Gold Nanospheres Show Promise in 'Boiling' Out Cancer

Mar. 24 --

MONDAY, March 23 (HealthDay News) -- Researchers say that using microscopic gold particles that target melanoma cells and then "boil" them when exposed to certain lighting holds promise as a new treatment for the deadly skin cancer.

The treatment uses gold nanospheres guided directly to the melanoma cells by a special protein fragment called a peptide placed inside the nanosphere. Using a technique known as photoablation therapy (PAT), doctors expose the tumors to near infrared light, causing the nanospheres to heat up and destroy the cancer while leaving healthy tissue alone.

Studies done on mice with melanoma tumors found the peptide-laced nanoparticles were eight times more effective in killing the cancer than those without the peptide guidance system, according to researchers who were to present the findings at an American Chemical Society meeting in Salt Lake City.

"This technique is very promising and exciting," study co-author Jin Zhang, a professor of chemistry and biochemistry at the University of California in Santa Cruz, said in a news release issued by the conference sponsor. "It's basically like putting a cancer cell in hot water and boiling it to death. The more heat the metal nanospheres generate, the better."

According to the U.S. National Cancer Institute, more than 62,000 cases of melanoma were diagnosed in the United States in 2008, and more than 8,400 people die each year from the disease.

The findings are significant because PAT can accidentally destroy healthy skin cells if the light exposure is not administered carefully and closely monitored. Though the use of metal nanoparticles that are smaller than a speck of dust has improved the technique, researchers have been trying to perfect them to destroy the most cancer with the least damage to healthy cells.

The peptide-loaded nanospheres developed by Zhang appear to have superior ability to find and enter their target and absorb cancer-destroying light. At thousands of times smaller than the width of a human hair, they are smaller than most other metal nanoparticles used in PAT and would appear to be safer because gold generally causes fewer negative reactions than other metals that come in contact with the human body, Zhang said.

"Previously developed nanostructures such as nanorods were like chopsticks on the nanoscale," Zhang said. "They can go through the cell membrane but only at certain angles. Our spheres allow a smoother, more efficient flow through the membranes."

Despite the initial success, Zhang said more extensive trails -- eventually involving humans -- are still needed to test the safety and efficacy of the technique before it goes mainstream.

More information

The U.S. National Cancer Institute has more about melanoma.

SOURCE: American Chemical Society, news release, March 22, 2009