Gold Nanoparticles Show Promise for Killing Cancer Cells

Researchers have developed the first hollow gold nanospheres that search out and “cook” cancer cells. The cancer-destroying nanospheres show particular promise as a minimally invasive future treatment for malignant melanoma, the most serious form of skin cancer, the researchers said. Melanoma now causes more than 8,000 deaths annually in the United States alone and is on the increase globally.

The topic of a report presented at the American Chemical Society’s 237th National Meeting, the hollow gold nanospheres are equipped with a special “peptide.” That protein fragment draws the nanospheres directly to melanoma cells, while avoiding healthy skin cells. After collecting inside the cancer, the nanospheres heat up when exposed to near-infrared light, which penetrates deeply through the surface of the skin. In recent studies in mice, the hollow gold nanospheres did eight times more damage to skin tumors than the same nanospheres without the targeting peptides, the researchers say.

“This technique is very promising and exciting,” explained study co-author Jin Zhang, Ph.D., a professor of chemistry and biochemistry at the University of California in Santa Cruz. “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.”

This form of cancer therapy is actually a variation of photothermal ablation, also known as photoablation therapy (PAT), a technique in which doctors use light to burn tumors. Since the technique can destroy healthy skin cells, doctors must carefully control the duration and intensity of treatment.

Researchers now know that PATs can be greatly enhanced by applying a light absorbing material, such as metal nanoparticles, to the tumor. Although researchers have developed various types of metal nanoparticles to help improve this technique, many materials show poor penetration into cancer cells and limited heat carrying-capacities. These particles include solid gold nanoparticles and nanorods that lack the desired combination of spherical shape and strong near-infrared light absorption for effective PAT, scientists said.

To develop more effective cancer-burning materials, Zhang and colleagues focused on hollow gold nanospheres--each about 1/50,000th the width of a single human hair. Previous studies by others suggest that gold “nanoshells” have the potential for strong near-infrared light absorption. However, scientists have been largely unable to produce them successfully in the lab, Zhang noted.

After years of research toward this goal, Zhang announced in 2006 that he had finally developed a nanoshell or hollow nanosphere with the “right stuff” for cancer therapy: Gold spheres with an optimal light absorption capacity in the near-infrared region, small size, and spherical shape, perfect for penetrating cancer cells and burning them up.

The shells are also much smaller than other nanoparticles previously designed for photoablation therapy, he said. Another advantages is that gold is also safer and has fewer side effects in the body than other metal nanoparticles, Zhang noted.

The next step is to try the nanospheres in humans, Zhang said. This requires extensive preclinical toxicity studies.

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OH&S Digital Edition

  • OHS Magazine Digital Edition - October 2020

    October 2020

    Featuring:

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