For the better part of a century, antibiotics have been instrumental in our treatment of infections, but unfortunately their time may be coming to an end. To avoid a future where once-routine procedures become life-threatening again, new ways to fight bacteria need to be developed. A new study has now shown oxygen can be weaponized against antibiotic-resistant bacteria, by way of nanoparticles activated by light.

Thanks to heavy use of antibiotics over several decades, bacteria have evolved resistance to many drugs, and are rendering new ones ineffective all the time. If the problem is left unchecked, reports suggest we may be headed for a grim future where these "superbugs" are responsible for up to 10 million deaths a year, and disturbingly, the European CDC warns that our last resort antibiotics are already beginning to fail in large numbers.

New antibiotics are in development, but they too will inevitably end up becoming useless as bacteria continue to evolve. Instead of taking part in a fruitless arms race, some scientists have turned to technologies that the bugs will never be able to develop resistance to, such as new material surfaces and lighting.

The new study, from researchers at the University of Cincinnati, also uses light. But rather than using UV light to destroy the DNA of the bugs, the team harnesses blue and red light to activate nanoparticles, known as photosensitizers, which react to the light by producing a toxic form of oxygen.

"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," says Peng Zhang, lead researcher on the study. "Then, the photosensitizers convert oxygen into reactive oxygen species that attack the bacteria."

This principle has been developed in the past, but there are a couple of major problems. For one, the particles tend to spread out too far to be able to coordinate their attacks, and being hydrophobic, it's difficult to disperse them into liquids where their targets usually live.

To overcome these problems, the researchers developed hybrid particles, combining the photosensitizers with noble metal nanoparticles. The team says the metals keep the photosensitizers together, allowing them to deal a bigger blow to a more localized area. In addition, the metal helps to produce more of the reactive oxygen species.

In testing the new technique, the team found that they were able to kill a variety of bacteria more effectively than treatments that didn't contain the metal nanoparticles. When tested on lab samples of human skin cells, the researchers found that they were unharmed, which bodes well for eventual human trials.

For the first application of the technology, the team has been awarded a patent for a spray or gel containing the nanoparticles. This would be applied to medical surfaces and instruments, sterilizing them by shining blue or red light onto them. Other potential uses might include applying the stuff directly to wounds to prevent infection, killing nail bed fungus or even skin cancer.

The research was presented at the National Meeting & Exposition of the American Chemical Society over the weekend.

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