Gold Nanoparticle Probes Identify Tumors Under the Skin

Tiny gold particles embedded with dyes have been used to identify human tumors under the skin of a living animal. These nanoparticle probes may allow doctors to detect and diagnose cancer in man earlier and less invasively.

The gold particles described in a new study were linked with single chain variable fragment (ScFv) antibodies that recognize epidermal growth factor receptor (EGFR), which is present on the surface of many human tumors including head and neck and lung carcinomas. Covered with a non-toxic polymer, the gold particles are about 60-80 nanometers in diameter. That is 150 times smaller than a typical human cell and thousands of times smaller than a human hair. The antibody-linked particles accumulate in tumors ten times more than gold particles without antibodies.

In the study, which was led by Dr. Shuming Nie at the Emory-Georgia Tech Cancer Nanotechnology Center of Excellence (CCNE, Atlanta, GA, USA) the ScFv peptides bound cancer cells as the gold particles grasped human tumor cells after their injection into a mouse. When illuminated with a laser beam, the tumor-bound particles sent back a signal that is specific to the dye. The antibody-linked particles accumulated in tumors ten times more than gold particles without antibodies.

The results of the study appeared in the online journal Nature Biotechnology on December 23, 2007. In the article the scientists reported they are able to detect human cancer cells injected into a mouse at a depth of 1-2 cm. That makes the gold particles especially appropriate tools for gathering information about head or neck tumors, which tend to be more accessible.

Dr. Nie said that his lab plans to modify the coatings of the nanoparticles to improve tumor targeting. Eventually, he says, the gold particles could also be used to selectively deliver drugs to cancer cells.


Related Links:
Emory-Georgia Tech Cancer Nanotechnology Center of Excellence