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Markers could help lasers find skin cancer

U. MISSOURI (US) — Attaching “enhancers” to cancer cells could help photoacoustic scans, which use lasers to detect early signs of melanoma, identify other types of cancer.

“Eventually, a photoacoustic scan could become a routine part of a medical exam,” says Luis Polo-Parada, assistant professor of pharmacology and physiology at the University of Missouri. “The technique doesn’t use X-rays like current methods of looking for cancer. It could also allow for much earlier detection of cancer.

“Now, a cancerous growth is undetectable until it reaches approximately one cubic centimeter in size. Photoacoustics could potentially find cancerous growths of only a few cells. Unfortunately, our research shows that, besides some cases of melanoma, the diagnostic use of photoacoustics still has major limitations. To overcome this problem, the use of photoacoustic enhancers like gold, carbon nanotubes, or dyed nanoparticles is needed.”

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Photoacoustics uses pulses of laser light to heat cells for a fraction of a second. When the cells become hot they emit a tiny sound. Extremely sensitive microphones can hear those sounds. The strength of the sound depends on how much laser light is absorbed.

Since darker objects absorb more light they also emit more sound and can be found using photoacoustics.

“Some melanoma can be found by photoacoustics because the cells contain large quantities of melanin, a dark pigment,” Polo-Parada says. “Other cancers don’t have that much pigmentation; hence, they don’t stand out as much in photoacoustic scans. This is where enhancers may be able to help by labeling cancer cells and making them stand out in a scan.”

Polo-Parada in collaboration with Gerardo Gutierrez-Juarez, a researcher from the University of Guanajuato, Mexico, found that out of seven types of cancer cells, only one type of melanoma was dark enough to produce a sound strong enough to be distinguishable from the rest. Their findings are published in the journal AIP Advances.

The photoacoustic technique holds promise in the fight against cancer, notes Polo-Parada, but it is too soon to say exactly when the public will benefit. Eventually, other diseases that cause changes in the coloration of cellular tissue, such as malaria, could be found by photoacoustics.

Source: University of Missouri

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