UC lights way with new skin care

Chemist Peng Zhang uses nanoparticles and a simple light-emitting diode like the kind found in flashlights to generate a chemical reaction that can kill harmful bacteria or even cancer cells. The treatment is so noninvasive, he hopes it can be sold over the counter for use at home.

“When you shine a light onto the nanoparticles, they generate something called reactive oxygen species that attacks the target. It could be bacteria or cancer cells,” Zhang said.

Zhang, an associate professor of chemistry in UC’s McMicken College of Arts and Sciences, has co-authored a half-dozen papers on the topic. He presented his latest research to the American Chemical Society national conference in August.

In his lab, Zhang prepares his patented nanoparticle photosensitizer that contains a silver core, a silica shell and a substance called hematoporphyrin. To activate the nanoparticles, he uses a commercially available LED that is brighter than most store-bought flashlights. Zhang prefers a blue bulb because it doesn’t generate as much heat as white ones.

The use of reactive oxygen has many potential applications but the most obvious, Zhang said, is to treat acne. Acne is one of the most common skin maladies, affecting more than 80 percent of teenagers. An estimated 50 million Americans have acne and a third of cases are so severe they require medical treatment.

Doctors say antibiotic resistance will be one of the biggest risks to human health in coming years, complicating everything from major organ transplants to outpatient surgeries. In his address to the United Nations in September, U.S. Department of Health and Human Services Secretary Alex Azar called antibiotic resistance a global threat that will need a global response.

“The more people are exposed to antibiotics, the more likely the bacteria inside their body can find ways to evade those antibiotics,” said Dr. Carl Fichtenbaum, an infectious disease expert in the UC College of Medicine and associate chairman of Medicine for Translational Research.

“I think if we could use a nonantibiotic approach to cure skin infections, that would be very helpful to limit the need for antibiotics and decrease the spread of resistance,” Fichtenbaum said. “So, I would be very interested in seeing if novel approaches like the photosensitizer using nanotechnology would offer an alternative to using antibiotics.”

Likewise, this method could help doctors treat early-stage skin cancer. Zhang said his photosensitizer could be useful in photodynamic therapy to destroy cancer cells such as carcinomas.

“At this point, we’re limited to topical treatments because you want the site to be easily accessible to light,” he said. “If the cancer is inside tissue, it’s quite a challenge to reach. I saw where they were using fiber optics to shine light onto tissue, but it’s not easy.”

But applications could include antifungal treatments to fight athlete’s foot, another persistent skin condition that is difficult to treat.

“It’s another condition that is very prevalent and uncomfortable,” Zhang said. “It’s a little more difficult to treat than bacterial infections. Fungus has a rigid membrane, unlike bacteria.”

Zhang said he envisions these treatments complementing rather than replacing existing cures.

“We’re trying to conserve critical antibiotics so you can save that silver bullet for when you need it,” Zhang said. “For minor conditions, you really don’t need to use antibiotics.”

Featured image above: UC chemistry professor Peng Zhang poses in front of a blue LED he is using to activate nanoparticles that can kill bacteria. Photo/Joseph Fuqua II/UC Creative Services.