent label. They then add this multifunctional nanoparticle to a large panel of cells, each of which has been engineered to produce one of its proteins linked to the fluorescent marker known as enhanced green fluorescent protein (EGFP), a standard method widely used in molecular biology.

After allowing the cells to import the labeled magnetic nanoparticles, the researchers then apply a focused magnetic field, which serves to concentrate the magnetic nanoparticles within the live cells. The concentrated nanoparticles are then readily viewed using a confocal fluorescence microscope, enabling the researchers to pick out the cells in which both fluorescent labels - one on the nanoparticle, the other on a target protein - are located at the focused magnetic field. The investigators then use standard molecular biology tools to identify which proteins have interacted with the drug molecule. The paper in Science presents several examples demonstrating the versatility of this procedure.

This work is detailed in a paper titled, "A magnetic nanoprobe technology for detecting molecular interactions in live cells." Investigators from CGK Co. Ltd., also based in Daejeon, South Korea, participated in this study. An abstract is available through PubMed.
View abstract.