Nanoparticles + light = dead tumor cells

Jul 29, 2008

Medical physicists at the University of Virginia have created a novel way to kill tumor cells using nanoparticles and light. The technique, devised by Wensha Yang, an instructor in radiation oncology at the University of Virginia, and colleagues Ke Sheng, Paul W. Read, James M. Larner, and Brian P. Helmke, employs quantum dots. Quantum dots are semiconductor nanostructures, 25 billionths of a meter in diameter, which can confine electrons in three dimensions and emit light when exposed to ultraviolet radiation.

Yang and his colleagues realized that quantum dots also give off light when exposed to megavoltage x-rays, such as those used in cancer radiotherapy. That property, the scientists realized, makes quantum dots an ideal mediator in therapies employing light-activated compounds to treat cancer.

A compound called Photofrin is the only photosensitizer currently approved by the FDA. Photofrin is absorbed by cancer cells and, upon exposure to light, becomes active and kills cells. It is currently used to treat certain kinds of shallowly located tumors, but Yang and his colleagues realized that combing Photofrin with quantum dots could create an efficient method to kill even deeply seated cancer cells.

Upon exposure to high doses of radiation, the dots become luminescent and emit light; that light triggers the cancer-killing activity of the Photofrin. In theory, the process, which so far has been studied only in cancer cells grown in culture, could work on tumors located too deep within the body to be reached by an external light source.

To prevent normal tissues from being affected by the treatment, the toxicity of the quantum dot-Photofrin conjugate is only activated when radiation is applied. Also, the area to be treated is targeted with conformal radiation, which is delivered with high precision within the three-dimensional contours of the tumor, with minimal spillover to surrounding healthy tissues.

As a result, Yang says, "the toxicity of the drug is substantially lower in the lower radiation dose area" outside the boundaries of the tumor. In tests on human lung carcinoma cells, the process resulted in a 2-6 times lower tumor cell survival compared to radiation alone, but with minimal toxicity to nearby cells.

Yang will describe the technique in his talk, "Enhanced Energy Transfer From Mega-Voltage Radiation to the Tumor Cell Killing Singlet Oxygen by Semiconductive Nanoparticles," on Tuesday, July 29, during the 50th annual meeting of the American Association of Physicists in Medicine (AAPM), the largest medical physics association in the world. The meeting takes place from July 27 to July 31, in Houston, Texas.

Source: American Institute of Physics

Explore further: Nanocontainers for nanocargo: Delivering genes and proteins for cellular imaging, genetic medicine and cancer therapy

add to favorites email to friend print save as pdf

Related Stories

For electronics beyond silicon, a new contender emerges

Sep 16, 2014

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Black hole thermodynamics

Sep 10, 2014

In the 1800s scientists studying things like heat and the behavior of low density gases developed a theory known as thermodynamics. As the name suggests, this theory describes the dynamic behavior of heat ...

Alcohol clouds in space

Sep 09, 2014

Yes, there is a giant cloud of alcohol in outer space. It's in a region known as W3(OH), only about 6500 light years away. Unfortunately it is methyl alcohol (commonly known as wood alcohol, though this stuff ...

Tiny graphene drum could form future quantum memory

Aug 28, 2014

Scientists from TU Delft's Kavli Institute of Nanoscience have demonstrated that they can detect extremely small changes in position and forces on very small drums of graphene. Graphene drums have great potential ...

Recommended for you

A nanosized hydrogen generator

18 hours ago

(Phys.org) —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

AdseculaScientiae
5 / 5 (1) Jul 29, 2008
Great breakthroughs and possible cures for cancer these last years, how much longer before we can say cancer is in the same category as other welltreatable diseases..?
gmurphy
not rated yet Jul 30, 2008
curing people with light, I love it!
E_L_Earnhardt
not rated yet Jul 30, 2008
Good work! Now if you can shield the surrounding cells from the X-ray burst you might prevent them from becoming the next cancer!