April 14, 2003

Tiny particles may make huge medical strides

By Holly Korschun

Until very recently, nanotechnologists—scientists who build devices and materials one atom or molecule at a time—concentrated almost entirely on electronics, computers, telecommunications and materials manufacture. Now biomedical nanotechnology, in which bioengineers construct tiny particles combining inorganic and biological materials, is pushing to the forefront of this rapidly advancing field of science.

Shuming Nie, associate professor of biomedical engineering and director of cancer nanotechnology at the Winship Cancer Institute, highlighted recent research in this area last month at the 225th national meeting of the American Chemical Society in New Orleans.

“We believe biomedical nanotechnology soon will produce major advances in molecular diagnostics, therapeutics, molecular biology and bioengineering,” said Nie, who came to Emory and Georgia Tech’s shared Coulter Department of Biomedical Engineering from Indiana University.

“Already, scientists have begun to develop functional nanoparticles that are linked to biological molecules such as peptides, proteins and DNA,” Nie said.

Nanoparticles assume special properties by virtue of their miniature size that distinguish them from larger particles, including changes in color, as they shrink smaller and smaller. Because of their compact structure, nanoparticles emit light and can act as a fluorescent tag. This makes them highly suitable as contrast agents for magnetic resonance imaging (MRI), in positron emission tomography (PET) for molecular imaging in patients, or as fluorescent tracers in optical microscopy.

Nanoparticles also have advantages over conventional dyes: they fade less quickly, they are less toxic to cells and they can be used in combination to create almost an infinite number of colors.

Although nanoparticles are similar in size to biomolecules such as proteins and DNA, human-made nanoparticles can be engineered to have specific or multiple functions. Bioconjugated quantum dots, consisting of different-sized dots embedded in tiny beads made of polymer material, can be finely tuned to a myriad of different colors that can tag a multitude of different proteins or genetic sequences in a process called “multiplexing.”

By chemically binding the quantum dots to particular genes and proteins, scientists including Nie are developing molecular nanoprobes to rapidly analyze biopsy tissue from cancer patients, to monitor the effectiveness of drug therapy, as scaffolding in tissue engineering, and to deliver controlled amounts of drugs into genetically classified tumor cells.