One-step destruction of cancer cells

A new approach to fighting cancer, based on nanoscale particles that can detect and destroy cancerous cells, has been developed by researchers at Rice University, Houston, Tex. Current molecular imaging approaches only detect the cancer but do not offer a method of treatment, point out Rebekah Drezek and Jennifer West, professors in the Department of Bioengineering.

"You can look for a molecular marker that may indicate a significant clinical problem, but you can't do anything about it [just through imaging]," indicates Drezek. "We don't want to simply find the cancerous cells. We would like to locate the cells, be able to make a rational choice about whether they need to be destroyed and, if so, proceed immediately to treatment."

Drezek and West collaborated to develop a new imaging and treatment method based on metal "nanoshells"--tiny spheres of silica coated with a thin layer of gold. Because these spheres are constructed on the nanometer scale (one-billionth of a meter, the range where molecular interactions take place), they exhibit unique size-dependent behavior, such as tunable optical properties. This process allows researchers to design particles that scatter and absorb light at particular wavelengths.

The scattering of light provides the optical signal used to detect the cancer cells, which then "light up" when they come into contact with the nanoshells. In this study, the researchers designed the nanoshells to look for breast cancer biomarkers on the surface of the cancer cells. The technique readily can be extended to target other types of cancer or disease processes.

This approach has some significant advantages over other alternatives that are under development, maintains Drezek. For instance, optical imaging is much faster and less expensive than other medical imaging techniques. Gold nanoparticles also are more biocompatible than other types of optically active nanoparticles.

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