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Gold
nanoparticles to 'cook' cancer cells Washington:
In a major advance in cancer treatment, nanotechnology researchers have developed
the first hollow gold nanospheres that search out and "cook" cancer cells. The
researchers say that the cancer-destroying nanospheres, smaller than the finest
flecks of dust, particularly show promise as a minimally invasive future treatment
for malignant melanoma, the most serious form of skin cancer. The hollow gold
nanospheres are equipped with a special "peptide" that draws them directly to
melanoma cells, while avoiding healthy skin cells. The nanospheres heat up when,
after gathering inside the tumour, they are exposed to near-infrared light, which
penetrates deeply through the surface of the skin. The researchers said that in
recent studies in mice, the hollow gold nanospheres did eight times more damage
to skin tumours than the same nanospheres without the targeting peptides, "This
technique is very promising and exciting. 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," explained study co-author Dr. Jin Zhang, a professor of
chemistry and biochemistry at the University of California in Santa Cruz. The
technique is actually a variation of photothermal ablation, also known as photoablation
therapy (PAT), a technique in which doctors use light to burn tumors. To develop
more effective cancer-burning materials, the researchers focused on hollow gold
nanospheres - each about 1/50,000th the width of a single human hair. In 2006
Zhang announced 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. "Previously developed nanostructures
such as nanorods were like chopsticks on the nanoscale. They can go through the
cell membrane, but only at certain angles. Our spheres allow a smoother, more
efficient flow through the membranes," said Zhang. Apart from being smaller than
other nanoparticles previously designed for photoablation therapy, gold is also
safer and has fewer side effects in the body than other metal nanoparticles. The
researchers equipped the nanospheres with a peptide to a protein receptor that
is abundant in melanoma cells, giving the nanospheres the ability to target and
destroy skin cancer. In tests using mice, the resulting nanospheres were found
to be significantly more effective than solid gold nanoparticles due to much stronger
near infrared-light absorption of the hollow nanospheres, the researchers say.
Now, Zhang is planning to try the nanospheres in humans, which requires extensive
pre-clinical toxicity studies. The findings of the study were presented at the
American Chemical Society's 237th National Meeting. -Mar
23, 2009 |