The noninvasive cancer treatment uses a combination of harmless, near-infrared light and benign, gold nanoshells to destroy tumors with heat. The treatment does not affect healthy tissue.
"We are extremely encouraged by the results of these first animal tests," said Jennifer West, professor of bioengineering and chemical engineering. "These results confirm that nanoshells are effective agents for the photothermal treatment of in vivo tumors."
Results of the study are published in the June 25 issue of the journal Cancer Letters.
Invented in the 1990s by Naomi Halas at Rice, nanoshells are about 20 times smaller than a red blood cell. The multilayered nanoshells consist of a silica core covered by a thin gold shell. The size, shape and composition of nanoshells give them unique optical properties. By varying the size of the core and the thickness of the gold shell, researchers can tailor a nanoshell to respond to a specific wavelength of light.
The photothermal cancer treatment uses nanoshells that are tuned to respond to near-infrared light. Located just outside the visible spectrum, near-infrared light passes harmlessly through soft tissue. In the treatment, nanoshells convert this light into heat that destroys nearby tumor cells. The heating is very localized and does not affect healthy tissue adjacent to the tumor.
The animal trial involved 25 mice with tumors ranging in size from 3-5.5 millimeters. The mice were divided into three groups. The first group was given no treatment. The second received saline injections, followed by three minutes exposure to near-infrared laser light. The final group received nanoshell injections and laser treatments.