Investigators at the Université Pierre et Marie Curie in Paris, France, have developed a versatile new method for creating nanoparticles that are both magnetic and fluorescent, says a report at nanotechwire:

The researchers then used the nanoparticles created with this method to label and image live cells. They note that these particles could be used to track cell movements within the body and to help separate different cell types in basic research and diagnostic applications.

When the researchers added nanoparticles labeled with the fluorescent dye rhodamine to cancer cells growing in culture, they were able to observe that the nanoparticles attached themselves to the outer cell membrane. While viewing the now-labeled cells using a fluorescent microscope, the investigators were able to follow the nanoparticles as the cells transported them through the cell membrane and into internalized compartments known as endosomes.

Once the nanoparticles were inside the cells, the researchers applied a magnetic field to the culture dish, turning the nanoparticle-filled endosomes into internal magnets. Like any set of magnets, the endosomes were attracted to one another, forming small chains in the cell cytoplasm.