Two UW professors are looking for a cure for cancer — with particles of gold.

Using relatively simple basic principles, Dr. Younan Xia of the chemistry department and Dr. Xingde Li of the bioengineering department are collaborating on a project that shows promise for the fight against cancer.

One of the principles behind this UW study dates back to the creation of those old stained glass windows seen in churches, some of which have red colors that “aren’t caused by pigments, but by gold particles in the glass,” Xia said.

Stained glass makers started using gold particles in glass because it would remain the same color, whereas organic pigments would often fade over time.

What the people of this time probably did not know was that gold can be tuned to make many different colors.

“When gold is in very small pieces, it is no longer golden … but rather ruby red … or blue … depending on the size,” Xia said. “All different colors are possible.”

Xia has a rainbow of liquids that he keeps in his office, each containing differently tuned gold particles. The bits in his rainbow vials are nanocages, or gold nanoparticles.

Xia explained that this principle works because “light is an electromagnetic field [and] metal has free electrons.” Like the specific reflecting patterns these particles have, there is also similar specificity for the absorption of light for these particles.

But what does the absorption of light have to do with cancer?

The specifically designed gold nanocages work by attaching to antibodies or ligands that can selectively target the cancer cells. The better these connections are, the more effective the process.

The cells are then exposed to light that the gold absorbs, causing it to heat up and thereby also heating up the cancer cell. Thus, when certain light is shined on the cages, they will heat up so much that they melt. When this happens while they are attached to a cell, the cell will be destroyed.

The main importance of this is that it provides selectivity for which cells will be targeted in the treatment — selectivity for what is and what is not killed.

The problem of exposing all of the tumor cells in one’s body to light is circumvented by tuning the nanocages to an infrared wavelength so that the light may penetrate the body’s healthy tissue.

The gold particles in this study are shaped as tiny nanocages, Xia said — hollow gold boxes with the corners cut off and tiny openings at the center of the facets.

Using gold to treat cancer may seem like an expensive endeavor, but that is not the case.

“Material-wise, it is pretty cheap,” Xia said. “The cage is 50 nanometeres with three or four nanometer thickness. The antibody would be more expensive than the cages. … The major cost would be in the development of the clinical trials.”

Both scientists say that before all of this happens, and before this goes into any sort of clinical trial, they must first do what they are doing now — exploring the properties, functions and potential applications of this technology.

“This is a very preliminary study,” Xia said. “It will take a long time to go to a clinical phase.”

This technology, the scientists estimate, will not be available for at least another five to 10 years.

They have just started animal model studies, Xia said.

There are still several things they need to know, such as the biodistribution, or where the materials in the body would go after they are used, Li said.

Among other things, Li said his lab is “exploring the potential biomedical applications of the nanocage … and the fundamental optical properties of the nanocage.”

The drug release is the one that is farthest off. It theoretically works by putting drugs inside the nanocages and then releasing these drugs in the appropriate places and amounts using different exposures to light.

Li said that the drug release application of the nanocages is far in the future, requiring more precise tuning of the optical properties of the nanocages and the intensity of the light.

The results look promising so far — Li’s lab has experimented with different intensities and lengths of light exposure, and there has been little to no damage of the untreated tissue.

The study into nanocages has been going on for five years.

“We’re very excited about it,” Li said. “This collaboration has been prosperous.”

Reach reporter Emma Mullen at features@thedaily.washington.edu.