Study: Light-activated oxygen kills infections, disease

Aug. 20 (UPI) -- Researchers have developed a way to treat antibiotic-resistant staph infections by activating oxygen with light.

This method also potentially can treat other microbial infections and possibly cancer, according to scientists at the University of Cincinnati. They presented their findings Sunday at the 56th National Meeting & Exposition of the American Chemical Society in Boston.

There are few ways to treat patients with methicillin-resistant Staphylococcus aureus, or MRSA. Some hospitals have resorted to disinfecting every patient admitted to an acute-care setting.

"Instead of resorting to antibiotics, which no longer work against some bacteria like MRSA, we use photosensitizers, mostly dye molecules, that become excited when illuminated with light," Dr. Peng Zhang, a researcher at Cincinnati, said in an ACS press release. "Then, the photosensitizers convert oxygen into reactive oxygen species that attack the bacteria."

Other teams have tried types of photocatalysts to kill bacteria, but they don't destroy enough microorganisms to rid infections.

In a molecular form, these photosensitizers can't be corralled enough to do significant damage and many are hydrophobic, meaning they repel or fail to mix with water.

Instead the researchers designed new, water-dispersible, hybrid photosensitizer. It includes noble metal nanoparticles with amphiphilic polymers to entrap the molecular photosensitizers.

This process was much more effective at killing a variety of bacteria than other formulations .

They said their process promotes the generation of more reactive oxygen species and concentrated the photosensitizers in one place for a more localized hit on bacterial cells.

"If you want to attack a castle, and you just let all these people attack individually, it is not very effective," Zhang said. "Instead, if you have the same number of people grouped together attacking the castle at one point, it is possible to cause more damage."

Zhang's patent for hybrid photosensitizers can be formulated into a spray or gel. Medical professionals could put it on any surface and then illuminate it with blue or red light to clean away the bacteria, including MRSA, he said.

Notably, it can be used in wound applications to eliminate infection and assist in healing after tests found that the photosensitizer didn't kill skin cells.

Zhang also said the nanoparticles are ideal for destroying skin cancer cells. They work effectively with the illumination of red light as a long wavelength that penetrates deep below the skin.

And the nanoparticles have been shown to eliminate nail bed fungus, the researchers said.