Treating Cancer With Light

Photovoltaics are often touted as potential game-changers as a source of alternative energy, but new microscopic versions of solar cells could soon be lifesavers for millions of cancer patients.

Scientists are developing new solar cell-powered cancer therapies that could -- if approved for clinical use -- make treatment faster, less painful and more effective.

"I looked at one report from Sandia National Labs about how they could fabricate their really small solar cells," said Tao Xu, a scientist at the University of Texas at El Paso, who recently presented his research at the AVS conference, "and I figured we could probably use this new device for biomedical research -- in particular to develop a target that could deliver cancer therapies."

The new solar cells are similar to the black silicon panels that cover rooftops and harvest electricity from sunlight, yet are far smaller -- tiny enough that the human eye cannot see them unaided.

The new microscopic solar cells absorb certain colors of light, like red, that can penetrate the skin and several inches of flesh. That light energy is then converted into electrical energy.

The electricity allows the scientists to impart a charge, either negative or positive. The microscopic solar cells would be coated with a drug that also has a charge, either positive or negative. If both the solar cell and the drug end up with the same charge, the drug is pushed away from the solar cell and into the tumor, where it does its job.

Unlike other proposed targeted therapies using nanoparticles, which are coated with antibodies that recognize and stick to tumors, the new solar cells would be dispersed through the entire body. A few of them would eventually find their way to the tumor.

The solar cells will only release the drug when activated by light. Solar cells that are not hit by the light never release their toxic cargo, and should eventually be filtered out by the kidneys.

Using charged particles in conjunction with charged drugs is just one way scientists hope to destroy cancer with light.

Karen Brewer, a scientist at Virginia Tech, is also exploring light-activated cancer therapies. She says that light-activated cancer treatment, if approved for human use, would have many benefits over existing cancer treatments.

"The current methods we have for treating cancer rely on administering the active form of a drug to the entire patients, and relying on a relatively small portion of the drug to kill the cancer cells," said Brewer. "But the end result is that people get very sick and you end up damaging other (healthy) cells."

New light-activated therapies would target only the harmful cancer cells, limiting the damage to healthy cells, and making treatment faster, less painful and more effective than today's therapies.

The new therapies hold great promise, said Brewer. However, it will take years before these therapies are used clinically.