Dr. Jörg Schwartz, firstname.lastname@example.org
EL PASO, Texas – When it comes to solar cells, “the larger,
the better” may be one of the first thoughts because more surface area helps
the cells convert more sunlight into electrical energy. The opposite is true at
the University of Texas, however, where a team of researchers is trying to make
photovoltaic devices smaller and smaller – with a different goal, of course.
The investigators are looking at improving cancer therapy, where
one of today’s most common approaches is injecting chemotherapeutic drugs
through an intravenous drip into the bloodstream. The drugs, usually targeting all
cells that divide quickly, come in contact with many organs as they travel through
the body on the way to their target. But along the way, they also attack noncancerous
cells that happen to divide rapidly. Most of the side effects are well-known, including
hair loss, reduced production of blood cells and inflammation of the lining of the
If doctors could deliver the drugs only where needed – targeting
them specifically to tumor tissue – many unwanted side effects could be avoided.
And this is where the solar cells come into play. The idea is that a small current,
produced by targeted illumination of a microscopic photovoltaic (PV) device, could
be used to detach a drug molecule that would otherwise be tied to the photoactive
During experiments performed on an in vitro model system, positively
or negatively charged “model” drugs were applied to opposite sides of
the miniature solar cell as a coating. Upon introduction of a light beam, one side
of the device became positively charged, repelling the positive-charged molecules
placed there by the researchers; the same thing happened with the negatively charged
side and negative model molecules.
This is a microscopic image of a solar device on the scale of a few micrometers. The
device can be coated with drugs that will be released upon exposure with IR radiation
inside the body. Courtesy of Drs. Gregory Nielson and Jose Luis Cruz-Campa, Sandia
The good news for applying this to a real organism is that near-IR
or laser light can penetrate tissues more than several centimeters deep. But there
are still challenges ahead. The first is making an extremely small solar cell.
“For this application, the PV device should ideally be a
few micrometers or submicrometers large,” said Dr. Tao Xu, assistant professor
and leader of the research. Also on his wish list toward clinical applications are
organic solar devices based on biocompatible or even biode-gradable materials.
“We believe we just opened the door of the brand-new applications
of the PV or solar cells to medicine,” Xu said, adding that researchers from
interdisciplinary fields are realizing more and more the value of this new technology.
He predicts that solar cells will be designed specifically for medical applications
After presenting their initial work at the AVS 57th International
Symposium & Exhibition 2010 in Albuquerque, N.M., in October, the investigators
now will work toward an animal tumor model with prostate cancer and will intravenously
inject microsolar devices loaded with anti-tumor drugs.
“We will see if these devices can travel to the tumor sides
and if the drugs can be effectively released from the devices and delivered into
tumor tissues upon exposure of the infrared laser light,” Xu said. “We
will also evaluate the therapeutic effects of this new delivery system.”