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Research: Activated oxygen helps against antibiotic-resistant bacteria


Experts are developing new forms of treatment for MRSA

Antibiotic-resistant bacteria are becoming an ever greater threat to humanity. The life-threatening bacterium MRSA is no exception. It can spread quickly and is resistant to previous treatment. Researchers are now developing a technique that uses light to activate oxygen so that it is able to fight antibiotic-resistant bacteria.

In their current study, the University of Cincinnati scientists found that light-activated oxygen can be used to treat antibiotic-resistant bacteria. The doctors published the results of their study at this year's 256th National Meeting & Exposition of the American Chemical Society (ACS).

New forms of treatment could also help with cancer

The newly developed method could help fight resistant MRSA bacteria without resorting to antibiotics. The method could also be used to treat other microbial infections and possibly even cancer, experts say.

Disinfection in hospitals needs to be improved

Clinical facilities currently have little alternative when trying to cure MRSA (methicillin-resistant Staphylococcus aureus). One of these methods is improved disinfection. For example, a recent study found that disinfecting all patients admitted to an acute ward halves the rate of infection in the bloodstream. However, this procedure cannot be carried out in most hospitals, the doctors explain.

Dye molecules for the treatment of MRSA?

Instead of relying on antibiotics, which are no longer effective against some bacteria such as MRSA, the scientists used photosensitizers in their study, mostly dye molecules that are stimulated when illuminated with light, says study author Dr. Peng Zhang from the University of Cincinnati in a press release. Then the photosensitizers convert oxygen into so-called reactive oxygen species (oxygen radicals), which then attack the bacteria, the expert adds.

Why the use of photosensitizers is problematic

Although other research teams have experimented with the use of these types of photocatalysts to kill bacteria, they have not destroyed enough microorganisms to effectively prevent infections. Molecular photosensitizers tend to be insufficiently correlated to cause significant damage. In addition, many of them are hydrophobic. This makes it difficult to disperse them in aqueous media, where microorganisms typically exist, the researchers say.

New photosensitizer contains precious metal nanoparticles

The scientists developed a new, water-dispersible, hybrid photosensitizer that contains noble metal nanoparticles that are coated with amphiphilic polymers to encapsulate the molecular photosensitizers. These hybrid photosensitizers are much more effective in killing a large number of bacteria than corresponding compositions that do not contain metal particles, the experts explain.

According to the researchers, these new nanoparticles offer two advantages. The metal has a so-called plasmonic enhancement effect, which promotes the generation of a reactive oxygen species, while at the same time concentrating the photosensitizers in one place in order to achieve a more localized attack on the bacterial cells. A focused attack is always more effective, compared to many individual attacks, doctors add.

How would a treatment work?

Photosensitizers can be made into a spray or gel. If the spray were to be released to the market at some point in the future, it could be sprayed onto any surface by medical professionals and then illuminated with blue or red light to remove any bacteria, including MRSA. This method could also be promising in direct wound applications to remove infections and aid healing.

Initial trials on human skin were promising

Scientists recently performed experiments on human skin laboratory samples and found that the photosensitizer did not kill the skin cells. In addition to eliminating MRSA, the nanoparticles are also ideally suited to destroy skin cancer cells. The nanoparticles work effectively with the illumination of red light, which has a long wavelength that penetrates deep into the skin. This is particularly important for the treatment of skin cancer. The study also found that the nanoparticles also eliminate nail fungus. (as)

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