Trends in Nanotechnology: Killing Cancer with Light

by Steve O'Keefe on October 5, 2010

Laser light

On page 133 of MINITRENDS, Dr. John Vanston describes an interesting experiment in killing cancer cells with light therapy:

A very interesting application of nanotechnology in the medical field is a treatment for cancer currently being developed commercially by BioSpectra. This treatment is based on research developed by Rice University and the M.D. Anderson Cancer Research Institute. When reduced to nano-size, the color of gold depends on the size of the particles, e.g., red, blue or green. In this treatment process, gold particles of a size that corresponds to visible light are attached to biological molecules that migrate to the location of the cancer. The patient is then subjected to a beam of light of the matching color. The energy of the light is deposited in the gold particles, raising the temperature, and burning up the cancerous cells. Visible light can penetrate about 15 centimeters (roughly, six inches) into the body without damaging non-cancerous tissue, contrary to current radiation treatments.

Light therapy has a growing number of uses in the medical field. While the increasing use of light in medicine is a “megatrend,” the particular applications that are coming online in the next few years are Minitrends. These include not only using light to kill unwanted cells, but also to detect them.

Anne Trafton, a biologist and science journalist writing in MIT News, reports on the efforts of MIT researcher Geoffrey von Maltzahn and Harvard-MIT researcher Sangeeta Bhatia to use gold nanorods as a cancer detection tool. Trafton explains how the process works:

Gold nanoparticles can absorb different frequencies of light, depending on their shape. Rod-shaped particles, such as those used by von Maltzahn and Bhatia, absorb light at near-infrared frequency; this light heats the rods but passes harmlessly through human tissue.

The nanorods’ homing abilities also make them a promising tool for diagnosing tumors. After the particles are injected, they can be imaged using a technique known as Raman scattering. Any tissue that lights up, other than the liver or spleen, could harbor an invasive tumor.

Last week, Katia Moskvitch, a Canadian science writer working for the BBC, reported on advances in “Raman spectroscopy,” a method for using light in diagnostics. Raman spectroscopy can rapidly analyze the molecular composition of tissue and bone, detecting abnormalities. Moskovitch interviews University of Michigan researcher, Michael Morris, who says:

Raman gives you a molecular fingerprint, a composition of whatever it is you’re measuring. In diseased states, the chemical composition is either slightly abnormal or very markedly abnormal, depending upon the diseases.

The hope is to conduct diagnostics without needle sticks, blood drawing, or incisions. One of the most sought-after applications is a glucose meter for diabetics, with which the patients would only have to shine a light to their skin, rather than having to prick themselves to draw blood. Shirley S. Wang, a clinical psychologist from Yale University, wrote in The Wall Street Journal that researchers at the G.R. Harrison Spectroscopy Lab at MIT hope to have a wearable diabetes monitor within two to five years.

These are some of the many interesting uses of light in medicine that show promise for development in the near future.

STEVE O’KEEFE
News Editor, Minitrends Blog

Source: “Painless laser device could spot early signs of disease,” BBC News, 09/26/10
Source: “Targeting tumors using tiny gold particles,” MIT News, 05/04/09
Source: “Researchers Beaming at Light’s Medical Uses,” The Wall Street Journal, 08/31/10
Image by alanymchan, used under Creative Commons license.

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