Nanotech News

August 29, 2005

Engineering Gold Nanocages for Optical Imaging, Thermal Therapy of Tumors

One hundred and fifty years after one of the founders of chemistry first created gold nanoparticles and observed that these nanoparticles absorbed light, researchers have created a 21^st century version that absorbs light so efficiently that a mere flash of light can cause the particles to melt. This ability to efficiently turn light into extreme heat could prove useful for creating nanoscale thermal scalpels capable of killing cancer cells.

Expanding on research published earlier this year (click here for previous story), a research team headed by Younan Xia, Ph.D., of the University of Washington, has shown that it can engineer the structure of gold nanocages to fine-tune the wavelength of light that these nanostructures absorb, from blue to near-infrared light, and how much light they can absorb. For example, nanocages that are 36 nanometers wide, absorb light over 10,000 times better than conventional organic dyes, making them potential candidates for optical imaging applications of small tumors. The research team also found that their nanocages absorb light so efficiently that the light from a camera flash actually melted the nanocages, converting them into spherical nanoparticles.

In additional studies, the investigators developed a simple method of attaching targeting agents to the nanocages. This procedure involves only two steps – mixing the nanocages with the target and then centrifuging to separate the starting materials from the conjugated nanocages. In one example, the researchers attached an anti-HER2 antibody to the nanocages and showed that this construct was able to target breast cancer cells that overproduce the HER2 cell-surface receptor. The research team plans to test whether such targeted nanocages can function as a therapeutic agent for heat-induced destruction of tumors. (To see earlier stories on thermal destruction of tumors using nanoparticles, click here and here.)

This work is detailed in a paper titled, “Gold Nanocages: Engineering Their Structure for Biomedical Applications.” Researchers from the Chinese Academy of Sciences also participated in this study, which was posted online in advance of print publication. An abstract is available at the journal’s website.
View abstract.